April 2019–March 2020

Kavli IPMUANNUAL REPORT 2019

CONTENTS
FOREWORD

2

1 INTRODUCTION

4

2 NEWS & EVENTS

12

3 ORGANIZATION

14

4 STAFF

18

5 RESEARCH HIGHLIGHTS

24

5.1 T2K Probes Matter-Antimatter Asymmetry in Neutrino Oscillations ���������������������������������������������������������������������������� 24
5.2 New Physics Search Kicked Off at the Electron-Positron Collider Experiment Belle II�������������������������������������������� 26
5.3 Black Hole Microstates and Holography ������������������������������������������������������������������������������������������������������������������������������������ 27
5.4 Primordial Black Holes: Theory Meets Astronomy ���������������������������������������������������������������������������������������������������������������� 28
5.5 Our Origin and Gravitational Wave ������������������������������������������������������������������������������������������������������������������������������������������������ 29
5.6 Anomaly of Electromagnetic Duality of Maxwell Theory Determined ������������������������������������������������������������������������ 31
5.7 Prime Focus Spectrograph (PFS): Subsystems are Coming Together for On-Sky Commissioning ���������������� 32
5.8 The L-function of a CM Elliptic Curve and CFT Correlation Functions �������������������������������������������������������������������������� 34
5.9 An Independent Measurement of H0 from Lensed Quasars �������������������������������������������������������������������������������������������� 35
5.10 HSC-SSP Transient Survey at COSMOS Region �������������������������������������������������������������������������������������������������������������������������� 36
5.11 Parental Gender Attitudes Associated with Japanese Women’s Reduced University Participation �������������� 37

38

7. CONFERENCES

39

8. CONFERENCE PRESENTATIONS AND SEMINAR TALKS

40

9. OUTREACH AND PUBLIC RELATIONS

41

Kavli IPMU

Annual Report 2019
April 2019–March 2020

Copyright © 2019 Kavli IPMU
All rights reserved
Editors: Tomiyoshi Haruyama (Chair), Chiaki Hikage, Misao Sasaki, Junichi Kanzaki
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 2019–March 2020

Kavli IPMUANNUAL REPORT 2019

Printed in JapanOn the cover:
The PFS first spectrograph module under integration inside the dedicated clean roomat the Subaru Telescope observatory on Maunakea. The photograph shows theprocess of mounting one of the two visible cameras on the optical bench (Credit: PFS
project).

Foreword

Foreword

In our astrophysics survey projects, wealth of data coming from the Hyper Suprime-Cam (HSC) at the Subaru
Telescope is providing new insights into our universe. New limits on primordial black holes from HSC data in
Section 5.4, and transient survey at HSC is discussed in Section 5.10. Construction of the Prime Focus Spectrograph (PFS) is in progress, as reported in Section 5.7.
Construction of Hyper-Kamiokande started in April, 2019. The Super-Kamiokande Gadolinium Project is onschedule, and we expect the first detection of diffuse neutrino background detection in a few years. Section
5.1 discusses progress in the T2K experiment.
In CMB experiments, we are excited that ISAS/JAXA approved the launch of the LiteBIRD satellite to test thecosmic inflation.
Belle II experiment has started and is opening a new window to physics beyond the Standard Model of Particle Physics, as described in Section 5.2.
Interdisciplinary research activities are also thriving at the Kavli IPMU, including collaborations between string
theory and condensed matter physics as described in Section 5.6 and between mathematics and string theory as described in Section 5.8.

Hirosi Ooguri
DirectorI

hope this will find you safe and healthy during this difficult time. The COVID-19 pandemic has beenposing challenges to every aspect of operations of our institute. I am grateful to our staff members fortheir dedicated services and for their support to our scientists. They have done exceptional work under
the circumstance where none of them were trained for. This annual report covers the period from April 2019
to March 2020, which ended at the time when the pandemic started to impact our operations seriously. We
will report on our activities in the time of the pandemic in our annual report next year.

In my inaugural address as the Director of the Kavli IPMU in October 2018, I stated my commitment to provide
an inclusive and supportive environment to the diverse group of people in our community. To realize our
mission – solving the most fundamental questions about our Universe – it is essential that all of us treat eachother with respect, maintain our professional working environment free of harassment, challenge our preconceptions, and educate ourselves on our own biases, so that everyone can bring out the best in themselves.
Since then, I have introduced several initiatives to improve our diversity at the Kavli IPMU. We are also conducting scientific research on gender gap at STEM programs, as described in Section 5.11.
Writing this preface reminded me of the wonderful days when our building was bustling with scientists andadministrative staffs working together to advance fundamental sciences. During the COVID-19 pandemic,
our community has not only persevered, but excelled, and we are learning new ways to communicate andcollaborate. I am certain that we will come out better and stronger.

Kavli IPMU’s long term strategic planning exercise was completed in August 2019 and its recommendations
were reported to me. The planning report identified astrophysics surveys, cosmic microwave background(CMB) experiments, and Kamioka underground experiments as our three priority areas. The report also recommended a couple of new initiatives, which we will explore in coming years. These recommendations will
guide us in the coming years, when we make a transition from an institute with a fixed-term funding from the
WPI program to a permanent institute with stable funding.

