April 2018–March 2019

Kavli IPMUANNUAL REPORT 2018

CONTENTS
FOREWORD

2

1 INTRODUCTION

4

2 NEWS & EVENTS

12

3 ORGANIZATION

14

4 STAFF

18

5 RESEARCH HIGHLIGHTS

24

5.1 A Mysterious Kac-Moody Factor ���������������������������������������������������������������������������������������������������������������������������������������������������� 24
5.2 Cosmology from Cosmic Shear Power Spectra Using Subaru Hyper-Suprime Cam Data���������������������������������� 26
5.3 Coulomb Branches of Quiver Gauge Theories with Symmetrizers �������������������������������������������������������������������������������� 27
5.4 Swampland Conditions ���������������������������������������������������������������������������������������������������������������������������������������������������������������������� 28
5.5 Mapping the High-Redshift Cosmic Web in 3D ���������������������������������������������������������������������������������������������������������������������� 29
5.6 Perverse Sheaves and Their Categorical Generalizations �������������������������������������������������������������������������������������������������� 30
5.7 Closing in on the Ultimate Dark Matter Limits Forecast by the Fermi Gamma-Ray Space Telescope ���������� 31
5.8 Gravitational Waves and Dark Matter ������������������������������������������������������������������������������������������������������������������������������������������ 33
5.9 A Machine-Learning Application to Cosmological Structure Formation �������������������������������������������������������������������� 34
5.10 Good Vibrations: Effective Field Theory Harmonics �������������������������������������������������������������������������������������������������������������� 35
5.11 A Big Step Forward for LiteBIRD to Prove the Inflationary Universe ������������������������������������������������������������������������������ 37
5.12 Medical Applications of Gamma-ray Imaging ������������������������������������������������������������������������������������������������������������������������ 39

40

7. CONFERENCES

42

8. CONFERENCE PRESENTATIONS AND SEMINAR TALKS43

9. OUTREACH AND PUBLIC RELATIONS

44

Kavli IPMU

Annual Report 2018

Copyright © 2019 Kavli IPMU
All rights reserved
Editors: Tomiyoshi Haruyama (Chair), Chiaki Hikage, Misao Sasaki, Yoshihide Sakai
Editing Staff: Shoko Ichikawa
Kavli Institute for the Physics and Mathematics of the Universe
UTIAS, The University of Tokyo
5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583, Japan
Tel: +81-4-7136-4940 Fax: +81-4-7136-4941
https://www.ipmu.jp/

6. AWARDS

April 2018–March 2019

April 2018–March 2019

Kavli IPMU

Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU)
The University of Tokyo Institutes for Advanced Study
The University of Tokyo
5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583, Japan

TEL: +81-4-7136-4940

ANNUAL REPORT 2018

FAX: +81-4-7136-4941 http://www.ipmu.jp/

ISSN 2187-7386

Printed in JapanOn the cover:
Photo at the all-hands meeting of Kavli IPMU members on October 15, 2018

Foreword

Foreword

Within a week after I became the director, I assembled a committee to start strategic planning for our next ten
years. The committee worked diligently, meeting every month, interviewing experts and leaders of various
research areas, discussing with our faculty members, and organizing conferences to learn new opportunities.
A tentative report was submitted in June, and was reviewed by our external advisory committee. The final
report was submitted to me in August. It will guide our priorities in hiring and allocating our resources in the
coming years.
During my inaugural address, I also affirmed my commitment to provide an inclusive and supportive environment to the diverse group of people at the institute. This year, we rolled out several new administrative procedures to improve diversity in our scientific staff, visitors, and participants of our conferences. We have alsoestablished our code of conduct, reviewed and revised our harassment training materials, and diversified ourleadership. We are also preparing bias training to improve our hiring practices. The weekly women’s lunch,initiated by Professor Yukari Ito this year, provides network opportunities for female members of our community.
Over the past year, we have had several exciting developments in our research. The Hyper Suprime-Cam teamat the Subaru Telescope produced their first set of 40 scientific papers. Among them was a three-dimensional
dark matter map with unprecedented width and depth, determination of the lumpiness of matter in theuniverse, and constraints on primordial black holes. Our Belle II team successfully delivered silicon vertex
detectors to the collider facility at KEK. Their B-physics experiment is in full operation, and they are busily
analyzing data. In Kamioka, following the successful completion of our R&D effort at Evaluating Gadolinium’s
Action on Detector Systems (EGADS), Super-Kamiokande is being prepared for gadolinium loading. This will
make neutrons visible, allow positive identification of anti-neutrino interactions, and greatly reduce physics
backgrounds. We are expecting the first detection of diffuse supernova neutrinos from the universe before
2022.

Hirosi Ooguri
DirectorI

am delighted to present our 2018 annual report to you.
I became the second director of this institute a year ago, on 15 October 2018. Hitoshi Murayama, my predecessor, did an excellent job in creating the institute and bringing it up to the forefront of basic science
research. My mission is to turn this successful start-up into a sustainable organization, keeping and exceeding
our high level of research activities.

We also heard two exciting announcements about our future projects. ISAS, the science branch of JAXA, hasapproved the launch of the LiteBIRD satellite in eight years from now to perform an all-sky CMB polarization
survey and to test cosmic inflation, in particular its single-ﬁeld large-variation slow-role models. MEXT
announced that they are requesting 1.8 billion yen in the fiscal year 2020 budget to begin construction ofHyper-Kamiokande in Kamioka. It will accumulate neutrino statistics twenty times faster than the current T2K
and will help us determine neutrino parameters. It will also look for proton decay to test a variety of grandunification models.
I hope you will enjoy reading this report on our research.

In my inaugural address last fall, I laid out a couple of initiatives that I wanted to implement immediately.
One was to conduct long strategic planning exercises. The institute was established in 2007, and we have hadmany scientific achievements since then. Some of the projects we started twelve years ago have run theircourse, and new opportunities are emerging. As we move into a sustainable mode of operation, we shouldcarefully choose our research directions, identifying the most effective way to use our resources, taking calculated risks, and aim to become the best at what we do. The choices we make should be guided by the institutemission, which is to solve the most fundamental questions about the Universe.

2

Kavli IPMU Annual Report 2018

Kavli IPMU Annual Report 20183

1

IntroductionH

irosi Ooguri, Fred Kavli Chair in Theoretical
Physics and Mathematics and the Founding
Director of the Walter Burke Institute for Theoretical Physics at the California Institute of Technology(Caltech), became the new Director of Kavli IPMU on
Oct 15, 2018. H. Ooguri is a world-renowned scientist
both in physics and mathematics, and is a recipient of
the inaugural Leonard Eisenbud Prize for Mathematics
and Physics, awarded by the American MathematicalSociety. He has extensive leadership experiences as theFounding Director of the Walter Burke Institute for
Theoretical Physics at Caltech and the President of the
Aspen Center for Physics. He initiated a long-term strategic planning exercise for the next 10 years, building
on our achievements and current scientific activities. H.
Ooguri received the 2018 Hamburg Prize for Theoretical Physics. This was the first year the prize covers allareas of theoretical physics. His paper on de Sitterswampland conjecture had a major impact on cosmology and became the most cited paper in high energy
theory in 2018.
FY2018 is the second year from the 5-year extension
period of the WPI funding. We have proposed the following 9 challenges for the extension period addressing new objectives. Below are brief summaries of oureffort to meet each challenge.

1. Creating new areas and tools of statistics, integrating
mathematics with observation and experiments
The JST CREST project “Statistical Computational Cosmology” led by N. Yoshida is aimed at developing fast
imaging data analysis applications for the Subaru HSC
survey. In 2018, they developed the “Dark Emulator”
that outputs statistical quantities and spatial clusteringof galaxies needed for cosmological parameter inference with weak gravitational lensing observation. The
emulator is based on modern statistical techniques,
such as Gaussian process and principle component
analysis, as well as a large simulation database. It has
already been used in several publications by the HSC

4

Kavli IPMU Annual Report 2018

Introduction

INTRODUCTION
collaboration. They have also developed a deep-learning method based on generative adversarial networks
to reduce the noise in gravitational lensing measurements.

categories, to a certain class of perverse schobers. The
latter are natural systems of derived categories analogous to perverse sheaves, introduced earlier by M.
Kapranov and V. Schechtman.

2. Creating new synergies among fields not imaginedat the launch
An agreement (2017-2020) has been made between
the Kavli IPMU and ISAS/JAXA to transfer hard X-ray
and gamma-ray imaging technology to nuclear medicine and to set up a new laboratory at the Kavli IPMU for
detector R&D. We also established an agreement
between the Kavli IPMU and National Cancer Centerand have started in-vivo imaging experiments of small
animals using a variety of radio-isotopes. For thisresearch, JSPS Kakenhi (Grant-in-Aid for Scientific
Research on Innovative Areas, PI. T. Takahashi) has been
granted.

4. Executing projects successfully to produce worldcompetitive results on dark energy, dark matter, andinflation• The Hyper Suprime-Cam team has measured how
cosmic structures including dark matter have
evolved as a function of cosmic time using gravitational lensing effects, and determined the parameterof clumpiness of the Universe today with the world’s
highest-level precision. The construction of the Prime
Focus Spectrograph instrument is well underway tostart science operation in 2022. All 2550 fiber positioners “Cobra”, as well as all science-grade detectors,
have been delivered to Hawaii and the team is now
carrying out various tests, including image quality
and thermal performance.
• XMASS-I detector has been completed, and thexenon has been safely recovered. Seven papers were
submitted and five published in 2018. Machinelearning has been used for event classification todiscriminate events from the detector’s inner surface
contaminating data sets. The Kavli IPMU is leading
the Japanese participation in the XENON1T detector's impending upgrade to XENONnT.
• T2K released new oscillation results at a KEK colloquium in January 2019. These results disfavor CP
conservation at the 95% confidence level. Oxford/
the Kavli IPMU graduate student T. Vladisavljevic has
completed his thesis work to update the T2K flux
calculation with replica target data collected by theNA61/SHINE experiment. With his work, the uncertainty on the T2K flux calculation has been reduced
from 10% to 5%.
• CMB experiments have been actively led by the Kavli
IPMU team. POLARBEAR2 reached to the first light inDecember 2018. Simons Observatory finished thedesign review and is now in fabrication phase. Lite-

3. Discovering new major framework for geometric
thinking in mathematics and physics with the derived
and non-commutative geometry, such as to unify various types of dualities
Our mathematicians have made substantial progressin using derived and non-commutative geometry as a
new major framework for geometric thinking in mathematics and physics. Y. Toda has developed new concepts of d-critical (i.e., derived critical) loci and flips. This
has allowed him to extend several fundamental resultsof birational geometry, such as wall-crossing equivalences, to a broad class of derived moduli spaces
important in physics. One of the tools to study wallcrossing has been the cohomological Hall algebra(COHA), but its precise definition was restricted toquiver-like situations. M. Kapranov, jointly with E. Vasserot, defined and studied COHA for algebraic surfaces,
based on ideas of derived geometry. F. Sala, with M.
Porta, gave a direct definition of the K-theoretical version using derived moduli spaces. The work of W. Donovan and T. Kuwagaki extended the homological mirror symmetry, originally an equivalence of derived

BIRD finished Pre-phaseA2 and is in process of downselection with its outcome in 2019.
• Belle II completed detector construction, where the
Kavli IPMU team successfully produced outermost
layer devices of SVD, and started data taking in March
2019.
5. Attracting and retaining the best and broadly minded scientists from around the world
We retained the best and open-minded scientists fromaround the world. T. Takahashi and H. Nakajima were
newly appointed as Principal Investigators (PIs), andtotal number of PIs has become 28 (7 non-Japanese:
25%, 11 on-site: 39%). T. Takahashi is a leading astroparticle physicist on developing hard X-ray and gamma
ray detectors in satellite and rocket experiments. He
started a new collaboration with JAXA/ISAS and Keio
University School of Medicine to apply these detectors
to biomedical research. H. Nakajima, who received theCole Prize in Algebra in 2003, is a distinguished mathematician and conducts research as a leader in a mathematical study of gauge theories, which have their origin in mathematical physics. Former Director H.
Murayama became a University Professor of the University of Tokyo and the Hamamatsu Professor of the
Kavli IPMU. K. Martens has been appointed the first
Director of the Kamioka-branch. This demonstrates thefact that the Kavli IPMU has established a truly international environment and support system, where a foreign researcher whose first language is not Japanese
can take such a leadership role.
Our faculty members play leading roles in each field
and include PIs of big international projects such as
Belle II, T2K, KamLAND-Zen, HSC/PFS, EGADS, and LiteBIRD.

Kavli IPMU Annual Report 20185

Introduction

Introduction

6. Bringing successful system reforms to the rest of the
University and other research institutions to help boost
the overall competitiveness of Japan on a global scale
Kavli IPMU administrative staff members were awarded
the UTokyo’s 2018 Special Prize for Business Transformation from the President for the sixth time, following
2008, 2013, 2015, 2016 and 2017. The Kavli IPMU teamdeveloped and is running a smartphone app, which
provides step-by-step information in English about
how to take public transport from the international
airport, how to find and ride the free shuttle bus to
Kashiwa campus from the train station, and maps thatshow where individual researcher offices are. This has
triggered administrative staff in other departments tostart developing their own smartphone apps, further
advancing system reforms.
The 2008 achievement for “web site to accept the foreign researchers in Kashiwa Campus” has already beenrequested to be adopted by administrative sections ofmany other faculties. The 2013 “thoroughgoing safety
education by network distribution of education video
and final quiz” has been requested to be adopted by
the UTokyo environmental and safety research centerin Kashiwa, Graduate school of Engineering UTokyo,
Graduate school of Mathematical Science UTokyo and
ICRR. The 2015 “language website to explain UTokyo’s
employee procedures for international researchers”has
been used freely through the UTokyo website. The
2016 “Win-Win project towards University Globalization” has been requested by the UTokyo hospital medical administrative section and ICRR. The 2017 “E-learning for Sexual Harassment Prevention” video in English
has been adopted as the official education course of
the University Harassment Counseling Center.
7. Making a serious attempt to create a new international graduate program with vigorous student
exchanges
Several doctoral students in astrophysics or particle
physics at U. Oxford are being supervised by faculty

6

Kavli IPMU Annual Report 2018

members of the Kavli IPMU, and are being provided theopportunity to conduct research in collaboration with
Kavli IPMU researchers. The Kavli IPMU is also working
with another international graduate program in physics (GSGC), which we hope will be extended to astronomy. Young students are becoming attracted to the
Kavli IPMU. A group of UTokyo and Kavli IPMU faculty
members, including Y. Kawahigashi (representative), T.
Kohno, A. Bondal, M. Kapranov, I. Ueda, and Y. Yamazaki,
are planning to submit a proposal for a student
exchange program between Hamburg University,
entitled “Higher algebraic structures and their concrete”, to the JSPS and German Research Foundation(DFG). The proposal includes exchange of several
graduate students per year, aiming to start in FY 2021.
Five members visited the Hamburg University to discuss the proposal, and a proposal from the Germanside was submitted in February 2019.
8. Enlarging the force for outreach to young students,
by organizing workshops for scientists and highschool teachers
In FY 2018, the Kavli IPMU kept collaborating with
CoREF (Consortium for Renovating Education of the
Future) to find a way to place the latest advances inscientific research into the high school curriculum. An
event was carried out to test the development of aninteractive lesson called “From high school physics tofrontier research of the Universe”, which Kavli IPMU PI H.
Murayama spoke and took part in. On July 29, 2018,high school students and teachers were invited to try
learning about the universe.
In Japan, the number of women who choose careers inscience, particular physics, is still extremely low. Students with an interest in physics are faced with many
challenges, including a lack of female leaders who cangive them advice, and few peers to share their issues. To
help resolve this problem, since 2016 the Kavli IPMU
has co-hosted a science career event together with the
UTokyo’s Institute for Solid State Physics, and the Insti-

tute for Cosmic Ray Research, specifically aimed at
female undergraduate and graduate students. At theevent, a number of speakers talk about their own career
paths, and discussion times are extended to encourage
participants meet other participants to build up theirown support network. Lately, an after-event dinner has
been introduced for students wishing to have moretime get to know other participants. Co-hosting theevent has allowed the hosts to cover a wide range of
research fields including particle physics, nuclear physics, astronomy, solid state physics, and engineering. In
the past, participants have commented that listening
to working women with science careers talk about
their own career choices has been a great help in thinking about their own future choices.
H. Murayama appeared on NHK documentary series
Last Lecture as“Physicist Hitoshi Murayama”. Recording
took place in a lecture hall at the UTokyo’s Hongo campus. More than 100 university undergraduates andgraduate students came to hear Murayama’s lecture,
which was made for the program. His story about how
he became H. Murayama the researcher was wellreceived by viewers, and the episode became the fifth
most watched show on NHK’s online channel on 22
February. Because of its popularity, NHK-BS1 aired a rerun of the program on 23 February.
9. Attaining sufficient stability of the organization sothat we can bring our research objectives beyond the
WPI funding
The positioning of the Kavli IPMU within UTokyo isquite clear. President Gonokami’s ‘Vision 2020’ emphasizes the importance of “Expansion and Establishmentof Internationally-renowned Bases for Research”. An
action to realize this vision‘Action 2020’has been set up
to “establish and expand upon internationallyrenowned bases for research at UTokyo by carrying out
such initiatives as advancing the development of boththe University’s strongest fields in which it is leading theworld and unique areas of original research whichshould unwaveringly continue to be studied, promoting joint research and international collaboration that
goes beyond the framework of UTokyo, and creating
new, interdisciplinary knowledge that is the first of its
kind in the world.” As has already been declared by the
President at the WPI Program Committee meeting inrecent years, the President recognizes the Kavli IPMU
perfectly matches his vision as a role model for the restof the University. The Kavli IPMU enhances the value ofthe University, which enables the University to attract
new revenues. It is reasonable for UTokyo to support
the Kavli IPMU with top priority. We have made theeffort to strengthen the University’s financial base.
Based on this stance, UTokyo has put together a planfor the extension period and beyond. UTokyo has
already provided 10 tenured positions, and permanent
assignment of nine administrative staff members.
Thanks to MEXT, from FY 2018, the ‘university functionality boost’ budget from MEXT for 13 positions and for
operation has been approved to be a permanent budget. The University will maintain and hopefully expand
the Kavli IPMU even after WPI support finishes.
A new budget request in the period from FY 2019 to FY
2021 was ranked as No.1 in UTokyo, and a budget for
the first year has been secured. This budget request is
crucial to sustain the Kavli IPMU permanently, and wewill keep making the request for the following two
years.
In the following pages, various statistics are shown inplots: the lists of seminar & conferences, publications,and conference talks can be found in Kavli IPMU webpage, https://www.ipmu.jp/en/research-activities on“Research Activities”

Kavli IPMU Annual Report 20187

Introduction

Total Number of Staff
297

300

273

300

291

311

RESEARCH ACTIVITIES

318
2000

285

1,689

247

250

230

1,449

1500

202

200

549

158

165

100

80

50

194

209

236

245

255

259

252

274

642

279
1000

478
500

63

18
0
3
21

63
10
7
80

862

125

21
30
32
29
27
28
31
27
25
28
27
22
10
18
11
10
11
10
10
10
10
10
10
11
10
3
7
0
Oct. 2007 Mar. 2008 Mar. 2009 Mar. 2010 Mar. 2011 Mar. 2012 Mar. 2013 Mar. 2014 Mar. 2015 Mar. 2016 Mar. 2017 Mar. 2018 Mar. 2019
125
22
11
158

165
27
10
202

194
25
11
230

209
28
10
247

236
27
10
273

245
30
10
285

255
32
10
297

259
31
10
300

RESEARCHERS

252
29
10
291

274
27
10
311

279
28
11
318

Percentage of Overseas

300

250

44%
52%

200

56%
150

40%

41%

38%
98
79

105

35%

90

41%

0

168
65
103

372
103
269

432
345

103
269
372

345
87
432

50

41%

8

17
46
28%
2%

Kavli IPMU Annual Report 2018

60
65
48%
5%

92
73
56%
6%

111

336

478
384
862

392
238
630

495
336
831

642
807
1,449

549
1,140
1,689

249

246

711
490
1,201

569
413
982

510
428
938

184

192

632
629
1,261

200

131

147

150

169

150

163

186

143
50

79
130
38%
2%

629

136

102

94

100
94
52%
5%

428

250

28%
18
3
0
Oct. 2007 Mar. 2008 Mar. 2009 Mar. 2010 Mar. 2011 Mar. 2012 Mar. 2013 Mar. 2014 Mar. 2015 Mar. 2016 Mar. 2017 Mar. 2018 Mar. 2019
5
13
28%
0%

413

300

49%

100

73

510

807
490

238

569
1,140

495

150

130
65

630

105

60
27%
17
46

711

SEMINARS & CONFERENCES

92
100

384

938
632

831

392

87

982

FY 2007 FY 2008 FY 2009 FY 2010 FY 2011 FY 2012 FY 2013 FY 2014 FY 2015 FY 2016 FY 2017 FY 2018

Visitors (Overseas) 65
Visitors (Domestic) 103
Visitors (Total)
168

100

58%

Overseas
Domestic% of Overseas% of Female

1,261

1,201

150

Researchers
Research Support Staffs
Administrative staffs
Total

Introduction

STAFF

105
131
44%
5%

98
147
40%
5%

105
150
41%
6%

90
169
35%
4%

102
150
41%
6%

111
163
41%
8%

136
143
49%
9%

0

Seminars
Conferences

156

140

4

7

11

24
4

156
7

140
11

196

232

222

216

24
21
17
13
14
11
14
12
11
FY 2007 FY 2008 FY 2009 FY 2010 FY 2011 FY 2012 FY 2013 FY 2014 FY 2015 FY 2016 FY 2017 FY 2018
16

186
16

196
12

232
11

249
14

246
13

222
17

184
14

192
11

216
21

Kavli IPMU Annual Report 20189

Introduction

TOTAL EXPENDITURE
519

500

480
449

450

449

90

422

400

68

49

250

347
60

57

300

236

350
69

67

75

78

78

81

67

150

70
60

252

3,372

3000

2,707

2,362

40
30

115

100

1000

20

50

10

9

FY 2007 FY 2008 FY 2009 FY 2010 FY 2011 FY 2012 FY 2013 FY 2014 FY 2015 FY 2016 FY 2017 FY 2018
Publications
9
115
202
236
252
347
350
480
449
449
422
519
% of international collaboration 49% 57% 68% 60% 67% 69% 67% 75% 78% 78% 81%

0

MEDIA COVERAGES AND OUTREACH ACTIVITIES
7,018

1200

500
0

1,225

1,524
1,366
896
25
25
288
132

48
112

911

3,902

1,842

1,866

3,425
3,262
1,301

425
92

2,991

1,024
1,259

538

489

96

90

117
88
404

231
80
234

486

486

444

825

906

987

1,027

1,101

453
93

397
91

387
82

653

574

619

335
119
295
104

1,023

1,006

948

494

408

388
635

3,041
783

846

1,410

2000
1500

2,844

2,844

2500

50

202

200

925

1,310

FY 2007 FY 2008 FY 2009 FY 2010 FY 2011 FY 2012 FY 2013 FY 2014 FY 2015 FY 2016 FY 2017 FY 2018
Personnel
Project Activities
Travel Expenses
Equipment
Other Research Project

BREAKDOWN OF FY 2018 TOTAL EXPENDITURE
7000

6,232

6,084

6000

1000

933

800

4,545
3,339

600

4,764

130
97
33

135
119
16

163
182

167

170

227

161

316
173

195

participants in outreach activities
media coverages (domestic)
media coverages (international)

Kavli IPMU Annual Report 2018

153
29

137
30

143
27

203

304

335
11.0 %

379
157

551

1,310
43.1 %

3000
2000

119
3.9 %

1000

222
143
34
7
0
0
FY 2007 FY 2008 FY 2009 FY 2010 FY 2011 FY 2012 FY 2013 FY 2014 FY 2015 FY 2016 FY 2017 FY 2018
47
40 0

783
25.8 %

4000

531
366

200

5,454 5000

3,340

400

1,376

5,581

382

3,277

10

3500

80

350

0

(%)
100

(1,000,000 JPY)

3,910

Introduction

PUBLICATIONS

494
16.2 %(1,000,000 JPY)
Personnel
Project Activities
Travel Expenses
Equipment
Other Research Project

Kavli IPMU Annual Report 201811

2News & Events 
July

OctoberJanuaryMay

AugustNovemberFebruary

June

September

December

March>> ALMA finds oxygen 13.28 billion light-years away>> Inner component of Japan’s upgraded particle
accelerator nears completion>> Public Lecture "Universe X World">> "Science and Metaphysics" by M. Gabriel>> Public lecture "Gravitational Waves and the Dark
Ingredients of the Universe">> RISTEX Symposium "An analysis of the factors that
influence women and girls to pursue physics andmathematics">> New Directions for LHC - Run 2 and Beyond>> MEXT Deputy Minister Yoichi Ito visited Kavli IPMU

Kavli IPMU    Annual Report 2018>> 1st lecture at "Science Cafe Universe 2018">> WPI Site Visit 2018>> Simulations uncover why supernova explosions ofsome white dwarfs produce so much manganeseand nickel>> Vertex algebras, factorization algebras andapplications>> Booth at the 2018 Super Science High SchoolStudent Fair>> UC Santa Cruz Chancellor visits Kavli IPMU>> Technetium-98 nuclear cosmochronometer
synthesized by supernova neutrinos>> 7th Hyper-Kamiokande Proto-Collaboration
Meeting>> IGM2018: Revealing Cosmology and Reionization
History with the Intergalactic Medium>> Cosmological constraints from the first-year Subaru
Hyper Suprime-Cam survey>> 2nd lecture at "Science Cafe Universe 2018">> Beyond the BSM (The 4th Kavli IPMU -Durham IPPP
-KEK -KIAS workshop)>> Caltech Professor Hirosi Ooguri appointed new
director of Kavli IPMU>> American Physical Society’s 2019 Hans A. Bethe
Prize goes to Ken’ichi Nomoto>> FOXSI-3 succeeds in focusing imaging
spectroscopic observation in soft x-rays from theSun for the first time>> Open Campus Kashiwa 2018>> Flavor Physics Workshop 2018>> Hirosi Ooguri awarded the 2018 Hamburg Prize for
Theoretical Physics>> Kavli IPMU/ICRR joint public lecture - "Particles,
Celestial Events, or the World of Mathematics">> “Actually I Really Love Physics! – Career Paths ofFemale Physics Graduates”>> Noncommutative deformations and moduli spaces>> Stellar Archaeology as a Time Machine to the First
Stars>> Kavli IPMU High School Student Event "Meet the
Scientists!">> Kavli IPMU staff commended at 2018 BusinessTransformation Awards for their smart tech>> 7th WPI Science Symposium "Transformative
Science"

News & Events

April 2018-March 2019

April>> Researchers studying the Universe will apply theirexpertise to cancer research>> Focus Week on Quantum Gravity and Holography>> Farthest star ever seen in the Universe detected>> 18th Kavli IPMU-ICRR Joint Public Lecture“Exploring Particles, Describing the Universe with
Particles”>> Study finds way to use quantum entanglement toanalyze black holes>> Next generation of telescope equipment begins
arriving in Hawaii>> Electrons and Positrons collide for the first time in
the SuperKEKB Accelerator

12News & Events>> Berkeley Week>> FOXSI-3’s initial data reveals the most accurate solar
corona data yet>> Kavli IPMU/ELSI/IRCN Joint Public Lecture:"A Question of Origins">> Hyper-K Proto-collaboration meeting and Near
Detector meeting>> Representation theory, gauge theory and integrable
systems>> Dark Matter may be hitting the Right Note in Small
Galaxies>> Visions for table-top dark matter experiments>> Upgraded SuperKEKB accelerator will start taking
data>> Masamune Oguri awarded this year’s Hayashi
Chushiro Prize>> Extremely Big Eyes on the Early Universe>> Hitoshi Murayama named University Professor

Kavli IPMU    Annual Report 201813

Kavli IPMU

Kavli IPMU Management

President

Makoto Gonokami

UTIAS

Director

Director: Masashi Haneda

Kavli IPMU External
Advisory Committee

Hirosi Ooguri

Administrative
Director

Deputy Directors

Tomiyoshi Haruyama

Deputy Administrative
Director

Hiroaki Aihara
Misao Sasaki
Tomiyoshi Haruyama

Yoshihide Sakai

Office for Research
Strategies

The Kavli IPMU has a rather unique organization. While
research is conducted in a flatstructure manner with loosely
defined grouping, the decision making is done in a top-down
scheme under the Director’s strong leadership. This scheme
minimizes the administrative load for the researchers. It is also
intended to maximally extract young researcher’s creativeand challenging minds as well as to encourage daily crossdisciplinary interactions.
The Director is appointed by the President of the University ofTokyo and reports directly to his office. The Director proposes
to hire the Principal Investigators to the President. For otherhiring of research staff and administrative staff, he has a complete authority. He is also solely responsible for making allother decisions. He is assisted by the three Deputy Directors
and the Administrative Director. They constitute the Executive Board (EB) and regularly meet to ensure smooth operation of the Institute. The EB has direct access to the Office of
the President for consultations on both scientific and administrative matters.

The Director is obliged to report the appointments of new
Principal Investigators and faculty members to the Director of
the University of Tokyo Institutes for Advanced Study (UTIAS).
Also, to clear the university formality in faculty hiring, the decisions of the Institute have to be endorsed by the Steering
Committee of the Kavli IPMU.
The Principal Investigators are world’s leading scientists intheir fields. They have a large autonomy in the research they
conduct. They can make proposals to the Director to hire
research staff at the Institute.

Organization

3

Organization

Organization

The External Advisory Committee (EAC), appointed by the
President of the University of Tokyo, reviews annually the scientific achievement and activities of the Institute and advises
the President on scientific priorities and the research activities
to keep the Institute stay on the course of its objectives.