2

Kavli IPMU Annual Report 2019

Kavli IPMU Annual Report 20193

1

Introduction

F

Y2019 is the third 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 our effort 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
Hyper Suprime-Cam (HSC) survey. In 2019, they
released a catalog of 1800 supernovae detected by the
first HSC transient survey and developed a deep neuralnetwork that automatically classifies the detectedsupernovae into multiple types. Another science project is mass density reconstruction through weak gravitational lensing effect. They have applied a generative
adversarial network to HSC16A data and successfully
reduce the noise. They aim at performing cosmologicalparameter inference using the denoised mass maps.
They have been awarded the highest score A+ in a final
review of the CREST project and will receive further
financial support as a JST AIP program in 2020-2022.
2. Creating new synergies among fields not imaginedat the launch
In vivo and three-dimensional gamma-ray imaging,which enables us to visualize and measure cell activity
and biological processes, provides improved and novel
methods for the diagnosis and treatment of cancer inthe pre-clinical phase. A team led by T. Takahashi performs interdisciplinary activities centered around thedevelopment of an advanced hard X-ray and gammaray detector. In 2019, they have performed various
experiments at the Exploratory Oncology Researchand Clinical Trial Center (EPOC) at the National Cancer
Center. They have established a method to resolve lines
from multiple isotopes using an algorithm developedin X-ray astronomy and thereby individual radiation
doses can be accurately quantified in phantom experi-

4

Kavli IPMU Annual Report 2019

Introduction

INTRODUCTION
ments. They have also performed experiments using avery promising radionuclide, 211At, which is used as a
new alpha-ray cancer therapy and for cancer diagnostics. They have developed a new slat type collimator
made of Tungsten by using 3D printing technology,
which covers a large area of ~10 cm2 with high efficiency.
3. Discovering new major frameworks for geometric
thinking in mathematics and physics with the derived
and noncommutative geometry, such as to unify various types of dualities
Our mathematicians have advanced a new frameworkfor geometric thinking provided by noncommutativeand derived geometry. In particular, Y. Toda usedderived moduli spaces to refine the Donaldson-Thomas invariants to certain monoidal categories, thus categorifying several important duality (wall-crossing)phenomena. His work uses earlier work of F. Sala and M.
Porta on Cohomological Hall algebras (COHAs) whichhave become an important tool in the study of wallcrossing. W. Donovan, with M. Wemyss, used noncommutative deformations to describe the derived monodromy on the stringy Kahler moduli space of a flopping
curve in a 3-fold. M. Kapranov, with V. Schechtman,
related shuffle algebras, appearing in many descriptions of COHAs and wall-crossing, with the GoreskyMacPherson procedure of intersection cohomology
extensions of local systems.
4. Executing projects successfully to produce worldcompetitive results on dark energy, dark matter, andinflation• The HSC team explored how cosmic large-scale
structures evolve as a function of cosmic time using
the first two years data and determined the parameter characterizing the clumpiness of the Universe
today with the world’s highest-level precision. The
Prime Focus Spectrograph (PFS) team achieved
important milestones for the project including a successful engineering trial of the metrology camera

and re-assembling the first spectrograph modules
shipped to Hawaii Observatory.
• The Kavli IPMU is directly involved in the analysis ofT2K data with M. Hartz serving as co-Analysis Coordinator and our former project researcher B. Quilain as
the leader of the Japanese oscillation analysis effort.
T2K for the first time measured the phase that governs CP violation with enough significance and theresult has been published in Nature Journal.
• Cosmic microwave background (CMB) experiments
have been actively led by the Kavli IPMU team.
POLARBEAR team released the science papers
including the measurement of the large angularscale B-mode to aim the signal band of the primordial B-mode. LiteBIRD has been selected as the JAXA/ISAS large class second strategic satellite project andthe team accelerates the design study.
• Belle II has finally launched a decade-long operationof collecting e+-e– collision data using the siliconvertex detector produced in the Kavli IPMU. The firstphysics paper about searches for a new gauge boson
Z' has been accepted for publication in PhysicalReview Letters.
• EGADS team led by M. Vagins finished preparationsof the Super-Kamiokande detector for the additionof gadolinium (Gd), which is expected to start in April
2020.
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. The total number of Principal Investigators (PIs) is 28, among which the number of on-site
PIs are 11. All of our 28 PIs (7 non-Japanese: 25%) areworld-leading scientists and ensure an international
environment for research activities at the Kavli IPMU. H.
Ooguri was conferred the 2019 Medal of Honor with
Purple Ribbon, which is one of the most prestigious
awards in Japan, by the Emperor of Japan for his contribution to the theory of elementary particles. This is anhonor following the 2018 Hamburg Prize for Theoreti-