Steering Committee
The External Advisory Committee Members (March 2019)

Executive Board
Chair

Hirosi Ooguri
Hiroaki Aihara
Misao Sasaki
Tomiyoshi Haruyama

Director
Deputy Director
Deputy Director
Administrative Director
   /Deputy Director

Mikhail Kapranov
Tsutomu Yanagida
Masahiro Takada
Mark Vagins

Principal Investigator
Principal Investigator
Principal Investigator
Principal Investigator

John Ellis
Giovanni Felder
Joshua Frieman
Masahiko Hayashi
Tatsuya Nakada
Youngbin Ruan
Sakura Schafer-Nameki
Nigel Smith

King's College London
ETH Zürich
FNAL/U Chicago; Chair
JSPS Bonn Office
EPFL
U Michigan
U Oxford
SNOLAB

Particle Theory
Mathematics
Astrophysics
AstronomyHigh Energy Experiment
Mathematics
Mathematical Physics
Astroparticle Physics

Kavli IPMU Research

Principal Investigators
Faculty, Postdocs, Students, Visitors

14

Kavli IPMU    Annual Report 2018

Kavli IPMU    Annual Report 201815

Organization

The main laboratory building on the Kashiwa Campus provides a basis for our researchers. Even most of experimentalists who are involved in Kamioka experiments and astronomical observations spend a good fraction of their time in
Kashiwa for analyzing data, sharing seminars and discussing
with theorists. The Kamioka Branch is a basis for the Kavli
IPMU staff members who are engaging in the undergroundexperiments conducted at the Kamioka underground laboratory. The Berkeley Satellite, besides being a place forresearch, serves as a contact place to the US scientific community. We also have close collaborative relations with several institutions both in Japan and overseas as well as withother departments within the University of Tokyo.

Host InstituteForeign institutions/consortia/programs having MOU with the Kavli IPMU

Collaborating Institutions(The Univ. of Tokyo)(domestic)

National Astronomical
Observatory in Japann
Department of Mathematicsn
Institute for Cosmic Ray Research(Kashiwa, Kamioka)n
Department of Physicsn
Department of Astronomy

Collaborating Institutions(overseas)

Department of Physics,
University of California, Berkeley, USA
Department of Astrophysical Sciences,
Princeton University, USA
Institut des Hautes
Etudes Scientifiques (IHES), France

16

Kavli IPMU    Annual Report 2018

Kavli IPMU
Kashiwa Campus
Kamioka Branch

Berkeley
Satellite

The Kavli IPMU holds close relations with similar research
institutions in the world for encouraging exchanges in
research and training of young research staff. We have signed
either an agreement or a memorandum of understanding
with those institutions.

Department of Physics,
Kyoto University
High Energy Accelerator
Research Organization (KEK)
Yukawa Institute for
Theoretical Physics,
Kyoto University

The University of California, Berkeley, Department of Physics
National Taiwan University, Leung Center for Cosmology and Particle Astrophysics (LeCosPA)
The Astrophysics Research Consortium [on the Sloan Digital Sky Survey III ]The Astrophysics Research Consortium [on the Sloan Digital Sky Survey AS3 (“After SDSS III”)]
The Astrophysics Research Consortium [on the Sloan Digital Sky Survey IV ]Garching/Munich Cluster of Excellence on “The Origin and Structure of the Universe”
UNIFY (Unification of Fundamental Forces and Applications) [under the EU’s Seventh Framework Program]
The Scuola Internationale Superiore di Studi Avanzati (SISSA)The Academia Sinica Institute of Astronomy and Astrophysics of Taiwan (ASIAA) [on the SuMIRe Project]
The Intermediate Palomar Transient Factory (iPTF)
Steklov Mathematical Institute, Russian Academy of Sciences
Center for Mathematical Sciences, Tsinghua University
The Tata Institute of Fundamental Research
TRIUMF (Canada’s National Laboratory for Particle and Nuclear Physics)
Deutsches Elektronen Synchrotron (DESY)
Princeton University
The University of Oxford, Department of Physics
The Kavli Institute for Astronomy and Astrophysics at Peking University (KIAA)
Le Centre National de la Recherche Scientifique (CNRS)The Mainz Institute for Theoretical Physics (MITP)
Johns Hopkins University

Organization

The Office for Research Strategies pursues external funds inorder to strengthen the research activities.

Research Center for
Neutrino Science,
Tohoku University
Institiute of Physical andChemical Research (RIKEN)
Institiute of Statistical
Mathematics (ISM)

Kavli IPMU    Annual Report 2018

17

4

Staff

Staff

Faculty Members

Director
Hitoshi Murayama, Particle Theory, (till 2018/10/14)
Hirosi Ooguri, Mathematical Physics (from 2018/10/15)

Deputy Directors
Hiroaki Aihara, High Energy Physics
Tomiyoshi Haruyama, High Energy Physics
Misao Sasaki, Cosmology

Principal Investigators
Hiroaki Aihara, (U Tokyo), High Energy Physics
Alexey Bondal, (Steklov Math. Inst.), Mathematics
Kentaro Hori, String Theory
Kunio Inoue, (Tohoku U), Neutrino Physics
Takaaki Kajita, (U Tokyo, ICRR), Neutrino Physics
Mikhail Kapranov, Mathematics

18

Kavli IPMU    Annual Report 2018

Stavros Katsanevas, (European Gravitational Observatory),
Experimental Physics
Masahiro Kawasaki, (U Tokyo, ICRR), Cosmology
Young-Kee Kim, (U Chicago), High Energy Physics
Toshiyuki Kobayashi, (U Tokyo, Math Sci), Mathematics
Toshitake Kohno, (U Tokyo, Math Sci), Mathematics
Eiichiro Komatsu, (MPI for Astrophysics), Cosmology
Kai Uwe Martens, Experimental Physics
Shigeki Matsumoto, Cosmology
Shigetaka Moriyama, (U Tokyo, ICRR), Neutrino Physics
Hitoshi Murayama, (UC Berkeley), Particle Theory
Masayuki Nakahata, (U Tokyo, ICRR), Astroparticle Physics
Hiraku Nakajima, Mathematics (from 2018/8/1)
Mihoko Nojiri, (KEK), Particle Theory
Yasunori Nomura, (UC Berkeley), Particle Theory
Hirosi Ooguri, (CALTECH), Mathematical Physics

Tomoyuki Abe, Mathematics
Alexey Bondal, (Steklov Math. Inst.), Mathematics (2018/8/1- 2019/2/15)
Mark Patrick Hartz, Neutrino Physics
Tomiyoshi Haruyama, High Energy Physics
Simeon John Hellerman, String Theory
Takeo Higuchi, High Energy Physics
Chiaki Hikage, Cosmology
Kentaro Hori, String Theory
Yukari Ito, Mathematics
Mikhail Kapranov, Mathematics
Nobuhiko Katayama, High Energy Physics
Alexandre Kozlov, Neutrino Physics
Khee-Gan Lee, Astronomy
Kai Uwe Martens, Experimental Physics
Shigeki Matsumoto, Cosmology
Tomotake Matsumura, Experimental Physics
Thomas Edward Melia, Theoretical Physics
Todor Eliseev Milanov, Mathematics
Surhud Shrikant More, Astronomy (till 2018/7/15)
Hitoshi Murayama, Particle Theory
Hiraku Nakajima, Mathematics
Takahiro Nishimichi, Cosmology (till 2018/12/31)
Yasunori Nomura, (UC Berkeley), Particle Theory (2018/6/8- 7/7)
Hirosi Ooguri, Mathematical Physics (from 2018/10/15)
Tadashi Orita, Experimental Physics
Misao Sasaki, Cosmology
Christian Schnell, (SUNY, Stony Brook), Mathematics(2018/6/25 - 8/17)
Satoshi Shirai, Particle Theory
John David Silverman, Astronomy
Hajime Sugai, Experimental Physics
Nao Suzuki, Astrophysics
Yoichiro Suzuki, Astroparticle Physics
Yuji Tachikawa, Particle Theory
Masahiro Takada, Cosmology
Tadayuki Takahashi, Experimental Physics
Shinichiro Takeda, Experimental Physics
Naoyuki Tamura, Astronomy
Yukinobu Toda, Mathematics
Mark Robert Vagins, Astroparticle Physics
Taizan Watari, Theoretical Physics
Atsushi Yagishita, Experimental Physics
Masahito Yamazaki, String Theory

Tsutomu Yanagida, Particle Theory
Naoki Yasuda, Astronomy
Hiromi Yokoyama, Science and Society
Naoki Yoshida, Astrophysics
Yutaka Yoshida, String Theory

Postdoctoral Researchers
Rodrigo Alonso De Pablo, Particle Theory (from 2018/10/1)
Metin Ata, Cosmology (from 2018/6/16)
Neil David Barrie, Particle Theory
Marco Bertolini, Particle Theory
Yalong Cao, Mathematics (from 2019/3/16)
Pietro Caradonna, Experimental Physics (from 2018/12/1)
Dmitry Chernyak, Experimental Physics
Peter Jonathan Cox, Particle Theory
Thomas Rafael Czank, Experimental Physics (from2018/12/1)
Matthew Dodelson, String Theory (from 2018/9/1)
William Ross Goodchild Donovan, Mathematics (till2018/5/31)
Anne Laure Marie Ducout, Cosmology
Martin Felix Fluder, String Theory (from 2018/9/16)
Shao-Feng Ge, Theoretical Physics
Chengcheng Han, Theoretical Physics
Jiaxin Han, Astronomy (till 2018/8/31)
Tilman Hartwig, Astrophysics (till 2018/11/30)
Seyed Morteza Hosseini, String Theory
Chang-Tse Hsieh, Theoretical Physics
Akishi Ikeda, Mathematics
Yuko Ikkatai, Science and Society
Shigeki Inoue, Astrophysics
Miho N. Ishigaki, Astronomy (till 2019/1/31)
Chen Jiang, Mathematics (till 2019/1/21)
Changwoo Joo, High Energy Physics
Daisuke Kaneko, High Energy Physics
Lalitwadee Kawinwanichakij, Astrophysics (from 2018/11/1)
Fabian Koehlinger, Cosmology
Robin Rinze Kooistra, Astronomy (from 2019/1/16)
Naoki Koseki, Mathematics
Tatsuki Kuwagaki, Mathematics
Juliana Kwan, Astrophysics (till 2018/9/30)
Chiara La Licata, Experimental Physics (from 2019/1/16)
Ting-Wen Lan, Astrophysics
Shing Chi Leung, Astronomy
Wentao Luo, Astrophysics (from 2018/7/16)
Oscar Macias, Astrophysics (from 2018/9/1)
Andrew William Macpherson, Mathematics
Ryu Makiya, Astronomy
Frederick Takayuki Matsuda, Experimental Physics
Hideaki Matsumura, Experimental Physics
Anupreeta Sadashiv More, Astronomy (till 2018/6/30)
Tomoko Morii, High Energy Physics
Yuki Moritani, Astronomy
Matthew Murdoch, Experimental Physics (till 2018/7/26)
Dinakar Muthiah, Mathematics (from 2018/9/1)
Kavli IPMU    Annual Report 2018

Staff

David Spergel, (Princeton U), Cosmology
Naoshi Sugiyama, (Nagoya U), Cosmology
Masahiro Takada, Cosmology
Tadayuki Takahashi, Experimental Physics
Yukinobu Toda, Mathematics
Mark Robert Vagins, Astroparticle Physics
Naoki Yoshida, (U Tokyo), Astrophysics

19

Yusuke Nakajima, Mathematics
Keigo Nakamura, Neutrino Physics (from 2018/10/1)
Taira Oogi, Astrophysics
Hyunbae Park, Cosmology (from 2019/1/16)
Youngsoo Park, Cosmology (from 2018/9/16)
Shi Pi, Astrophysics
Anna Puskas, Mathematics (from 2018/9/1)
Benjamin Pascal Jean-Marie Guillaume Quilain, Neutrino
Physics
Evangelos Routis, Mathematics (till 2018/9/30)
Ipsita Saha, Particle Theory (from 2018/11/16)
Yuki Sakurai, Experimental Physics
Francesco Sala, Mathematics
Kallol Sen, Theoretical Physics
Yota Shamoto, Mathematics
Atsushi Shimono, Astrophysics (till 2018/10/31)
Alessandro Sonnenfeld, Astrophysics (till 2018/8/31)
David Vincent Stark, Astronomy
Samantha Lynn Stever, Astrophysics (from 2019/2/1)
Naonori Sugiyama, Astronomy
Tomomi Sunayama, Cosmology
Ichiro Takahashi, Astronomy
Satoru Takakura, Astronomy
Michihisa Takeuchi, Particle Theory
Alexey Tolstov, Astrophysics (till 2018/9/30)
Po-Yen Tseng, Particle Theory
Wenting Wang, Astronomy
Matthias Weissenbacher, String Theory
John Welliaveetil, Mathematics (from 2018/11/1)
Jin Mann Wong, Theoretical Physics (till 2018/10/11)
Kenneth Christopher Wong, Astronomy (from 2018/9/1)
Benda Xu, Experimental Physics (till 2018/8/19)
Itamar Yaakov, Theoretical Physics (till 2018/8/31)
Kiyoto Yabe, Astronomy
Louis Yang, Particle Theory (till 2018/9/5)
Gabi Zafrir, Particle Theory

Support Scientist
Antonio Paladino, High Energy Physics (till 2018/5/31)

Joint Appointments
Sergey Blinnikov, (ITEP), Astronomy (2018/9/1-10/29)
Mark Patrick Hartz, (TRIUMF), Neutrino Physics (from2018/8/1)
Masashi Hazumi, (KEK), High Energy Physics
Yukari Ito, (Nagoya U), Mathematics
Alexander Kusenko, (UCLA), Particle Theory (2018/10/1512/25)
Hitoshi Murayama, (UC Berkeley), Particle Theory
Hirosi Ooguri, (CALTECH), Mathematical Physics (from2018/10/15)
Serguey Todorov Petcov, (SISSA), Particle Theory (2018/3/194/16,11/1-19,2019/3/7-4/22)
Edwin L Turner, (Princeton U), Astrophysics (2018/7/19-

20

Kavli IPMU    Annual Report 2018

8/5,10/29-11/16)
Naoki Yoshida, (U Tokyo), Astrophysics

Affiliate Members
Kou Abe, (U Tokyo, ICRR), Astroparticle Physics
Shin'ichiro Ando, (U Amsterdam), Astroparticle Physics
Bruce Berger, (Lawrence Berkeley National Laboratory),
Neutrino Physics
Melina Bersten, (CONICET), Astronomy
Sergey Blinnikov, (ITEP), Astronomy
Kevin Allen Bundy, (UC Santa Cruz), Astronomy
Andrew Bunker, (U Oxford), Astrophysics
Martin Gilles Bureau, (U Oxford), Astronomy
Scott Huai-Lei Carnahan, (U Tsukuba), Mathematics
Cheng-Wei Chiang, (Natl Taiwan U), Particle Theory
Yuji Chinone, (UC Berkeley), Astronomy
Neal K Dalal, (Perimeter Institute), Astrophysics
Patrick Decowski, (U Amsterdam/GRAPPA), Neutrino Physics
Jason Detwiler, (U Washington, Seattle), Neutrino Physics
Mamoru Doi, (U Tokyo, IoA), Astronomy
Chris Done, (Durham U), Astrophysics (from 2018/7/1)
Yuri Efremenko, (U Tennessee), Neutrino Physics
Tohru Eguchi, (Rikkyo U), Field Theory (till 2019/1/30)
Motoi Endo, (KEK), Particle Theory
Sanshiro Enomoto, (U Washington, Seattle), Neutrino Physics
Andrea Ferrara, (Scuola Normale Superiore di Pisa),
Astronomy
Gaston Folatelli, (CONICET), Astrophysics
Andreu Font-Ribera, (UCL), Cosmology
Brian Fujikawa, (LBL, Berkeley), Neutrino Physics
Kenji Fukaya, (SCGP), Mathematics
Masataka Fukugita, (U Tokyo), Astrophysics
Koichi Hamaguchi, (U Tokyo), Particle Theory
Jiaxin Han, (Shanghai Jiao Tong U), Astronomy (from2018/9/1)
Tilman Hartwig, (U Tokyo), Astrophysics (from 2018/12/1)
Tetsuo Hatsuda, (RIKEN), Nuclear Physics
Yoshinari Hayato, (U Tokyo, ICRR), Neutrino Physics
Karsten Heeger, (Yale U), Neutrino Physics
Katsuki Hiraide, (U Tokyo, ICRR), Astroparticle Physics
Raphael Hirschi, (Keele U), Astronomy (till 2018/12/31)
Junji Hisano, (Nagoya U), Particle Theory
Glenn Horton-Smith, (Kansas State U), Neutrino Physics
Shinobu Hosono, (Gakushuin U), Mathematical Physics
Masahiro Ibe, (U Tokyo, ICRR), Particle Theory
Koichi Ichimura, (U Tokyo, ICRR), Astroparticle Physics
Hirokazu Ikeda, (JAXA), Experimental Physics (from2018/9/1)
Motoyasu Ikeda, (U Tokyo, ICRR), High Energy Physics
Shiro Ikeda, (ISM), Mathematics
Yoshiyuki Inoue, (RIKEN), Astrophysics (from 2018/7/1)
Ken'ichi Izawa, (Tokushima U), Particle Theory
Chang Kee Jung, (SUNY, Stony Brook), High Energy Physics(till 2018/11/29)

Jun Kameda, (U Tokyo, ICRR), Neutrino Physics
Yousuke Kanayama, (RIKEN), Experimental Physics (from2018/9/1)
Amanda Irene Karakas, (Monash U), Astronomy
Masaki Kashiwara, (Kyoto U), Mathematics
Akishi Kato, (U Tokyo, Math Sci), Mathematical Physics
Yasuyuki Kawahigashi, (U Tokyo, Math Sci), Mathematics
Edward T. Kearns, (Boston U), Neutrino Physics
Sergey Ketov, (Tokyo Metropolitan U), High Energy Physics
Nobuhiro Kimura, (KEK), High Energy Physics
Anatol N. Kirillov, (Kyoto U), Mathematics
Yasuhiro Kishimoto, (Tohoku U), Neutrino Physics
Ryuichiro Kitano, (KEK), Particle Theory
Chiaki Kobayashi, (CAR, U of Hertfordshire), Astronomy
Kazuyoshi Kobayashi, (U Tokyo, ICRR), Astroparticle Physics
Masayuki Koga, (Tohoku U), Neutrino Physics
Satoshi Kondo, (Middle East Technical U), Mathematics
Yusuke Koshio, (Okayama U), Neutrino Physics
Alexander Kusenko, (UCLA), Particle Theory
Alexie, Solange Leauthaud Harnett, (UC Santa Cruz),
Astrophysics
Shiu-Hang (Herman) Lee, (Kyoto U), Astrophysics (from2018/9/1)
Si Li, (Tsinghua U), Mathematical Physics
Marco Limongi, (INAF), Astrophysics
Keiichi Maeda, (Kyoto U), Astrophysics
Kazuo Makishima, (U Tokyo), High Energy Physics
Brice Menard, (Johns Hopkins U), Astrophysics
Makoto Minowa, (U Tokyo ), Experimental Physics
Makoto Miura, (U Tokyo, ICRR), High Energy Physics
Hironao Miyatake, (Nagoya U), High Energy Physics
Hiroshi Mizuma, (RIKEN), Experimental Physics (from2018/9/1)
Anupreeta Sadashiv More, (IUCAA), Astronomy (from2018/7/1)
Surhud Shrikant More, (IUCAA), Astronomy (from 2018/7/16)
Takeo Moroi, (U Tokyo), Particle Theory
Tomoki Morokuma, (U Tokyo, IoA), Astronomy
David Robert Morrison, (UC Santa Barbara), Mathematics(from 2019/1/15)
Shinji Mukohyama, (Kyoto U), Gravity
Motohico Mulase, (UC Davis), Mathematics
Kentaro Nagamine, (Osaka U), Astrophysics (from 2018/5/1)
Yasuhiro Nakajima, (U Tokyo, ICRR), Neutrino Physics
Kengo Nakamura, (Tohoku U), Neutrino Physics
Kenzo Nakamura, (KEK), Neutrino Physics
Tsuyoshi Nakaya, (Kyoto U), High Energy Physics
Kazunori Nakayama, (U Tokyo), Cosmology
Shoei Nakayama, (U Tokyo, ICRR), Neutrino Physics
Yu Nakayama, (Rikkyo U), Theoretical Physics
Ken'ichi Nomoto, (U Tokyo ), Astronomy
Hirokazu Odaka, (U Tokyo), High Energy Astrophysics (from2018/9/1)
Masamune Oguri, (U Tokyo), Cosmology

Shinnosuke Okawa, (Osaka U), Mathematics
Kimihiro Okumura, (U Tokyo, ICRR), Neutrino Physics
Teppei Okumura, (Academia Sinica), Cosmology
Yoshiyuki Onuki, (U Tokyo, ICEPP), High Energy Physics
Masaki Oshikawa, (U Tokyo, ISSP), Theoretical Physics
Masami Ouchi, (U Tokyo, ICRR), Astronomy
Andrei Pajitnov, (U Nantes), Mathematics
Myeonghun Park, (SEOULTECH), Particle Theory
Serguey Todorov Petcov, (SISSA), Particle Theory
Andreas Piepke, (U Alabama), Neutrino Physics
Jason Xavier Prochaska, (UC Santa Cruz), Astronomy
Robert Michael Quimby, (San Diego State U), Astronomy
Jason Rhodes, (NASA JPL/Caltech), Cosmology
Wiphu Rujopakarn, (Chulalongkorn U.), Astronomy
Kyoji Saito, (Kyoto U), Mathematics
Yoshihisa Saito, (Rikkyo U.), Mathematics
Yoshio Saito, (U Tokyo, ICRR), High Energy Physics
Hidetaka Sakai, (U Tokyo, Math Sci), Mathematics
Katsuhiko Sato, (JSPS), Astroparticle Physics
Christian Schnell, (SUNY, Stony Brook )Kate Scholberg, (Duke U), Neutrino Physics
Hiroyuki Sekiya, (U Tokyo, ICRR), Astroparticle Physics
Masato Shiozawa, (U Tokyo, ICRR), High Energy Physics
Aurora Simionescu, (SRON Netherlands Inst. For Space
Research), Astrophysics (from 2018/7/1)
Fedor Smirnov, (LPTHE), Mathematics
Michael Smy, (UC Irvine), Neutrino Physics
Charles Louis Steinhardt, (U Copenhagen), Astronomy
James L. Stone, (Boston U), High Energy Physics
Shigeki Sugimoto, (Kyoto U), Theoretical Physics
Toshikazu Suzuki, (U Tokyo, ICRR), Gravity
Atsushi Takahashi, (Osaka U), Mathematics
Fuminobu Takahashi, (Tohoku U), Particle Theory
Tadashi Takayanagi, (Kyoto U), String Theory
Atsushi Takeda, (U Tokyo, ICRR), Astroparticle Physics
Yasuhiro Takemoto, (U Tokyo, ICRR), Experimental Physics
Yasuo Takeuchi, (Kobe U), Astroparticle Physics
Hidekazu Tanaka, (U Tokyo, ICRR), Neutrino Physics
Masaomi Tanaka, (Tohoku U), Astronomy
Atsushi Taruya, (Kyoto U), Astrophysics
Takayuki Tomaru, (NAOJ), Experimental Physics
Nozomu Tominaga, (Konan U), Astrophysics
Werner Tornow, (Duke U), Neutrino Physics
Akihiro Tsuchiya, (Nagoya U), Mathematics
Sachiko Tsuruta, (Montana State U), Astrophysics
Edwin L Turner, (Princeton U), Astrophysics
Akitoshi Ueda, (NAOJ), Astronomy
Kazushi Ueda, (U Tokyo, Math Sci), Mathematics
Hokuto Uehara, (Tokyo Metropolitan U), Mathematics
Mikhail Verbitsky, (HSE, National Research U), Mathematics
Alexander Voronov, (U Minnesota), Mathematics
Christopher W. Walter, (Duke U), Neutrino Physics
Shin Watanabe, (JAXA), Experimental Physics
Bryan Webber, (U Cambridge), Particle Theory
Kavli IPMU    Annual Report 2018

Staff

Staff

21

StaffGraduate Students
Kazuyuki Akitsu, Cosmology
Kenta Ando, Particle Theory
Laurence Cook, (U Oxford), Neutrino Physics (from2018/10/1)
Yuichi Enoki, Particle Theory
Hajime Fukuda, Particle Theory
Kento Furukawa, Experimental Physics
Tommaso Ghigna, (U Oxford), Astroparticle Physics
Alexander Goldsack, (U Oxford), Neutrino Physics (from2018/7/25)
Fuminori Hasegawa, Particle Theory
Taku Hayakawa, Particle Theory (till 2018/5/14)
Jeong Pyong Hong, Theoretical Physics (till 2018/5/14)
Shunichi Horigome, Particle Theory
Benjamin Aaron Horowitz, (UC Berkeley), Theoretical Physics(till 2019/1/14)
Takumi Ichikawa, Particle Theory
Keisuke Inomata, Theoretical Physics
Hikaru Ito, Cosmology
Keita Kanno, Particle Theory
Taisuke Katayose, Theoretical Physics
Miho Katsuragawa, Experimental Physics
Tenyo Kawamura, Experimental Physics
Nozomu Kobayashi, Particle Theory
Shin Kobayashi, Particle Theory
Yosuke Kobayashi, Cosmology
Asahi Kojima, Particle Theory
Toshiki Kurita, Theoretical Physics
Yasunori Lee, Particle Theory
Xiangchong Li, Cosmology
Alexander Nicholas Mason, (U Oxford), Particle Theory
Kai Murai, Particle Theory (from 2018/5/14)
Ryoma Murata, Cosmology
Wakutake Nakano, Theoretical Physics
Hiromasa Nakatsuka, Particle Theory
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22

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Kavli IPMU    Annual Report 201823

5

Research HighlightS

Research Highlights

A mysterious Kac-Moody factor - Anna Puskás researchhighlight article
August 29th , 2019.

24

th
may
be 29
finite,affine or of general Kac-Moody type. Often an object that is well understood
August, 2019.
in the finite context is much more subtle in the infinite dimensional setting.
Considerroots and
their multiplicities
for a simple
example. inA nature
finite root
Lie groupsimaginary
and Lie algebras
underly
many of the interesting
symmetries
andsystemhas no imaginary
roots.
typeistheimaginaryrootssystems.
are all integer
multiplesmathematics.
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Lieaffinealgebras
governedby root
A rootsystemAnnaofa single
minimalrootKac-Moody
and all have type.
multiplicity
one.
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generaltypes
may
be finite,affineimaginary
or of general
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well understoodtheimaginaryroots areharderto characterize
a closed
formula for
their multiplicity is
in Liethefinite context
is muchmore
subtle in theandinfinitedimensionalsetting.
groups and Lie algebras underlie many of the interesting symmetries in nature and mathematics. The structure of Lienotalgebras
known.
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roots
and
their
multiplicitiesforasimpleexample.
finiteroot
is governed by root systems. A root system may be finite, affine or of general Kac-Moody type.AOftenan object
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becomemore
complexwhen
movingto affinefrommultiples
affine tosystemhasunderstoodnoroots.
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thein imaginary
roots
are
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context
more
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identityabout
thePoincaréof Consider
a general
singleimaginary
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and
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have
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as an
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noteralknown.
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whenmovingwhen
from finiteto
affineand from
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toα affine

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−
te
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Macdonald's
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the Weyl group
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beautiful
identitythe
Poincaré
1 − eαexample. (Hereis theWeyl
length function.)+w∈Ww∈W rootα∈Φpolynomialofℓthegroup
W of a finite
systemΦ as an example. (Here  is thelengthfunction.)
This formula
no longer holds in the infinite dimensionalsetting.
on the right-hand Instead+side one must introduce a correction
factorreplace m and
1 − teαthe set Φ of all positive rootst(w) =This mwis supported αon positive imaginary roots andwith the set of all positive real roots.
1−e
w∈W
w∈W
α∈Φ+
is invariant under the Weyl group.
Thisfactor nom appears
in many
formulasthe theory of
infiniteInstead
dimensionalThis
formulalonger holds
in theinfiniteindimensionalsetting.
on theKac-Moodyright-hand+
LieThisalgebrasoverp-adicThedimensional
factorm setting.
ismtheanddiscrepancy
betweenthecorrect
expressionofallpositive
roots
side
one
must
introduce
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inathecorrection
infinite
Insteadon thetheright-handonemust
introducea cor+
ofall positive
thefinite-dimensional
set of all on
positive
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rectionm
replacesetфgeneralization
and
what
would
the thenaive
formula.
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set
ofand
allbe
positiverealroots.
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mofwithis thesupported
positive
imaginaryrootsis andpositive
imaginary
roots
and
is
invariant
under
the
Weyl
group.
casefor the underaffine theGindikin-Karpelevich
formula by Braverman-Garland-Kazhdan-Patnaik
is invariant
Weyl group.
Thisfactormthe
appears
in many
formulasthetheory of infinite
Kac-MoodyLiealgebrasover[BKP16],
p-adicfields.and
The[BGKP14],versionof in
Macdonald’s
for thespherical
functionThisfactormaffineappears
in many
formulasinformulathedimensional
theoryofinfinitedimensional
Kac-Moodyfactormisthediscrepancy
betweenthecorrect
expression
and
what
would
be
the
naive
generalizationofthefinitetheinfinite dimensional
analogue
the Casselman-Shalika[Pat17].
A versionof m
Lie algebras
over p-adic fields.
Theoffactor
m is the discrepancyformula
betweenthe correct
expression
dimensional
formula. root
is system
the case foristheaffine Gindikin-Karpelevich
formulawith
by Braverman-Garland-Kazhdan-Patnaik
for
awhat
metaplectic
featured
in my
joint
work
Patnaikon theThis
metaplecand
would
beThisthenaive generalizationof thefinite-dimensional
formula.
is the[BGKP14], the affine version of Macdonald's formula for the spherical function [BKP16], and the infinite dimensional anatic
Casselman-Shalika
formula[PP19].
Gaussent, and Rousseau
caseKac-Moodyfor the affine
Gindikin-Karpelevich
formulaby Bardy-Panse,
Braverman-Garland-Kazhdan-Patnaik
logue of the Casselman-Shalika formula [Pat17]. A version of m for a metaplectic root system is featured in my joint work
[BPGR16,
Theorem
7.3]
generalize
Macdonald’s
formulaforthespherical
function
beyond[BGKP14],theaffineversionof
Macdonald’s
formulaforthespherical
function[BKP16],andwith Patnaik on the metaplectic Kac-Moody Casselman-Shalika formula [PP19]. Bardy-Panse,
Gaussent,
and Rousseau
affinetypes,
and7.3]
mgeneralize
playsanalogueaMacdonald's
similarofrole
thereassphericalwell. functionformulathe[BPGR16,
infinitedimensionalthe
Casselman-Shalika[Pat17].
A versionof m
Theoremformulafor thebeyond affine
types, andm plays a similar
Havingagoodunderstanding
of
m
would
thereforemeanabettergrasp
theimportantforrolea theremetaplecticrootsystemisfeatured
in
my
joint
work
with
Patnaikonmetaplecas well.
formulasit appears
in. However,determining
m onis thea hardquestion.
affineticHaving
Kac-Moody
Casselman-Shalika
formula[PP19].
Bardy-Panse,
Gaussent,
Rousseaua goodunderstandingof m wouldexactly
therefore
mean
a better grasp
importantformulasIn
itandappearsin.types,
Howitscomputation
turns
toquestion.
be equivalent
toitsformula
Macdonald’s
Constant
Term
Conjecture,[BPGR16,
7.3]
Macdonald’s
forturns
thespherical
function
beyondever,
exactlyTheorem
determining
m isout
ageneralize
hard
In affine types,
computationout
to be equivalenttoMacdonald's
Constant
Conjecture,which
solvedby Cherednik[Che95,
Mac82]. m
Howeveris yet moremysteriousbeyond
beyondwhich
wasTerm
solvedbyplays
Cherednik[Che95,
Mac82].
Howeveris yetmmore
mysterious
affinetypes,
andma wassimilar
role
there
as
well.
affinetype.aIngood
joint
work
with
Dinakar
Ian
Whitehead,
wemeaninvestigatedm in Kac-Moody[MPW18].
affine
type.
In
joint
work
withMuthiah
DinakarMuthiahand
Ian Whitehead,
we investigatedm in
Havingunderstandingof m andwould
therefore
a bettergrasp
on+generality
the important.
The
correction
factormcanbewrittenasaninfiniteproductoverthepositive
imaginary
root
cone
Q
im
Kac-Moody
generality
formulasit appears
in. [MPW18].
However, exactly determining m is a hard question. In affine types,
correction turns
factor out
m can
as antoinfinite
productConstantover the positive
imaginary
itsThecomputation
to be
be written
equivalent
Macdonald’s
Term Conjecture,+rootwhichcone
wasQsolved
by Cherednik [Che95, Mac82]. However m is yet more mysterious beyondim .
 n λ −m(λ,n)
affine type. In joint work withmDinakar
Muthiah=(1 − tande ) Ian Whitehead, we investigated m in
Kac-Moody generality [MPW18].
n≥0
λ∈Q+
im
The correction factor m can be written
as an infinite product over the positive imaginaryn+ exponents m(λ, n) can be collected into a polynomial. mλ (t) =
For
each
λ
the
root cone Qim .
n≥0 m(λ, n)tComputing m is equivalent to determining the polynomial
m (t) for every λ ∈ Q+
im . The(1 − tn eλ )−m(λ,n) λm=constant term mλ (0) agrees with the +multiplicity of the root λ. Therefore computing mn≥0
imincludes the question of determiningλ∈Qmultiplicities
of imaginary roots.