cal Physics, which was the first year the prize covered allareas of theoretical physics. H. Murayama has been
appointed as a University Professor of UTokyo and also
Hamamatsu Professor from FY 2019. T. Takahashi is aleading astro-particle physicist working in the H.E.S.S.
collaboration, which for the first time detected a gamma-ray burst in very-high-energy gamma light andalso identified very high-energy gamma ray region in
Crab Nebula in 2019. He has been developing hard
X-ray and gamma ray detectors in satellite and rocket
experiments and started a new collaboration with
JAXA/ISAS and Keio University School of Medicine toapply these detectors to biomedical research. The collaboration completed a successful clinical trial using a
newly-developed imaging diagnosis device. On-site
PIs in mathematics, M. Kapranov, Y. Toda, and H. Nakajima, are distinguished mathematicians and conduct
research as leaders in mathematical studies in algebraic
variety, derived category, and gauge theories. M. Vagins
has led the EGADS project, and the refurbishment workof the SK detector was successfully completed in January 2019, to apply the concept (SK-Gd). The SK resumed
data taking with pure water, and is expecting to collectthe world’s first diffuse supernova neutrinos before
2020. M. Takada is the leader of the HSC project, where
fruitful scientific results continue to come out following
the publication of the Publications of the Astronomical
Society of Japan with 40 papers. Other faculty members also play leading roles in each field and include PIsof big international projects such as Belle II, T2K, KamLAND-Zen, PFS, and LiteBIRD.
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
A group of Kavli IPMU administrative staff members
has been awarded the UTokyo’s Special Prize for Business Transformation from the President six times: 2008,2013, 2015, 2016, 2017 and 2018. The 2008 achievement for developing a “website to accept the foreign
researchers in Kashiwa Campus” has already been

Kavli IPMU Annual Report 20195

Introduction

Introduction

requested 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. In 2018,
the Kavli IPMU team developed and manages a smartphone app, which provides step-by-step information
in English about how to take public transport from theinternational airport, how to find and ride the free
shuttle bus to Kashiwa campus from the train station,and maps that show where individual researcher offices are. This has triggered administrative staff in otherdepartments to start developing their own smartphone apps, further advancing system reforms.
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 the University of Oxford are being supervised
by faculty members of the Kavli IPMU, and are being
provided the opportunity to conduct research in collaboration with Kavli IPMU researchers. So far, we haveaccepted eight students and three have defended their
Ph.D. theses. The Kavli IPMU is also working with another international graduate program in physics (GSGC),
which we hope will be extended to astronomy. Youngstudents are becoming attracted to the Kavli IPMU. A
group of UTokyo and Kavli IPMU faculty members,
including Y. Kawahigashi (representative), T. Kohno, A.

6

Kavli IPMU Annual Report 2019

Bondal, M. Kapranov, I. Ueda, and Y. Yamazaki, havebeen 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. One of members visitedthe Hamburg University to discuss the proposal.
8. Enlarging the force for outreach to young students,
by organizing workshops for scientists and high-school
teachers
In FY 2019, the Kavli IPMU kept collaborating with
CoREF (Consortium for Renovating Education of the
Future) to experience the latest advances in scientificresearch for high-school students. An event was carriedout to test the development of an interactive lesson
called “From high school physics to frontier research of
the Universe”, which Kavli IPMU PI H. Murayama andgraduate student Y. Katagiri took part in. On August 5,
2019, high school students were invited to try learning
about the universe. Another activity to stimulate young
female undergraduate and graduate students was carried out under the program“Yes we love Physics-career
path for female students majored Physics” on November 30, 2019. The Kavli IPMU has co-hosted this science
career event together with the Institute for Solid State
Physics and the Institute for Cosmic Ray Research in
UTokyo.
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 funding for thesecond year has been secured. This budget request is
crucial to sustain the Kavli IPMU permanently, and wewill make the request for the final year.
In the following pages, various statistics are shown inplots: the lists of seminars & 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 20197

Introduction

300

273

285

297

300

Total Number of Staff
320
311 318291

RESEARCH ACTIVITIESIntroduction

STAFF

2000

1,689

247

250

230
200

1,449

1500

202

549

1,261 1,245

1,201
158

150

165

100

80
50

194

209

236

245

255

259

252

274

279

642

280
1000

478

125
500

63

21
30
32
29
27
28
29
31
27
25
28
27
22
10
18
0 3
11
10
11
10
10
10
10
10
10
11
11
10
7
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 Mar. 2020
Researchers
Research Support Staffs
Administrative staffs
Total

18
0
3
21

63
10
7
80

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

280
29
11
320

Percentage of Overseas

300

250

44%
52%

200

56%
150

35%
41%
40% 41%

38%
98
79

105

90

0

372
103
269

432
345

60

384

632

555

629

690

711

630

569

510

413

428

1,140

495
807

490
238

938

336

FY 2007 FY 2008 FY 2009 FY 2010 FY 2011 FY 2012 FY 2013 FY 2014 FY 2015 FY 2016 FY 2017 FY 2018 FY 2019
103
269
372

345
87
432

478
384
862

392
238
630

495
336
831

642 549 711
807 1,140 490
1,449 1,689 1,201

569
413
982

510
428
938

184

192

632 555629 690
1,261 1,245

SEMINARS & CONFERENCES
300

41% 49% 42%

250

111

136

118

102

200

105
150

186

100

150

169

163

143

162

147
150
28%
130 131
17
50
94
73
65
46
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 Mar. 2020
517
60
92 100 79 105 98 105 90 102 111 136 118
13
46
65
73
94 130 131 147 150 169 150 163 143 162
28% 28% 48% 56% 52% 38% 44% 40% 41% 35% 41% 41% 49% 42%
0% 2% 5% 6% 5% 2% 5% 5% 6% 4% 6% 8% 9% 10%

Kavli IPMU Annual Report 2019

831

392

87

92

100

8

168
65
103

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

100

48%

Overseas
Domestic% of Overseas% of Female

862

982

50

0

Seminars
Conferences

156

140

4

7

11

24
4

156
7

140
11

196

232

249

246

222

216

207

24
21
18
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 FY 2019
16

186
16

196
12

232
11

249
14

246
13

222
17

184
14

192
11

216
21

207
18

Kavli IPMU Annual Report 20199

Introduction

TOTAL EXPENDITURE
519

500

480
449

450

496

449

90

422

400

68

350

60

57

300

49

250

347

236

350
69

67

75

78

78

81

79

67

252

40
30

115

10

FY 2007 FY 2008 FY 2009 FY 2010 FY 2011 FY 2012 FY 2013 FY 2014 FY 2015 FY 2016 FY 2017 FY 2018 FY 2019
Publications
9
115 202 236 252 347 350 480 449 449 422 519 496% of international collaboration 49% 57% 68% 60% 67% 69% 67% 75% 78% 78% 81% 79%

0

MEDIA COVERAGES AND OUTREACH ACTIVITIES

2,362
1,524

1500 1,366
1000
500
0

1,301

896
25
25
288
132

48
112

911

2,991

1,024
1,259

425
92

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

295
104

1,023

1,006

948

2,864
730

335
119

268
98

494

411

1,310

1,357

408

388
635

3,041
783

846

1,410

2000

1,866

3,262

925

FY 2007 FY 2008 FY 2009 FY 2010 FY 2011 FY 2012 FY 2013 FY 2014 FY 2015 FY 2016 FY 2017 FY 2018 FY 2019
Personnel
Project Activities
Travel Expenses
Equipment
Other Research Project

BREAKDOWN OF FY 2019 TOTAL EXPENDITURE

6,232
6000

1000

933

800

4,545

4,764

5,581

5,454

1,376
135
119
16

163
182

167

541

531
227

366
170

195

551

379
157

316
173

318

1,357
47.3 %

3000

268
9.4 %
98
3.4 %

2000
1000

130
304
222
223
153 137 143 161 203
47
97
143
40 0
27
34
30
29
33
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 FY 2019

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

730
25.5 %

4000

3,339 3,340

400

5000

382

3,277

Kavli IPMU Annual Report 2019

2500

1,225

1,842

3,425

7000

6,084

10

2,707

2,844

2,844

3,902

7,540

7,018

1200

200

3000

20

9

600

3,372

50

50
0

70
60

150
100

3500

80

202

200

(%)
100

(1,000,000 JPY)

3,910

Introduction

PUBLICATIONS

411
14.4 %(1,000,000 JPY)
Personnel
Project Activities
Travel Expenses
Equipment
Other Research Project

Kavli IPMU Annual Report 201911

2News & Events 
July

OctoberJanuaryMay

AugustNovemberFebruary

June

September

December

March>> Hyper-Kamiokande Coordination Meeting>> Quantum Entanglement in Cosmology>> Explosions of universe’s first stars spewed powerfuljets>> Subaru Telescope captures 1800 exploding stars>> 43rd Johns Hopkins Workshop>> 6th Galaxy Evolution Workshop>> Researchers find quantum gravity has no symmetry

Kavli IPMU    Annual Report 2019>> Cryogenics and applied superconducting
technologies to probe the physics of early universe>> Former and current members of Japan’s National
Diet visit Kavli IPMU>> Toward new frontiers : Encounter and synergy ofstate-of-the-art>> Under development medical camera could help cut
time and cost of procedures>> Booth at the 2019 Super Science High SchoolStudent Fair>> AI learns to model our Universe>> 9th Hyper-Kamiokande Proto-Collaboration
Meeting>> 15th exhibition at Kashiwa Library "Beautiful
Mathematics">> WPI Site visit>> Science Cafe "Universe 2019">> The cosmos at high energies: exploring extreme
physics through novel instrumentation>> Parental gender attitudes associated with Japanese
girls’ reduced university participation>> Open Campus Kashiwa 2019>> Open Campus Kashiwa 2019  public lecture: "Who is  
the Man from the 9 Dimensions">> Hirosi Ooguri to receive Medal of Honor from theEmperor of Japan>> Researchers identify very high-energy gamma ray
region in Crab Nebula>> Subaru Telescope 20th Anniversary Conference>> IPMU Annual Report 2018 released>> First detection of gamma-ray burst afterglow invery-high-energy gamma light>> “Actually I Really Love Physics!"–Career Paths ofFemale Physics Graduates>> Focus Week on Primordial Black Holes>> Science and Everyday Life - Series vol.11 Symmetry>> 21st Kavli IPMU/ICRR joint public lecture "The
Forefront of Universe Exploration">> 24th Takagi Lectures>> MEXT Minister Koichi Hagiuda visits Kavli IPMUNews & Events

April 2019-March 2020

April>> Hitoshi Murayama named new Hamamatsu
Professor>> Subaru Telescope helps determine that dark matter
is not made up of tiny primordial black holes>> Prospects of Neutrino Physics>> MEXT Deputy Minister Yoshio Yamawaki visits Kavli
IPMU>> 20th Kavli IPMU/ICRR joint public lecture "Think
about the beginning of the universe"