ForThougheach λ them(λ, isn)available,
can be collected
intomethodsa polynomial.
mλ (t) =
m(λ,
n)tn
prove
no exponents
closed formula
there areto computemλ (t).
n≥0We
a generalization
the 2018
Petersonalgorithm [MPW18,
Sectionthe Berman-Moody
Computing
is ofequivalent
to determining
the polynomialmλ5.](t) andfor every
λ ∈ Q+
Kavli IPMU m
AnnualReportim . The1of the root λ. Therefore computing m
constant term mλ (0) agrees with the multiplicity

References[1] A. Braverman, H. Garland, D. Kazhdan, and M. M. Patnaik, An affine Gindikin-Karpelevich formula, Perspectives in representation theory, Contemp. Math., vol. 610, Amer. Math. Soc., Providence, RI, 2014, pp. 43–64.
[2] A. Braverman, D. Kazhdan, and M. M. Patnaik, Iwahori-Hecke algebras for p-adic loop groups, Invent. Math. 204 (2016),
no. 2, 347–442.
[3] N. Bardy-Panse, S. Gaussent, and G. Rousseau, Iwahori-Hecke algebras for Kac-Moody groups over local fields, Pacific
J. Math. 285 (2016), no. 1, 1–61.
[4] I. Cherednik, Double affine Hecke algebras and Macdonald's conjectures, Ann. of Math. (2) 141 (1995), no. 1, 191–216.
[5] I. G. Macdonald, Some conjectures for root systems, SIAM J. Math. Anal. 13 (1982), no. 6, 988–1007.
[6] D. Muthiah, A. Puskás, and I. Whitehead, Correction factors for Kac-Moody groups and t-deformed root multiplicities, toappear in Math. Z., arXiv preprint arXiv:1806.05209 (2018).
[7] M. M. Patnaik, Unramified Whittaker functions on p-adic loop groups, Amer. J. Math. 139 (2017), no. 1, 175–213.
[8] M. M. Patnaik and A. Puskás, Metaplectic covers of Kac–Moody groups and Whittaker functions, Duke Math. J. 168 (2019),
no. 4, 553–653.

Kavli IPMU Annual Report 2018

Research Highlights

ALie
mysterious
factorAnna symmetries
Puskás inresearchgroups and Lie Kac-Moody
algebras underly manyof the -interesting
nature andmathematics.
The
structureKac-Moodyof Lie algebrasFactor
is governed by root systems. A root system
highlight
article5.1 A Mysteriousn

For each λ the exponents m(λ, n) can be collected into a polynomial. mλ(t) = ∑ n≥0 m(λ, n)tComputing m is equivalent to determining the polynomial mλ(t) for every λ ∈ Q +im . The constant term mλ(0) agrees withthe multiplicity of the root λ. Therefore computing m includes the question of determining multiplicities of imaginary
roots.
Though no closed formula is available, there are methods to compute mλ(t). We prove a generalization of the Peterson
algorithm [MPW18, Section 5.] and the Berman-Moody formula [MPW18, Theorem 6.5] to compute not only multiplicities
2of roots λ but the entire polynomial mλ(t). Furthermore, mλ(t) turns out to be divisible by (1−t) for any Kac-Moody rootsystem [MPW18, Theorem 7.6]. In the affine case the quotient carries information about the corresponding Lie algebra.
However the meaning and approximate size of the non-constant coefficients of this quotient remains a mystery beyond
the affine setting.

25

Research Highlights

5.2 Cosmology from Cosmic Shear Power Spectra
Using Subaru Hyper-Suprime Cam Data

5.3 Coulomb Branches of Quiver Gauge Theories
with Symmetrizers
Hiraku Nakajima

S8 ≡ σ8(Ωm/0.3)0.45

The Λ Cold Dark Matter ( ΛCDM) model has been established as the standard cosmological model to describe the expansion history and the growth of the large-scale structure of the Universe. However, we are challenged by a fundamental lackof physical understanding of the main components of the Universe, dark matter and cosmological constant Λ or moregenerally dark energy. Coherent distorted pattern of distant galaxy images by gravitational lensing of large-scale structure,commonly referred to as the cosmic shear signal, is a unique probe of the total matter distribution in the Universe including
dark matter. Cosmic shear is especially sensitive to the combination of the matter density parameter Ωm and the amplitude
αparameter of matter fluctuationsσ8, i.e., S8(α) ≡σ8(Ωm/0.3) with α ~ 0.5.
We measure cosmic weak lensing shear power spectra with the Subaru Hyper Suprime-Cam (HSC) survey first-year shear
2
catalog covering 137 deg of the sky. The HSC survey is unique due to the combination of its depth ( 5σ point-source depthof the Wide layer of і ~ 26 ) and excellent image quality (typical і-band seeing of ~ 0.”58), which enable us to measure cosmic
shear signals up to higher redshifts with lower shape noise than current lensing survey such as KiDS and DES. Thanks to the−2high effective galaxy number density of 16.5 arcmin even after conservative cuts such as magnitude cut of і < 24.5 andphotometric redshift cut of 0.3 ≤ z ≤ 1.5, we obtain a high significance measurement of the cosmic shear power spectra in
4 tomographic redshift bins, achieving a total signal-to-noise ratio of 16 in the multipole range 300 ≤ℓ≤ 1900.
In order to obtain robust cosmological constraints from cosmic shear measurements, we perform a blind analysis to avoid
confirmation biases affecting our results. We carefully account for various uncertainties in our analysis including the intrinsic alignment of galaxies, scatters and biases in photometric redshifts, residual uncertainties in the shear measurement, andmodeling of the matter power spectrum. The accuracy of our power spectrum measurement method as well as our analytic model of the covariance matrix are tested against realistic mock shear catalogs.
+0.029αFor a flat ΛCDM model, we find S8≡σ8 (Ωm/0.3) = 0.800 −0.028 for α = 0.45 from our HSC tomographic cosmic shear analysis
alone. We find that the effect of possible additional systematic errors can shift the best-fit valuesof S8 by up to ~ 0.6 σ. In comparison with Planck
HSC Y1DES Y11.0
cosmic microwave background constraints, ourPlanck TT+lowP
KiDS450
results prefer slightly lower values of S8 , as shownin Figure 1. Such lower best-fit values of S8 and Ωm
0.9
are also found in other recent weak lensing analyses including KiDS and DES. Although our consistency analysis based on the Bayesian evidence
0.8
ratio test indicates that these lower values could
just be a statistical fluctuation, there is a possibility
0.7that these lower values originate from systematiceffects that are unaccounted for in our current
cosmic shear analysis, or more interestingly, from apossible failure of our fiducial neutrino mass-freeΛCDM model. The full HSC survey data will contain several times more area, and will lead to significantly improved cosmological constraints.
Reference[1] C. Hikage et al. 2019, PASJ, 71, 43

26

Kavli IPMU Annual Report 2018

0.1

0.2

0.3

0.4

Ωm
Figure 1: Marginalized posterior contours in the Ωm -S8 ( α = 0.45 )plane,
where S8 ( α ) ≡ σ8 ( Ωm / 0.3)α , in the fiducial ΛCDM model. Both
68% and 95% credible levels are shown. For comparison, we plot
cosmic shear results from KiDS- 450 with correlation function (CF)estimators, DES Y1, as well as Planck 2015 CMB constraints without
CMB lensing.

Coulomb branch of a supersymmetric gauge theory in 3 dimension had been studied by physicists for many years, but its
mathematically rigorous definition was given only recently by my joint work with Braverman and Finkelberg [1] based on
my earlier work [3]. The construction uses the convolution product, a standard technique in geometric representation
theory, applied to a certain infinite dimensional space arising from the gauge theory. An interesting byproduct of thisconstruction is a natural quantization of Coulomb branch, that is a noncommutative algebra deforming the ring of functions on Coulomb branch. Study of its representation theory is a currently hot topic, and new unexpected phenomena
have been found.
Quiver gauge theories form an interesting family of gauge theories, whose Coulomb branches and quantization have beenstudied most intensively [2]. Here a quiver is a finite oriented graph, such as◦→◦→◦. The corresponding SUSY gauge
theory is given by putting connections on ◦, and bifundamental matter fields on →. Quiver gauge theories have close
connection with the theory of Kac-Moody Lie algebras associated with the Dynkin diagram of the underlying quiver. For
example, the above example gives sl(4) whose Dynkin diagram is ◦―◦―◦. Quantization of Coulomb branch is the socalled truncated shifted Yangian, which is roughly a deformation of the loop algebra of the Kac-Moody Lie algebra.
This construction realizes only symmetric Kac-Moody Lie algebras, as the orientation of arrows in the original quiver is forgotten in the Dynkin diagram. For example, the Dynkin diagram◦―◦⇒◦of so(7) does not appear in this construction.
In my recent joint work with Alex Weekes [4], I modify the definition of Coulomb branch so that it is related to a symmetrizable Kac-Moody Lie algebra, such as the above◦―◦⇒◦. The corresponding quiver gauge theory is still for◦→◦→◦,
but we modify the spacetime on which connections and matter fields are defined. Namely connections are defined on the222-dimensional sphere S , the boundary of a small ball in 3-dimensional space. In the new construction S could be different22
for each◦. The S for the rightmost◦is the two-fold covering of the S for the left two◦’s. Matter fields are considered after
pulling back the connection for the left◦.

Research Highlights

Chiaki Hikage

We also study representation theory of quantization of these new Coulomb branches, which are truncated shifted Yangianfor symmetrizable Kac-Moody. Rather surprisingly, although quantization itself is new as an algebra, its representation
theory is essentially the same as the representation theory of a quantization of the Coulomb branch corresponding to asymmetric Kac-Moody Lie algebra. For example, one for ◦―◦⇒◦is the same as one for ◦―◦―◦―◦―◦. A similar
relation was found earlier by Frenkel-Hernandez, Kashiwara-Kim-Oh, and our construction gives its conceptual explanation.

References[1] A. Braverman, M. Finkelberg and H. Nakajima, Towards a mathematical definition of Coulomb branches of 3-dimensional N=4 gauge theories, II, Advances in Theoretical and Mathematical Physics, 22 (2018), No. 5, 1071–1147.
[2] A. Braverman, M. Finkelberg and H. Nakajima, Coulomb branches of 3d N=4 quiver gauge theories and slices in theaffine Grassmannian, with appendices by A. Braverman, M. Finkelberg, J. Kamnitzer, R. Kodera, H. Nakajima, B. Webster,and A. Weekes, preprint, arXiv:1604.03625.
[3] H. Nakajima, Towards a mathematical definition of Coulomb branches of 3-dimensional N=4 gauge theories, I, Advances in Theoretical and Mathematical Physics, 20 (2016), No. 3, 595–669.
[4] H. Nakajima and A. Weekes, Coulomb branches of quiver gauge theories with symmetrizers, preprint, arXiv:1907.06552.