12News & Events>> Expansion rate of the Universe calculated fromgravitational lensing technique>> 8th WPI Science Symposium "The Power ofMathematics: Bridging Worlds Together">> 14th Kavli Asian Winter School on Strings, Particles
and Cosmology>> East Asia Core Doctoral Forum in Mathematics 2020>> Berkeley Week>> Astrophysics of Gravitational Wave Sources in LIGO/
Virgo Third, Observational Run (O3)>> Integral Geometry, Representation Theory andComplex Analysis>> Researchers find way to show how the tiniest
particles in our Universe saved us from completeannihilation>> Artificial Intelligence tool developed to predict thestructure of the Universe>> Hyper K Proto-collaboration Meeting>> Kavli IPMU/ELSI/IRCN Joint Public Lecture "A
Question of Origins">> Cosmic Acceleration>> Researchers find string theory link in a class ofcomplex numbers>> Successful engineering trial of Metrology Camera at
Subaru Telescope>> Electron-capture supernova: electron-eating neoncauses star collapse

Kavli IPMU    Annual Report 201913

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

Steering Committee

The Kavli IPMU has a rather unique organization. While
research is conducted in a flat-structure 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.

Executive Board
Chair

Hirosi Ooguri
Hiroaki Aihara
Misao Sasaki
Tomiyoshi Haruyama

Director
Deputy Director
Deputy Director
Administrative Director
   /Deputy Director

Mikhail Kapranov
Masahiro Takada
Mark Vagins
Hiromi Yokoyama

Principal Investigator
Principal Investigator
Principal Investigator
Professor

The External Advisory Committee Members (March 2020)
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 2019

Kavli IPMU    Annual Report 201915

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 2019

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
The University of Bonn

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 2019

17

4

Staff

Director
Hirosi Ooguri, Mathematical Physics

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
Stavros Katsanevas, (European Gravitational Observatory),

18

Kavli IPMU    Annual Report 2019

Staff

Faculty Members

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, (Meiji U), 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
Mihoko Nojiri, (KEK), Particle Theory
Yasunori Nomura, (UC Berkeley), Particle Theory
Hirosi Ooguri, (CALTECH), Mathematical Physics
David Spergel, (Princeton U), Cosmology

Tomoyuki Abe, Mathematics
Alexey Bondal, (Steklov Math. Inst.), Mathematics (2019/8/12020/2/15)
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 (till 2019/6/30)
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
Hitoshi Murayama, (UC Berkeley), Particle Theory
Hiraku Nakajima, Mathematics
Yasunori Nomura, (UC Berkeley), Particle Theory (2019/5/188/20)
Hirosi Ooguri, (CALTECH), Mathematical Physics
Tadashi Orita, Experimental Physics
Misao Sasaki, Cosmology
Satoshi Shirai, Particle Theory
John David Silverman, Astronomy
Hajime Sugai, Experimental Physics
Nao Suzuki, Astronomy
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
Naoki Yasuda, Astronomy
Hiromi Yokoyama, Science and Society
Naoki Yoshida, (U Tokyo), Astronomy
Yutaka Yoshida, String Theory

Postdoctoral Researchers
Rodrigo Alonso De Pablo, Particle Theory (till 2019/12/31)
Metin Ata, Cosmology
Neil David Barrie, Particle Theory
Marco Bertolini, Particle Theory (till 2019/8/31)
Tobias Binder, Theoretical Physics
Yalong Cao, Mathematics
Pietro Caradonna, Experimental Physics
Dmitry Chernyak, Experimental Physics (till 2019/6/21)
Peter Jonathan Cox, Particle Theory (till 2019/8/31)
Thomas Rafael Czank, Experimental Physics
Anton Reyes De la Fuente, String Theory (from 2019/9/16)
Zhiyuan Ding, Mathematics (from 2019/9/1)
Matthew Dodelson, String Theory (till 2020/1/31)
Anne Laure Marie Ducou, Cosmology (till 2019/4/30)
Martin Felix Fluder, String Theory (till 2019/8/31)
Dmitrii Galakhov, String Theory (from 2019/9/1)
Shao-Feng Ge, Theoretical Physics (till 2019/9/30)
Ryuichiro Hada, Cosmology
Seyed Morteza Hosseini, String Theory
Chang-Tse Hsieh, Theoretical Physics
Yuko Ikkatai, Science and Society
Jian Jiang, Astronomy
Changwoo Joo, High Energy Physics (till 2019/8/31)
Daisuke Kaneko, High Energy Physics
Miho Katsuragawa, Experimental Physics
Lalitwadee Kawinwanichakij, Astronomy
Ilya Khrykin, Astronomy (from 2019/6/16)
Fabian Koehlinger, Cosmology (till 2019/8/15)
Robin Rinze Kooistra, Astronomy
Naoki Koseki, Mathematics (2019/4/1-9/30)
Tatsuki Kuwagaki, Mathematics
Chiara La Licata, Experimental Physics
Ting-Wen Lan, Astronomy (till 2020/2/29)
Chervin Laporte, Astronomy (from 2020/1/16)
Shing Chi Leung, Astronomy (till 2019/9/30)
Yin Li, Cosmology (2019/4/1-9/29)
Hsueh-Yung Lin, Mathematics (from 2019/9/1)
Wentao Luo, Astronomy
Oscar Macias, Astronomy
Andrew William Macpherson, Mathematics (till 2020/2/29)
Ryu Makiya, Astronomy (till 2019/10/31)
Frederick Takayuki Matsuda, Experimental Physics
Hideaki Matsumura, Experimental Physics (till 2019/6/30)
Tomoko Morii, High Energy Physics
Yuki Moritani, Astronomy
Dinakar Muthiah, Mathematics
Yusuke Nakajima, Mathematics
Keigo Nakamura, Neutrino Physics
Taira Oogi, Astronomy
Shusuke Otabe, Mathematics
Hyunbae Park, Cosmology
Youngsoo Park, Cosmology
Shi Pi, Astronomy
Kavli IPMU    Annual Report 2019