Kavli IPMU Annual Report 201827

Research Highlights

5.5 Mapping the High-Redshift Cosmic Web
in 3D
Hirosi Ooguri

The unification of quantum mechanics and general relativity is relevant for many questions we study at the Kavli IPMU.
They include the origin of the dark energy, the mechanism of the cosmic inflation in the early universe, and the initial conditions of the universe. One of the important tools theorists use in this context is the low energy effective theory. In theories
without gravity, it is generally believed that any low energy effective theory that satisfies a minimum set of requirements
such as the unitarity and causality within the low energy region should have consistent ultraviolet completion. However,
over the last ten years or so, several evidences have emerged suggesting that the situation with gravity is different. Thereseems to be a set of low energy effective theories including gravity which cannot be realized as low energy limits of mathematically consistent quantum theories. Such a set of low energy effective theories was named the Swampland by Cumrun
Vafa in 2005 [1]. One can think of the Swampland as a complement of the Landscape of String Vacua in the space of all
possible low energy effective theories. Since then, several conditions have been proposed to delineate the Landscape andthe Swampland, which are called Swampland Conditions.
In his 2006 paper [2] with Vafa, Ooguri formulated a Swampland Condition about the space of scalar fields, which has
been called the Distance Conjecture. Around the same time, another called the Weak Gravity Conjecture was also proposed in [3]. These two conditions have been tested affirmatively in numerous top-down constructions in string theory.
Moreover, surprising connections has emerged between them and to other conjectures such as the Cosmic Censorship
Hypothesis.
There is even an older conjecture about quantum gravity. It is that quantum gravity cannot have global symmetry. Thisconjecture was proposed decades ago based on the behavior of the Hawking radiation from a black hole and the statisticalinterpretation of the Bekenstein-Hawking entropy formula, but it had not been proven. Since 2015, Ooguri has been working with Daniel Harlow, now an assistant professor at MIT, to prove this conjecture in the context of the AdS/CFT correspondence, which is the only setup where quantum gravity is well-defined. In the fall of 2018, they published two papers,
a 5 page announcement [4] of the proof and another 175 paper full exposition [5] of the proof. Their proof makes essential
use of the deep connection between the holography of quantum gravity and quantum error corrections in quantum
information theory. The short announcement was published in Physical Review Letters and was chosen for its Editors
Suggestion.
One of the outstanding mysteries of the universe is the origin of the dark energy, which is responsible for the accelerative
expansion. Another is the mechanism of the cosmic inflation in the early universe. Both can be described by the de Sitter
solution to the Einstein equations. However, it has been challenging to give a top-down construction of a de Sitter solution
from string theory. In the summer of 2019, Ooguri with Georges Opied, Lev Spodyneiko, and Cumrun Vafa, formulated aconjecture about the scalar potential in a low energy effective theory in the Landscape [6]. It is called the de Sitter conjecture since it excludes the de Sitter solution as an exact solution to string theory. The paper became the highest cited paperin high energy theory in 2019, partly because it gave a new direction to phenomenological model building and partly
because it inspired string theorists to go back to re-examine earlier attempts to construct the de Sitter solution. Subsequently, Ooguri with Eran Palti, Gary Shiu, and Cumrun Vafa, showed that the de Sitter conjecture related to the distanceconjecture and reformulated the conjecture [7]. The Swampland Conditions do not exclude the cosmic inflation, but they
put non-trivial constraints on inflation models with observable consequences. It is hoped that these conjectures can betested in experiments over the next decades such as the LiteBIRD project.
References[1] C. Vafa, “The String Landscape and the Swampland,” hep-th/0509212.
[2] H. Ooguri and C. Vafa, “On the Geometry of the String Landscape and the Swampland,” Nucl. Phys. B766 (2007) 21.
[3] N. Arkani-Hamed, L. Motl, A. Nicolis, and C. Vafa, “The String Landscape, Black Holes and Gravity as the Weakest Force,”
JHEP 0706 (2–7) 060.
[4] D. Harlow and H. Ooguri, “Constraints on Symmetries from Holography,” Phy. Rev. Lett. 122 (2019) 191601.
[5] D. Harlow and H. Ooguri, ”Symmetries in Quantum Field Theory and Quantum Gravity,” arXiv:1810.05338.
[6] G. Obied, H. Ooguri, L. Spodyneiko, C. Vafa, “De Sitter Space and the Swampland,” arXiv:1806.08362.
[7] H. Ooguri, E. Palti, G. Shiu, and C. Vafa,“Distance and de Sitter conjectures on the Swampland,”Phys. Lett. B788 (2019) 180.

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Khee-Gan Lee
The cosmic web is the characteristic pattern in the large-scale structure of the Universe, caused by the evolution of initial
density fluctuations under the influence of gravity and astrophysical processes over cosmic time. While extensively studied
using galaxy redshift surveys at low redshifts (z < 1), it remains challenging to map the cosmic web at higher redshifts as thegalaxy spectroscopy required to establish 3D galaxy positions becomes expensive.
At IPMU, we have instead exploited the hydrogen Lyman-alpha forest absorption from z ~ 3 background star-forming galaxies to carry out 3D tomographic mapping of the intergalactic medium (IGM) at high redshifts of z~2. With the COSMOS
Lyman-Alpha Mapping And Tomography Observations (CLAMOTO) spectroscopic survey using the Keck-I telescope, wehave established the observational proof-of-concept over a small footprint (~0.2 sq deg) within the COSMOS field, andmade pioneering observations of z ~ 2 galaxy protoclusters and cosmic voids.
In FY2018, we worked to expand the applications of IGM tomography. With visiting JSPS/NSF Scholar Ben Horowitz (Berkeley), we worked on the idea of exploiting the nearly linear nature of the gravitational collapse at z ~ 2 to perform constrained
realization analysis of the cosmic web within an observational volume. Using optimal minimization methods combinedwith a fast approximate N-body simulation code, we developed methods to solve for the pattern of initial density fluctuations which is the best match for the Lyman-alpha forest absorption seen in a given data set. Applied to high-redshift data,
this opens the exciting possibility of predicting the future gravitational evolution of cosmic structures observed at z ~ 2-3.
This will allow us to associate galaxies observed within said structures with their future environments at z ~ 0, thereby making a direct link with galaxy environmental studies from the Local Universe.
Apart from using the Lyman-alpha forest, we are also working towards estimating the density field from galaxy survey data.
While spectroscopic surveys are expensive at z > 1, it is possible to build up sufficient galaxy densities in the COSMOS fieldby combining the multiple spectroscopic surveys that have observed there. Metin Ata (IPMU postdoc) has been working
to carefully correct for the selection functions of the various spectroscopic surveys in order to apply his BIRTH density
reconstruction code, which estimates the underlying density field. With both the density field and Lyman-alpha absorptionin hand, we will then be able to directly test the prevailing paradigm of the large-scale IGM gas as optically-thin photoionized medium.

Research Highlights

5.4 Swampland Conditions

These efforts are paving the way for the future implementation of IGM tomography using the Prime Focus Spectrograph(PFS) on the 8.2m Subaru Telescope in Hawaii. With the Subaru Strategic Proposal (SSP) survey planned to begin in 2022,
PFS will enable 100x larger cosmic volumes to be mapped compared with CLAMATO.

Figure 1: 3D visualization of the reconstructed Lyman-alpha absorption
from the CLAMATO observations shown as a blue haze, covering
2.0 < z < 2.5. For comparison, positions of galaxies with known
spectroscopic redshifts are shown as dots.

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Research Highlights

Mikhail Kapranov
Perverse sheaves were introduced in the early 1980's by Beilinson, Berstein and Deligne [1]. Their goal was to asiomatize thegeometric structure possessed by solutions of holonomic (maximally overdetermined) systems of linear differential equations. This structure is roughly analogous to the familiar concept of a sheaf (local data given for various domains of definition) but does not reduce to a sheaf (hence the attribute “perverse”). Since then, perverse sheaves have found a variety of
applications in algebraic geometry, representation theory and other areas of mathematics.
For several years I was studying perverse sheaves from the point of view of their possible relation to Fukaya categories in
symplectic geometry. The Fukaya category has, as objects, Lagrangian submanifolds of a given symplectic manifold. Itturns out that Lagrangian skeletons, i.e., possible singular Lagrangian subvarieties in a complex Kähler manifold, play animportant role in the classification of perverse sheaves. Namely, a perverse sheaf Ӻ and a Lagrangian skeleton K give rise to
an ordinary (non-perverse) sheaf RK ( Ӻ ) on K, which is a much more transparent object. It can be then analyzed using more
traditional methods and used to describe Ӻ completely.
Working with V. Schechtman [6], I first realized this approach for perverse sheaves smooth with respect to a real arrangennment of hyperplanes in the complex space ℂ . The skeleton K here is the real locus ℝ . Remarkably, already this very simple
setting leads to far-reaching results. Similar results have been obtained for graphs on surfaces [8] and, just recently, forsymmetric product spaces [9], where the classification of perverse sheaves is related to Hopf algebras. This approach also
led to the study, joint with R. Bezrukavnikov, of so-called microlocal sheaves on singular curves, which are systems of perverse sheaves whose moduli spaces possess natural symplectic structures.
These classification results lead V. Schechtman and myself [7] to propose a categorical analog of perverse sheaves which we
called perverse schobers. While a perverse sheaf is, ultimately, a datum of a system of vector spaces, a perverse schober is adatum of a system of categories. Our proposal was to view perverse schobers as “coefficient data” for forming Fukaya categories, just like perverse sheaves can serve as coefficients for taking cohomology. This concept turned out to be useful for
encoding the action fo birational transformations (flops) on the coherent derived categories [3].
Working with M. Kontsevich and Y. Soibelman [5] I related the “algebra of the infrared”of Gaiotto, Moore and Witten [4] withthe concept of secondary polytopes which I introduced (jointly with I. M. Gelfand and A. V. Zelevinsky) in the 1990's todescribe discriminants of polynomials in several variables. It turns out that this construction can also be put in the schober
context: one can speak of the “infrared algebra” in the presense of a shober on the complex plane. More precisely, in theinfrared limit, a supersymmetric theory gives the data of the vacua and of the tunnelling transition between the vacua. In
our interpretation (work in progress with Y. Soibelman and L. Soukhanov) the vacua (or, rather, their central charges) correspond to the singular points of the schober 𝔖. The local category of D-branes corresponding to a vacuum is interpreted as
the category of vanishing cycles of 𝔖. The tunnelling transitions arise as the natural transport functors given by the schober
structure. In this way we get that many features of a physical theory are captured by a perverse schober.
References[1] A. Beilinson, J. Bernstein, P. Deligne. Faisceaux pervers. Astérisque 100 (1983).
[2] R. Bezrukavnikov, M. Kapranov. Microlocal sheaves and quiver varieties. Annales de La Faculté Des Sciences de Toulouse
Math. 25 (2016): 473-516.
[3] A. Bondal, M. Kapranov, V. Schechtman. Perverse schobers and birational geometry. Selecta Math. 24 (2018) 85-143.
[4] D. Gaiotto, G. Moore, E. Witten. Al gebra of the Infrared: String Field Theoretic Structures in Massive N = (2, 2) Field Theory
In Two Dimensions. - arXiv:1506.04087.
[5] M. Kapranov, M. Kontsevich, Y. Soibleman. Algebra of the infrared and secondary polytopes. Adv. in Math. 300 (2016)616-671.
[6] M. Kapranov, V. Schechtman. Perverse sheaves over real hyperplane arrangements. Ann. Math. 183 (2016) 619-679.
[7] M. Kapranov, V. Schechtman. Perverse schobers. arXiv:1411.2772.
[8] M. Kapranov, V. Schechtman. Perverse sheaves and graphs on surfaces. arXiv:1601.01789.
[9] M. Kapranov, V. Schechtman. Shuffle algebras and perverse sheaves. arXiv:1904.09325.

5.7 Closing in on the Ultimate Dark Matter Limits
Forecast by the Fermi Gamma-Ray Space Telescope
Oscar Macias
A myriad of astronomical observations indicate that ordinary matter—the kind of stuff that makes up the stars, planets andus—can only account for about fifteen percent of the total matter of the universe. The remaining fraction is in the form ofa mysterious substance called Dark Matter. Unlike most ordinary matter, it does not appear to emit any form of light that we
could detect with our telescopes—which is how we have learned almost all we know about the universe. It is easy to seethen why it has been so difficult to discover the true nature of this unknown substance.

Research Highlights

5.6 Perverse Sheaves and Their Categorical
Generalizations

Figure 1: The Milky Way Galaxy is embedded in an enormous halo of Dark Matter with the concentration of thisstrange substance peaking at its heart.

One of the leading theories posits that if Dark Matter is made of a special kind of particles, they could collide with eachother and disappear in a glow of gamma ray photons billions of times more energetic than visible light. Although such Dark
Matter annihilations are expected to be incredibly rare in most places in the universe, the odds of detecting this signal canbe greatly increased by aiming our gamma ray telescopes to spots in space with very high concentrations of Dark Matter.
When it comes down to deciding where to find the most intense Dark Matter glow, the heart of our Milky Way Galaxy wins
every time (Figure 1).

Figure 2: L eft: Fermi data from the Galactic Center. Middle: Astrophysical model constructed in Macias et.al. (2019). Right: Fractional residual image (Data-Model)/Model. Our model for this region is so sophisticated that it is almost impossible totell it apart from the actual data. The residual image demonstrates that what remains unexplained in the region isinconsistent with a Dark matter annihilation glow, instead it resembles pure random noise.

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Research Highlights

But as someone once said“extraordinary claims require extraordinary evidence”and in this particular case there was just notenough of the latter. This is in part because the center of the Galaxy is a very violent region filled with uncertain amounts ofinterstellar gas, neutron stars, supernovae remnants and a supermassive black hole—any of which could have been culpritof the excess gamma ray haze. To put an example; a population of rapidly rotating neutron stars (known to generatemagnetic fields about a billion times stronger than that of our Sun) can accelerate charged particles to extreme high energies thereby producing a sea of gamma ray photons as a product of microphysics interactions. The mechanisms at playhere are well understood, the difficulty is that we currently don't know the exact distribution of gas, starlight and stars at theCenter of our Galaxy.
Gradually, as the dust settles, it has become abundantly clear that the Galactic Center excess is not due to Dark matter
annhilations. Using a wide range of information of the sky at different energies along with hydrodynamic simulations,
Macias et.al. (2019) have built up a better model of the astrophysical background for the Galactic Center (Figure 2). This has
allowed us to reconstruct a much sharper image of the gamma-ray signal for more robust analyses and checks. The key
finding of our most recent study is that the excess signal traces stellar populations in the Galactic bulge. The bulge contains
a broad mix of old and newborn stars, which motivates astrophysical gamma ray emitters such as young and millisecond
pulsars as the source of the Galactic Center excess. As a matter of fact, researchers (e.g., Bartels et al. 2018) using complimentary methods have independently confirmed our results.
As shown in Figure 2, we have demonstrated that there remains little Galactic Center excess emission that might be attributed to Dark Matter emission. Our international team is working hard to convert this null detection into some of thestrongest constraints yet on the annihilation rate for Dark Matter particles about a hundred times heavier than a proton.
Some of our preliminary results are very encouraging and suggest that we might be not too far from reaching the ultimate
Dark Matter limits forecast by the Fermi Gamma-Ray Space Telescope (Figure 3).

5.8 Gravitational Waves and Dark Matter
Shi Pi
The first observation of gravitational waves (GWs) from a black hole (BH) merger by the Laser Interferometer Gravitational
Wave Observatory (LIGO) on September 14th, 2015 opened a new window to explore the universe. In the near future there
will be space-based GW detectors like Laser Interferometer Space Antenna (LISA), Taiji and/or Tianqin, DECIGO and BBO.
The targets of these space detectors include mergers of supermassive black holes, extreme mass ratio binary inspirals, andstochastic GW backgrounds. One of the possible origins of stochastic GW backgrounds is primordial; a fossil that preserves
the information from the very early universe. Thus detection of it has a tremendous scientific significance. It gives us clues
to understand the origins of our universe.
The current astronomical and cosmological observations tell us that about 27% of the energy density of our universe is dark
matter, whose origin is a great challenge to modern cosmology and theoretical physics. A possible candidate for dark
matter is primordial black holes (PBHs). PBHs are black holes formed in the very early universe from rare peaks of the primordial scalar curvature perturbations which originate from inflation. PBHs may constitute a large portion of or all of the16
dark matter in our current universe. Black holes evaporate gradually by Hawking radiation. PBHs lighter than 10 g have alifetime shorter than the age of the universe, hence they have evaporated completely by now. While the abundance of
22
PBHs heavier than 10 g is highly constrained by microlensing observations. However, there exists no observational con16
22
straint on PBHs in the mass range 10 g<MPBH<10 g. Therefore, PBHs in this range may constitute all the dark matter of theuniverse.
GWs are found to play the key role in testing or constraining the scenario of such small PBHs as dark matter. Since PBHs areformed from large amplitude scalar perturbations, their mean square amplitude is expected to be large enough to produce
appreciable secondary gravitational waves at nonlinear order. Since these GWs are sourced by the scalar perturbations, wecall them the induced GWs. If the abundance of PBHs is large enough to dominate the dark matter component, it may bepossible to detect the induced GWs in the future. A lucky coincidence is that the frequency band of the induced GWs cor17
22
responding to the only possible mass window for PBHs as dark matter, 10 g to 10 g, exactly matches that of LISA/Taiji/-3
Tianqin, i.e. 10 Hz to 0.1 Hz.

Research Highlights

Using data from the Fermi Gamma-Ray Space Telescope, several research teams claimed to have identified an intriguing
gamma ray signal at the center of our Galaxy which seemed to have been the first ever detection of a Dark Matter annihilation. The excitement in the Dark Matter community was palpable, with research articles on the subject being publishedalmost on a weekly basis in the first few years (by ~ 2012−2013) of the discovery claim.

Recently, we (Rong-Gen Cai (ITP, CAS), Misao Sasaki (IPMU) and I) made a detailed study of the induced GWs from scalar
perturbations. We found that if the scalar perturbations are non-Gaussian, there appears a characteristic multi-peak structure in the induced GW spectrum, which can be used as a smoking gun of non-Gaussianity on small scales. We also foundthat the GW spectrum is large enough to be detected by LISA/Taiji/Tianqin if PBHs dominate dark matter, no matter how
large the non-Gaussianity is. The point is that the GW spectrum is completely determined by the non-Gaussian part of thescalar spectrum in the large non-Gaussian limit. Hence, the existence of large peaks of the scalar perturbations that turn into
PBHs guarantees a non-negligible amplitude of the scalar perturbation power spectrum independent of whether they are
Gaussian or non-Gaussian, which in turn induces detectable stochastic GWs. See the Figure in the case of LISA. The nonGaussianity is characterized by the parameter F NL with the curvature perturbation R being assumed in the form,
R = Rg + FNL Rg2.
Figure 3: S ource: This figure is from Charles et.al. (2016)—for the Fermi collaboration—reproduced with permission of Physics Reports (Elsevier). The Dark Matter annihilation rateversus Dark Matter mass in Giga-electron-Volts units. Projected limits for 15 years of
Fermi data from the Galactic Center region. The Dark Matter particles are assumed to
be annihilating into quarks. Different color bands show different levels of backgroundmodel uncertainties.
Further reading: http://go.nature.com/2CVnzBH.

where Rg is the Gaussian variable. It is clear thatthe induced GWs must be detected by LISA if
PBHs are the dark matter. Conversely if such a
GW background is not observed by LISA, it
severely constrains the amount of PBHs in the17
22
mass range, 10 g to 10 g, where it seems there
is no direct way to constrain it.
Reference[1] Rong-Gen Cai, Shi Pi, and Misao Sasaki, Phys.
Rev. Lett. 122, 201101 (2019).
Link: https://journals.aps.org/prl/pdf/10.1103/PhysRevLett.122.201101

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Research Highlights

5.9 A Machine-Learning Application to
Cosmological Structure Formation

5.10 Good Vibrations: Effective Field Theory
Harmonics
Takahiro Nishimichi

Tom Melia

Our research group is conducting a simulation campaign called “Dark Quest”, which aims to build a simulation database
covering a six-dimensional cosmological parameter space to study the structures in the mass scales ranging from galaxies
to clusters of galaxies. Based on the initial set of simulations sampled at 100 points in the parameter space, each of whichcontains about 10 billion mass elements, we have developed a software“Dark Emulator” that learns the response of various
fundamental statistical measures of the simulated dark matter clumps called “halos” to the input cosmological parameters.
It consists of four main ingredients: i) a carefully chosen experimental design that fulfills desirable projection and spacefilling properties, ii) a huge dimensionality reduction of the data vector obtained from each simulation based on theweighted principal component analysis, iii) nonparametric regression based on the Gaussian process, and, iv) rigorous
cross-validation studies based on the split of training/validation sets, again optimized a priori in the process i).
The high accuracy (typically 2 to 3% precision) and the high evaluation speed (about a few seconds per evaluation per target galaxy sample on a modern laptop computer; this compares to ~ 2 days on a supercomputer using about 600 CPU
cores) together with the flexibility in relating the simulated halos to the observed galaxies allow Dark Emulator to be
implemented efficiently into the actual parameter inference pipeline to analyze observed galaxy data for the first time. The
ongoing galaxy imaging survey with Subaru Hyper Suprime-Cam will be analyzed using our Dark Emulator.

...
G-G auto corr.

...

...
G-G lensing...
...

Galaxy-galaxy lensing Galaxy clustering

propagator
H-H corr.
H-M corr.
mass func.

PCA3
...
PCA2

Principal component analysis

Analytic HOD
modeling

100

Halo stats

10

R [Mpc/h]Reference[1] T. Nishimichi, M. Takada, R. Takahashi, K. Osato, M. Shirasaki, T. Oogi, H. Miyatake, M. Oguri, R. Murata, Y. Kobayashi and
N.Yoshida, The Astrophysical Journal, in press (2019), arXiv:1811.09504 [astro-ph.CO]

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A nice solution to the above Monte Carlo-ists’bugbear has a close analogy with the solution to finding good coordinates to222
parameterise a sphere. The constraint x +y +z =1 is similar to the constraint of total momentum conservation in an event;in the case of the sphere we know to switch to spherical coordinates. One should seek the analogous manifold that theparticle momenta must lie upon; it turns out that, by working with spinor helicity momentum variables, it is identified asa Stiefel manifold [1,2], see Fig. 1. How coordinates for this manifold can be used for Monte Carlo generation was
explored in [3].

...
H-G connection

Galaxyparams
...

1

...

PCA4

Lensing proﬁle0.1

Hidden1

0.01

PCA1

1
0.1

...

10

Gaussian process regression...

Cosmology

Hidden213

M = 1014Msolar/h
M = 1015Msolar/h
M = 10 Msolar/h

100

...

DM density∆Σ(R) [h Msolar/pc2]

Baryon density

Cosmology

Hidden3...

DE eq-of-state Spectral index

1000

Why is it so hard to construct an operator basis? The inherent difficulty is in fact familiar to people working with Monte
Carlo event generators, where it takes quite a tangible form. In a Monte Carlo computer program, LHC events are generated, with particles that have momenta that is on-shell, and where the total momentum in the event is conserved. Oncesuch an event is generated, the Monte Carlo-er may wish, for a variety of reasons, to tweak parts of the momenta configuration slightly. However, it is here the difficulty is encountered: adjusting e.g. particle 1’s momentum in the x-direction alone2
2
will cause its invariant mass E -p to go off-shell; even if its energy is also adjusted to compensate, one still finds that the total
momentum in the event is now non-conserved, requiring further tweaking of the other particles in the event.

Build an “emulator” network(~ a few sec / evaluation for a galaxy sample)...

Identify DM clumps / postprocessing(~1 day / run)...

Supercomputer simulation(~10 billion bodies, 2 days / run)

Hidden4

Efficient sampling schemein high dimensions (6D)
(sequential sampling;training/validation split)

The use of effective field theory (EFT) for physics analyses at the Large Hadron Collider, in particular the standard model (SM)
EFT, is now commonplace, and will form an important part of the experiment’s legacy, as well as providing crucial physics
input to future colliders. An operator basis for an EFT encodes the independent physical measurements one can possibly
make. It also organizes them in terms of how large their impact is, with what are called lower mass-dimension operators
typically - but not always – being more important. The construction of EFT operator bases (in particular the SM EFT at
dimension-6, and subsets of the basis at higher dimension) has been demonstrably - with numerous errors in the literature– tricky. The first ATLAS and CMS constraints on SM EFT dimension-8 operators appearing earlier this year further strengthens the case for obtaining a systematic understanding of operator bases.

Research Highlights

The large scale structure of the universe provides us with useful hints for the understanding of the underlying fundamental
theory governing the dynamics of the universe as well as its contents including mysterious dark matter and dark energy.
The standard way to put this idea forward is parameter inference based on forward models. Although N-body simulations,which follow the gravitational dynamics of a large ensemble of mass elements on supercomputers, have long been recognized as one of the most reliable method to forward model the large scale structure, their computational cost hampers
them to be implemented in the parameter inference, where one has to sample typically millions of parameter combinations until a converged estimate is obtained.

The Sphere

The Stiefel Manifold

Fig 1: A sphere is the collection of points obtained by pivoting the vector u about the origin (left). The (2-frame)
Stiefel manifold is the collection of points obtained by pivoting the coordinate frame (u,v) about the origin(right).

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Research Highlights

5.11 A Big Step Forward for LiteBIRD to Provethe Inflationary Universe
Having identified the kinematic manifold upon which physical observables have support, let us return to the question of
how to construct an operator basis, which determines how many independent measurements of physical parameters one
can make. We can again use the above sphere analogy, where spherical harmonics provide a basis for any function that lives
on the sphere. For our case, it is the harmonics of the Stiefel manifold which will form a basis for physical parameter measurements – these harmonics are in one-to-one correspondence with operators in the EFT.
Phrasing things in the above way reveals some interesting underlying representation theory in the problem [1,2]. The Stiefel manifold has a coset description U(N)/U(N-2) (just as a sphere is identified as the coset O(N)/O(N-1)). The action of the
U(N) group plays an important role, through a duality with what has was shown in [4] to be another organizing group action
on EFTs, that of the conformal group. It turns out that the representation theory of the U(N) determines the representation
theory of the conformal group, and vice versa. Such a mathematical duality has been seen in physics before: in optics,
quantum interferometry, and applications of the Laplace and wave equations, to name a few places. Here, it allows for asystematic construction of the “EFT harmonics” [2]. There are also hints that it has manifestations in phenomenology, one
example being the unusual structure of the anomalous dimensions matrix that describes the renormalization group evolution of the SM EFT [5]; these will be the subject of future investigation.
References[1] Henning, Melia, Conformal-helicity duality and the Hilbert space of free CFTs, arxiv:1902.06747.
[2] Henning, Melia, Constructing effective fields theories via their harmonics, Phys. Rev. D 100 016015, arxiv:1902.06754.
[3] Cox, Melia, Independently Parameterised Momenta Variables and Monte Carlo IR Subtraction, JHEP12 (2018) 038, arxiv:1809.09325.
[4] Henning, Lu, Melia, Murayama, 2, 84, 30, 993, 560, 15456, 11962, 261484, …: Higher dimension operators in the SM EFT, JHEP
1708 (2017) 016, arxiv:1512.03433.
[5] Alonso, Jenkins, Manohar, Holomorphy without Supersymmetry in the Standard Model Effective Field Theory, J. Phys. Lett. B(2014) 10 045, arxiv:1409.0868.

The measurement of the cosmic microwave background (CMB) B-mode polarization allows us to probe the smoking gun
of inflation theory. The amplitude of the B-mode polarization, often quoted by the tensor-to-scalar ratio r, has a one-to-one
relationship with the energy scale of inflation. The current best upper limit is δr < 0.06 (95% C.L.), which came fromcombined data analysis of the ESA Planck mission and the ground-based telescope BICEP on Keck. The observations by
Planck ended in 2013, and the analysis efforts are still carried out today. Following the end of the Planck mission, there has
been no new data coming from space-based measurements. Despite ongoing effort to probe inflationary B-modes fromthe ground and from balloons, the community has been searching for the path for the next-generation CMB polarization
satellite to follow Planck.
Measuring the CMB polarization from space is a particularly attractive avenue for probing the inflation paradigm. This isbecause the inflationary B-mode signal is expected to appear at large angular scales, 2 ≤ℓ≤ 200, which can be accessibleby the full sky survey in a satellite platform. Furthermore, after the Planck and BICEP experiences, the community has
identified the great importance of component separation between the CMB polarization and polarized emissions from the
Galaxy. For this reason, broadband observation is crucial in order to separate the components using the differences
between their spectral shapes. The observational bands of space-borne missions are not limited by the atmosphere, as is
the case for ground or balloon missions. For these reasons, there have been a number of proposals for a next-generation
CMB satellite, yet none had been approved until recently.
LiteBIRD (Fig. 1) is a next-generation CMB polarization satellite that is dedicated to probing inflationary B-modes. The science goal of LiteBIRD is to measure the tensor-to-scalar ratio with the sensitivity of δr = 0.001 for r = 0, or 5σ for each bumpfor r ≥ 0.1. In this way, we test the major large-single-field slow-roll inflation models. The concept of LiteBIRD emerged in2008 as a small satellite to focus on probing the inflationary B-mode signal from space. The LiteBIRD working group wasestablished under the Steering Committee for Space Science. Since then, the LiteBIRD team has undertaken over ten yearsof the groundbreaking effort in the concept design, key technology demonstrations, and developing the team into a serious international collaborative effort. The importance of the science has been recognized, and LiteBIRD's activity has been
supported by the Japanese scientific community including radio astronomy and high energy physics. Kavli IPMU has
played an important role from these early days. The proposal to the Master Plan was submitted from Kavli IPMU, and it was
selected as one of the important large projects in Master Plan 2014 by the Science Council of Japan. Over the last two years,
the team underwent the ISAS/JAXA pre-phaseA to solidify the concept demonstration. After the successful reviews at theend of pre-phaseA2, ISAS/JAXA selected LiteBIRD as the second large-class mission in June 2019. This decision is also
reported to the space policy committee in the Cabinet office.

Figure 1: The artist image of LiteBIRD.

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Kavli IPMU Annual Report 2018

Research Highlights

Tomotake Matsumura(Figure courtesy of ISAS/JAXA.©)

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Research Highlights

5.12 Medical Applications of Gamma-ray
Imaging
LiteBIRD is now the only space-agency selected satellite mission aiming for CMB B-mode measurements in the world(Fig. 2). The overview of the LiteBIRD mission is as follows: The prospective launch year is the 2027 Japanese fiscal year. The
full-sky survey will be carried out for three years from the second Sun-Earth Lagrange point. LiteBIRD contains three telescopes − low, mid, and high frequency telescopes, covering from 34 to 448 GHz with 15 bands. The international partnership has evolved in recent years. The US team is in charge of the transition edge sensor bolometer focal plane unit, and theCanadian team is responsible for the warm electronics. Multiple European nations (France, Germany, Ireland, Italy, Netherlands, Norway, Spain, Sweden, UK) are in charge of the mid and high frequency telescope unit, as well as the sub-Kelvincooler. The detailed responsibility breakdown will be addressed in the forthcoming phase.
In Japan, ISAS/JAXA is responsible for the low frequency telescope antenna, the cryogenic system, and the satellite system.
KEK is in charge of the integration and the ground calibration. Kavli IPMU is responsible for the development and deliveryof the polarization modulator (Fig. 3), which is one of the key instruments to reduce inevitable excess low frequency noiseand systematics of the telescope. Kavli IPMU is also in charge of leading the data analysis.

Figure 2: H
 anding over "THE" torch from Planck HFI PI Jean-Loup
Puget to LiteBIRD PI Masashi Hazumi at the ISAS/JAXA
LiteBIRD Kickoff symposium on July 1 and 2.
(Photograph courtesy of Ms. Tada from IPNS/KEK.)

Figure 3: The breadboard model of the polarization modulator
developed by the Kavli IPMU LiteBIRD team during the
pre-phaseA2.