Staff

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

19Anna Puskas, Mathematics (till 2020/1/19)
Benjamin Pascal Jean-Marie Guillaume Quilain, Neutrino
Physics (till 2019/12/31)
Alexis Roquefeuil, Mathematics (from 2019/10/2)
Ipsita Saha, Particle Theory
Yuki Sakurai, Experimental Physics
Francesco Sala, Mathematics (till 2019/11/30)
Yoshiki Sato, Particle Theory (2019/4/1-9/30)
Kallol Sen, Theoretical Physics (till 2019/9/10)
Yota Shamoto, Mathematics
Jingjing Shi, Cosmology (from 2019/11/16)
Yevgeny Stadnik, Theoretical Physics (from 2019/8/1)
David Vincent Stark, Astronomy (till 2019/8/31)
Samantha Lynn Stever, Astronomy
Tomomi Sunayama, Cosmology
Ichiro Takahashi, Astronomy
Satoru Takakura, Astronomy
Po-Yen Tseng, Particle Theory (till 2019/8/31)
Izumi Umeda, Medical Application of Gamma-ray Imaging
Valeri Vardanyan, Cosmology (from 2019/11/2)
Wenting Wang, Astronomy (till 2019/8/31)
Matthias Weissenbacher, String Theory (till 2019/10/15)
John Welliaveetil, Mathematics
Kenneth Christopher Wong, Astronomy
Kiyoto Yabe, Astronomy
Ryo Yamagishi, Mathematics
Gabi Zafrir, Particle Theory (till 2019/10/31)

Joint Appointments
Sergey Blinnikov, (ITEP), Astronomy (2019/9/18-11/7)
Mark Patrick Hartz, (TRIUMF), Neutrino Physics
Masashi Hazumi, (KEK), High Energy Physics
Alexander Kusenko, (UCLA), Particle Theory (2019/10/9-12/8)
Hitoshi Murayama, (UC Berkeley), Particle Theory
Hirosi Ooguri, (CALTECH), Mathematical Physics
Serguey Todorov Petcov, (SISSA), Particle Theory (2019/4/122,9/17-20,11/1-22)
Edwin L Turner, (Princeton U), Astronomy (2019/10/2511/10)
Naoki Yoshida, (U Tokyo), Astronomy

Affiliate Members
Kou Abe, (U Tokyo, ICRR), Astroparticle Physics
Mina Aganagic, (UC Berkeley), String Theory
Shin’ichiro Ando, (U Amsterdam), Astroparticle Physics
Bruce Berger, (LBNL), Neutrino Physics
Melina Bersten, (CONICET), Astronomy
Sergey Blinnikov, (ITEP), Astronomy
Raphael Bousso, (UC Berkeley), Cosmology
Kevin Allen Bundy, (UC Santa Cruz), Astronomy
Andrew Bunker, (U Oxford), Astronomy
Martin Gilles Bureau, (U Oxford), Astronomy
Scott Huai-Lei Carnahan, (U Tsukuba), Mathematics
Cheng-Wei Chiang, (Natl Taiwan U), Particle Theory

20

Kavli IPMU    Annual Report 2019

Yuji Chinone, (U Tokyo), Astronomy
Neal K Dalal, (Perimeter Institute), Astronomy
Patrick Decowski, (U Amsterdam/GRAPPA), Neutrino Physics
Jason Detwiler, (U Washington, Seattle), Neutrino Physics
Mamoru Doi, (U Tokyo, IoA), Astronomy
Chris Done, (Durham U), Astronomy
Yuri Efremenko, (U Tennessee), Neutrino Physics
Motoi Endo, (KEK), Particle Theory
Sanshiro Enomoto, (U Washington, Seattle), Neutrino Physics
Andrea Ferrara, (Scuola Normale Superiore di Pisa),
Astronomy
Gaston Folatelli, (CONICET), Astronomy
Andreu Font-Ribera, (UCL), Cosmology
Brian Fujikawa, (LBL, Berkeley), Neutrino Physics
Kenji Fukaya, (SCGP), Mathematics
Masataka Fukugita, (U Tokyo), Astronomy
Shao-Feng Ge, (Shanghai Jiao Tong U), Theoretical Physics(from 2019/10/1)
Lawrence J Hall, (UC Berkeley), Particle Theory
Koichi Hamaguchi, (U Tokyo), Particle Theory
Jiaxin Han, (Shanghai Jiao Tong U), Astronomy
Tilman Hartwig, (U Tokyo), Astronomy
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
Junji Hisano, (Nagoya U), Particle Theory
Petr Horava, (UC Berkeley), String 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
Motoyasu Ikeda, (U Tokyo, ICRR), High Energy Physics
Shiro Ikeda, (ISM), Mathematics
Yoshiyuki Inoue, (RIKEN), Astronomy
Ken’ichi Izawa, (Tokushima U), Particle Theory
Nicholas Kaiser, (École normale supérieure), Cosmology
Jun Kameda, (U Tokyo, ICRR), Neutrino Physics
Yousuke Kanayama, (RIKEN), Experimental Physics
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, (U Tokyo, ICRR), 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

Kazunori Kohri, (KEK), Cosmology (from 2019/6/20)
Satoshi Kondo, (Middle East Technical U), Mathematics
Yusuke Koshio, (Okayama U), Neutrino Physics
Akito Kusaka, (U Tokyo), Experimental Physics (from2019/6/21)
Alexander Kusenko, (UCLA), Particle Theory
Alexie, Solange Leauthaud Harnett, (UC Santa Cruz),
Astronomy
Shiu-Hang (Herman) Lee, (Kyoto U), Astronomy
Si Li, (Tsinghua U), Mathematical Physics
Marco Limongi, (INAF), Astronomy
Keiichi Maeda, (Kyoto U), Astronomy
Kazuo Makishima, (U Tokyo), High Energy Physics
Brice Menard, (Johns Hopkins U), Astronomy
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
Anupreeta Sadashiv More, (IUCAA), Astronomy
Surhud Shrikant More, (IUCAA), Astronomy
Takeo Moroi, (U Tokyo), Particle Theory
Tomoki Morokuma, (U Tokyo, IoA), Astronomy
David Robert Morrison, (UC Santa Barbara), Mathematics
Shinji Mukohyama, (Kyoto U), Cosmology
Motohico Mulase, (UC Davis), Mathematics
Kentaro Nagamine, (Osaka U), Astronomy
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
Takahiro Nishimichi, (Kyoto U), Cosmology (from2019/10/23)
Ken’ichi Nomoto, (U Tokyo), Astronomy
Hirokazu Odaka, (U Tokyo), High Energy Astrophysics
Hiroshi Ogawa, (Nihon U), Astroparticle Physics (from2019/6/28)
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
Domenico Orlando, (INFN), String Theory (from 2020/1/21)
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
J. Xavier Prochaska, (UC Santa Cruz), Astronomy
Anna Puskas, (U Queensland), Mathematics (from2020/1/20)

Robert Michael Quimby, (San Diego State U), Astronomy
Susanne Reffert, (U Bern), String Theory (from 2020/1/21)
Jason Rhodes, (NASA JPL/Caltech), Cosmology
Joshua Ruderman, (New York U), Particle Theory (from2019/12/13)
Wiphu Rujopakarn, (Chulalongkorn U), Astronomy
Kyoji Saito, (Kyoto U), Mathematics
Ryo Saito, (Yamaguchi U), Astronomy (from 2019/6/18)
Shun Saito, (Missouri U of Sci. and Tech.), Cosmology
Yoshihisa Saito, (Rikkyo U), Mathematics
Yoshio Saito, (U Tokyo, ICRR), High Energy Physics
Hidetaka Sakai, (U Tokyo, Math Sci), Mathematics
Francesco Sala, (U Pisa), Mathematics (from 2020/1/1)
Katsuhiko Sato, (JSPS), Astroparticle Physics
Vadim Schechtman, (U Toulouse III-Paul Sabatier),
Mathematics (from 2020/2/15)
Christian Schnell, (SUNY, Stony Brook), Mathematics
Kate Scholberg, (Duke U), Neutrino Physics
Hiroyuki Sekiya, (U Tokyo, ICRR), Neutrino Physics
Masato Shiozawa, (U Tokyo, ICRR), High Energy Physics
Aurora Simionescu, (SRON Netherlands Inst. for Space
Research), Astronomy
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), Astronomy
Takayuki Tomaru, (NAOJ), Experimental Physics
Nozomu Tominaga, (Konan U), Astronomy
Werner Tornow, (Duke U), Neutrino Physics
Akihiro Tsuchiya, (Nagoya U), Mathematics
Sachiko Tsuruta, (Montana State U), Astronomy
Edwin L Turner, (Princeton U), Astronomy
Kazushi Ueda, (U Tokyo, Math Sci), Mathematics
Hokuto Uehara, (Tokyo Metropolitan U), Mathematics
Mikhail Verbitsky, (HSE, National Research U) Mathematics(till 2020/3/10)
Alexander Voronov, (U Minnesota), Mathematics
Christopher W. Walter, (Duke U), Neutrino Physics
Shin Watanabe, (JAXA), Experimental Physics
Bryan Webber, (U Cambridge), Particle Theory
Roger Alexandre Wendell, (Kyoto U), Neutrino Physics
Marcus Christian Werner, (Duke Kunshan U), Mathematical
Physics
Kavli IPMU    Annual Report 2019