The team plans to go through PhaseA1 during a timescale of two to three years. This is particularly critical phase. The purpose of this phase is to turn the dream of scientists into a real-world space telescope in a collaborative effort between cosmologists, engineers, and the space industry. This team of scientists and engineers must work in tandem to converge theambitious science goals with cutting-edge engineering and technologies. The LiteBIRD team at Kavli IPMU will continue tolead the development of the polarization modulator unit. We will also undertake knowledge transfer from the concept
demonstration stage in lab-B at Kavli IPMU to the production of the demonstration model with the space industrial partnercompany. Whilst some of the activities will shift toward the space industry, the scientists at Kavli IPMU will be busy on anumber of related activities. We will also prepare for the final performance characterization of the polarization modulator,
for which only scientists can be responsible. This requires testing of the polarization modulator with a superconducting
detector system. We must also evaluate the effects of the space environment on the polarization modulator, such as
interactions with cosmic radiation. Furthermore, we need to plan for the calibration of the polarization modulator. In parallel, we will accelerate the effort to make a bridge between the science goal and the hardware using simulations.
Overall, the news of LiteBIRD's selection as the ISAS/JAXA strategic large class mission is a big step forward for the LiteBIRD
team as well as the cosmology community as a whole. At the same time, this is an opportunity to confront a number ofchallenges in order to make LiteBIRD happen. Please look forward for further progress in our endeavor of inflation searchfrom LiteBIRD and the Kavli IPMU team!

In November 2017, a new collaboration was formed between KavliIPMU, JAXA’s ISAS and Institute for Advanced Medical Research at Keio
University, with a project titled “Hard X-ray and Gamma-ray Imaging”.
Based at Kavli-IPMU, a number of interdisciplinary activities centeredaround the development of advanced hard X-ray and gamma-ray
detectors that can overcome longstanding obstacles faced by researchers at the cutting-edge of nuclear medicine were initiated. Since 2018,
we have also started a research program under the Grant-in-Aid for
Scientific Research on Innovative Areas, titled “Toward new frontiers:
Encounter and synergy of state-of-the-art astronomical detectors andexotic quantum beams”, which will broaden the scope of our experimental activities. To carry out these programs at Kavli IPMU, we havebrought together researchers from the field of physics, engineering, Fig 1: Photo of experiments at EPOC
medicine and pharmaceutical sciences. (Fig. 1).
In vivo and three-dimensional gamma-ray imaging, by means of a probe that includes a small amount of radioactive material that emits gamma-rays, plays a key role in providing improved and novel methods for the diagnosis and treatment ofcancer in the pre-clinical phase. It enables us to visualize and measure cell activity and biological process.
In 2018, we succeeded in establishing a joint research agreement with a group at the Exploratory Oncology Research andClinical Trial Center (EPOC) at the National Cancer Center. Since then, we have performed various experiments by using ourequipment and instruments installed at EPOC. By combining a multi-pinhole collimator with 200-μm diameter pinholes
and a 250-μm pitch Cadmium Telluride (CdTe) double sided detector, we have successfully demonstrated that the system
has sufficiently high energy resolution of 1-2 keV (FWHM) to distinguish between different radionuclides in 10-150 keVenergy range; where present SPECT (Single Photon Emission Computed Tomography) systems based on scintillators find it
difficult to distinguish these radionuclides.
With these improved SPECT performances, it will become possible to simultaneously measure and distinguish the distribution of multiple cancer-seeking molecules (tracers), each labeled with different radionuclides, that emits gamma-rays at
unique energies. Currently, we are carrying out in vivo imaging experiments of small mouse tissues visualized by three
tracers labeled by different radionuclides.
211
Additionally, we have performed experiments using one very promising radionuclide, At, which is being used as a newalpha-ray cancer therapy and for cancer diagnostics. The monitoring of the movement of drugs in the human body and its
distribution in tissue are of particular importance, and the development of an imaging system that can image hard X-rays
211
211
emitted from At sources is required. We have demonstrated that for small At droplets captured in a phantom areclearly resolvable by our prototype system down to a spatial separation of about 200-μm with a good spectral resolution(Fig. 2).

Research Highlights

Tadayuki Takahashi

Fig 2: 211At spectrum and image taken with the CdTe imager

38

Kavli IPMU Annual Report 2018

Kavli IPMU Annual Report 201839

6AwardsAwardsHirosi Ooguri Awarded the 2018 Hamburg Prize for Theoretical Physics

Hitoshi Murayama Named University Professor

On May 24, 2018, it was announced that Hirosi Ooguri, Director of the California Institute of Technology’s Walter
Burke Institute for Theoretical Physics and Kavli IPMU Principal Investigator, has been awarded the 2018 Hamburg
Prize for Theoretical Physics. This prize is awarded by the Joachim Herz Stiftung in partnership with the University of
Hamburg and Deutsches Elektronen-Synchrotron (DESY). This is the first year the prize covers all areas of theoreticalphysics (previously it was given to theorists in quantum information, quantum optics, and quantum many-bodysystems). With a new endowment established for the prize, the prize money has been increased from 40,000 euros
to 100,000 euros, making it one of the most valuable science prizes in Germany. The award ceremony will be held on
November 7, 2018 at Planetarium Hamburg.

On March 27, 2019, the University of Tokyo announced that Kavli IPMU Principal Investigator Hitoshi Murayama had
been given the new title of University Professor. The university established this new title to recognize important
individuals within the institution who are making significant contributions to his or her academic field internationally, and who are continuing to lead research activities that will contribute to further developments in their field in
the future. Murayama is one of four academics to be given this title, which took effect from April 1.

American Physical Society’s 2019 Hans A. Bethe Prize Goes to Ken’ichi Nomoto
Ken’ichi Nomoto, a Kavli IPMU Senior Scientist, has been awarded the 2019 Hans A. Bethe Prize, which wasannounced by the American Physical Society on October 23, 2018. This award recognizes outstanding work in theory, experiment, or observation in the areas of astrophysics, nuclear physics, nuclear astrophysics, or closely related
fields. The prize, consisting of $10,000 and a certificate, is presented annually.
The 2019 Selection Committee awarded Professor Nomoto with this year’s award for his “lasting contributions to ourunderstanding of the nuclear astrophysics of the universe, including stellar evolution, the synthesis of new elements, the theory of core-collapse and thermonuclear supernovae, and gamma-ray bursts.” An award ceremony will
be held during the American Physical Society April 2019 Meeting in Denver, Colorado.

Masami Ouchi Awarded 15th JSPS Prize and Japan Academy Medal
Masami Ouchi, University of Tokyo Institute for Cosmic Ray Research Associate Professor and Kavli IPMU Scientist,
was awarded the 15th JSPS (Japan Society for the Promotion of Science) Award and the 15th Japan Academy
Medal in recognition of his work “Observational Studies of the Early Universe with Ly α Emitters.” An award ceremony
was held at The Japan Academy on February 7, 2019.
The JSPS Prize recognizes young researchers with fresh ideas, who have the potential to become world leaders intheir field. The purpose of the Japan Academy Medal is to honor outstanding young researchers. Up to six awardees(6 researchers this year) are selected every year from among the annual winners of the JSPS Prize (25 researchers thisyear).

For their efforts in helping new international researchers and visitors navigate their way to the Kavli IPMU on their own, a team of Kavli IPMU
administrative staff led by Project Specialist Rieko Tamura has been recognized by this year’s University of Tokyo Business Transformation
Awards. These awards are given out every year to recognize administrative staff and individual departments that have made a significant
contribution to reforming the university.
Tamura’s team received this year’s Special Prize for their work in developing and running a smartphone app, which provides step by step
information in English about how to take public transport from the international airport, how to find and take the free shuttle bus to Kashiwa
campus from the train station, and maps that show where individual researchers’ offices are. It also serves all existing researchers at Kavli IPMU
by becoming an information hub on seminars of the day, who was visiting that day, and where to find certain administrative staff members.
An awards ceremony was held at the Yasuda Auditorium on the University of Tokyo’s Hongo campus on December 19, 2018. Nine groups
including the Kavli IPMU team were commended by the University of Tokyo President Makoto Gonokami or by Executive Vice President
Tomoka Satomi.

AwardsKavli IPMU Staff Commended at 2018 Business Transformation Awards for Their Smart Tech

Masamune Oguri Awarded This Year’s Hayashi Chushiro Prize
Masamune Oguri, the University of Tokyo Research Center for the Early Universe Assistant Professor and Kavli IPMU
Associate Scientist, has been awarded the fiscal year 2018 Hayashi Chushiro Prize.
The prize recognizes researchers who have made significant contributions to planetary science, astronomy, or astrophysics, and has been awarded since 1996 by the Astronomical Society of Japan. The prize itself was made to commemorate the lifetime achievements of outstanding Japanese theoretical astrophysicist Chushiro Hayashi.
Oguri has been recognized for his contribution to the fundamental understanding of gravitational lensing inastronomy. He has for a long time studied gravitational lensing from a theoretical and observational point-of-view,which has provided valuable insight into studies in cosmology and astronomy.

40

Kavli IPMU Annual Report 2018

Kavli IPMU Annual Report 201841

Invited talks given by the Kavli IPMU researchers (Selected 10 of 171)

Conference title

Attendees(from abroad)Date

2-6 April 2018, Lecture hall

47
(21)

May 12, 2018

Hirosi Ooguri

How to Quantize Gravity

Feynman Centennial Symposium

RISTEX Symposium "An analysis of the factors that influence women and girls to pursue
physics and mathematics"

47(0)Jun. 11, 2018

Gabi Zafrir

D-type Conformal Matter and SU/USp
Quivers

VIII Workshop on Geometric
Correspondences of Gauge Theories
International Conference of HighEnergy Physics (ICHEP 2018)

Date, Place

Focus Week on Quantum Gravity and Holography

17 June 2018, Lecture hallPresenter

Presentation title

Conference name

New Directions for LHC - Run 2 and Beyond

52(2)Vertex algebras, factorization algebras and applications

Jul. 4, 2018

Serguey Petcov

14-21 July 2018, Lecture hall

47
(18)

Neutrino Theory(Including Leptogenesis)

RISTEX Workshop "An analysis of the factors that influence women and girls to pursue
physics and mathematics"

10(0)Aug. 5, 2018

Masahiro Takada

Cosmology with Subaru Hyper Suprime- Recontres du Vietnam "Windows on the
Cam imaging survey
Universe"

Aug. 18, 2018

Hiraku Nakajima

3d N=4 QFT and ring objects on theaffine Grassmannian

String-Math 2018

Aug. 27, 2018

Shigeki Matsumoto

Dark Matter Search at 240-250GeV
Lepton Colliders

COSMO 2018

Sep. 14, 2018

Mikhail Kapranov

Perverse schobers and semi-orthogonal
decompositions

Vlkadimir Voevodsky Memorial
Conference

Sep. 15, 2018

Tom Melia

Lovely phase space for good vibrations

PRL 60th anniversary symposiumJan. 25, 2019

Khee-Gan Lee

Lyman-Alpha Forest Tomography:
Mapping the Shadows of the Cosmic
Web at High Noon

JSPS San Francisco Office 15th
Anniversary SymposiumMar. 2, 2019

Hitoshi Murayama

Swampland viewed from bottom up

Accelerating Universe in the Dark

18 June 2018, Lecture hall

10 August 2018, National Graduate Institute for Policy Studies

7th Hyper-Kamiokande Proto-Collaboration Meeting
9-13 September 2018, Lecture hall

80
(73)

IGM2018: Revealing Cosmology and Reionization History with the Intergalactic Medium

110
(74)

Beyond the BSM (The 4th Kavli IPMU -Durham IPPP -KEK -KIAS workshop)

49
(24)

Flavor Physics Workshop 201864
(1)

18-22 September 2018, Lecture hall

1-4 October 2018, Hotel Tenbo, Gunma

30 October - 2 November 2018, Lecture hallNoncommutative deformations and moduli spaces

40
(17)

Stellar Archaeology as a Time Machine to the First Stars

86
(56)

Berkeley Week

38
(14)

19-23 November 2018, Lecture hall
3-7 December 2018, Lecture hall
8-11 January 2019, Lecture hall

8th Hyper-Kamiokande Proto-Collaboration Meeting

102
(53)

Representation theory, gauge theory and integrable systems

72
(21)

Visions for table-top experiments on dark matter

64
(10)

Extremely Big Eyes on the Early Universe

86
(52)

27 January -1 February 2019, Lecture hall
4-8 February 2019, Lecture hall

26-27 February 2019, Lecture hall
25-29 March 2019, Lecture hall

428

Conference Presentations
and Seminar Talks

Kavli IPMU Annual Report 2018

Kavli IPMU Annual Report 2018

Conference Presentations and Seminar Talks

7

Conferences43

9Outreach andPublic Relations

44

DATE

18th Kavli IPMU-ICRR Joint Public Lecture“Exploring Particles, Describing the Universe with Particles”

Apr. 14, 2018

Amuser Kashiwa,
Chiba

333

Kavli IPMU Public Lecture "Universe X World"

Jun. 10, 2018

Miraikan,
Tokyo

215

Kavli IPMU, IRCN joint seminar "Science and Metaphysics"

Jun. 11, 2018

Hongo Campus,
The Univ. of Tokyo

60"Gravitational Waves and the Dark Ingredients of the
Universe"

Jun. 17, 2018

Koshiba Hall,The Univ. of Tokyo

196

Science Cafe 2018 "Universe"

Jul. 8, 2018

Tamarokuto Science Center,
Tokyo

30

Learning and Creating Physics- From High School to theForefront Research of the Universe

Jul. 29, 2018

Hongo Campus,
The Univ. of Tokyo

51

Booth at the 2018 Super Science High School Student Fair

Aug. 8-9, 2018

Kobe International Exhibition
Hall, Hyogo

800

Science Cafe 2018 "Universe"

Sep. 29, 2018

Tamarokuto Science Center,
Tokyo

29

Open Campus Kashiwa 2018

Oct. 26-27, 2018

Kashiwa Campus,
The Univ. of Tokyo

2,905

Kavli IPMU/ICRR joint public lecture - "Particles, Celestial
Events, or the World of Mathematics"

Nov. 11, 2018

Yasuda Auditorium,
The Univ. of Tokyo

282

Actually I Really Love Physics! –Career Paths of Female
Physics Graduates

Nov. 17, 2018

Kavli IPMU

13

Kavli IPMU High School Student Event "Meet the Scientists!"

Dec. 4, 2018

Kashiwa Library,
The Univ. of Tokyo, Chiba34

WPI 7th Science Symposium

Dec. 27, 2018

Toyota Auditorium, Nagoya
Univ., Aichi

820

Kavli IPMU/ELSI/IRCN Joint Public Lecture: "A Question of
Origins"Jan. 20, 2019

Miraikan, Tokyo

226

AAAS 2019 Annual Meeting

Feb. 14-17, 2019

Marriot Wardman Park,
Washington DC, USA

260

Kavli IPMU Annual Report 2018

VENUE

number ofparticipants

TITLE

April 2018–March 20195-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583, Japan

TEL: +81-4-7136-4940

FAX: +81-4-7136-4941 http://www.ipmu.jp/

ISSN 2187-7386

Printed in Japan

Kavli IPMU

Annual Report 2018

Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU)
The University of Tokyo Institutes for Advanced Study
The University of Tokyo