Staff

Staff

21

StaffGraduate Students
Kazuyuki Akitsu, Cosmology
Weiguang Cao, Theoretical Physics (from 2019/9/1)
Laurence Cook, (U Oxford), Neutrino Physics
Henrique De Campos Affonso, Mathematics
Yuichi Enoki, Particle Theory
Kento Furukawa, Experimental Physics
Tommaso Ghigna, (U Oxford), Astroparticle Physics
Alexander Goldsack, (U Oxford), Neutrino Physics
Shunichi Horigome, Particle Theory
Takumi Ichikawa, Particle Theory
Keita Kanno, Particle Theory
Taisuke Katayose, Theoretical Physics
Tenyo Kawamura, Experimental Physics
Tasuki Kinjo, Mathematics
Nozomu Kobayashi, Particle Theory
Yosuke Kobayashi, Cosmology
Asahi Kojima, Particle Theory
Toshiki Kurita, Theoretical Physics
Yasunori Lee, Particle Theory
Xiangchong Li, Cosmology
Tianle Mao, Mathematics
Alexander Nicholas Mason, (U Oxford), Particle Theory (till2019/9/30)
Kairi Mine, Experimental Physics
Yuto Moriwaki, Mathematics (from 2020/1/8)
Kai Murai, Particle Theory
Ryoma Murata, Cosmology
Colm Murphy, (U Oxford), High Energy Physics (from2019/10/1)
Shunsaku Nagasawa, Experimental Physics
Shigenori Nakatsuka, Mathematics (from 2020/1/8)
Mang Chiu Ng, Particle Theory
Tian Qiu, Cosmology
Yotaro Sato, Theoretical Physics
Yusuke Sato, Mathematics
Yuta Sato, Particle Theory
Ryota Shimoda, Theoretical Physics
Yusuke Suetake, String Theory
Sunao Sugiyama, Theoretical Physics
Shenli Tang, Astronomy
Shintaro Toita, Particle Theory
Satoshi Toki, Cosmology
Ryota Tomaru, Experimental Physics
Yutaka Tsuzuki, Experimental Physics
Yota Watanabe, Cosmology (till 2019/4/30)
Yu Watanabe, Particle Theory

22

Kavli IPMU    Annual Report 2019

Xia Xiaokun, Mathematics
Goro Yabu, Experimental Physics
Hiroki Yoneda, Experimental Physics
Chenghan Zha, Mathematics

Berkley satellite Members
Mina Aganagic, (UC Berkeley), String Theory
Raphael Bousso, (UC Berkeley), Cosmology
Lawrence J Hall, (UC Berkeley), Particle Theory
Petr Horava, (UC Berkeley), String Theory
Yasunori Nomura, (UC Berkeley), Particle Theory

Administration

Public Relations

Tomiyoshi Haruyama, Administrative Director, Project
Professor
Yoshihide Sakai, Deputy Administrative Director, Project
Professor
Shinji Kikuchi, General Manager
Akira Takeda, Deputy General Manager

Motoko Kakubayashi
Marina Komori (Project Assistant Professor)
Aya Tsuboi

Accounting
Shigeru Kobayashi*
Naoko Ishida
Hiromi Yoshida
Yukiko Yoshikawa

Kamioka Branch
Fumitoshi Sakai*
Yoshimi Kakioka
Masako Ishikura
Hitoshi Nakagawa(*section head)

Budget Control
Daisuke Hamada*
Madoka Okamoto
Tomoko Shiga
Kaori WatanabeContract & General Purchasing

Staff

Benda Xu, (Tsinghua U, Beijing), Experimental Physics
Masaki Yamashita, (Nagoya U), Astroparticle Physics
Tsutomu Yanagida, (Shanghai Jiao Tong U), Particle Theory
Jun’ichi Yokoyama, (U Tokyo, RESCEU), Cosmology
Masashi Yokoyama, (U Tokyo), High Energy Physics
Shuichiro Yokoyama, (Nagoya U), Cosmology

Kenji Irie*
Yoshiya Ohtaka
Takako Okawa
Sachiko Shimada
Tomoko Yamanaka

General Management
Kazumi Ichimura*
Yuuko Enomoto
Hisami Kuboshima
Mika Miura
Ayako Nakada
Rieko Tamura

International Relations and Researchers Support
Toshiko Furukawa*
Rie Kohama
Eri Kuromoto
Masami Nishikawa
Eri Shinoda
Atsuko Ishizaki

Network and Web Service
Tatsuhiro Yano (till 2020/1/31)
Satoko Inoshita (from 2019/7/1)

PFS Project
Yuki Ishizuka

Planning & Assessment
Shoko Ichikawa

Kavli IPMU    Annual Report 201923

5.1 T2K Probes Matter-Antimatter Asymmetryin Neutrino Oscillations
Mark Hartz

In 1928, Paul Dirac found that the relativistic version of the quantum mechanical wave equation for electrons predicted a
new type of particle with the same mass as electrons but opposition charge. These new particles, called positrons, where
discovered among cosmic rays by Carl D. Anderson in 1932. Since then it has been established through theory and experiment that each particle has a corresponding antiparticle with the same mass but opposite charge and other internal
quantum numbers. The quantum mechanical laws of electromagnetism are symmetric under the interchange of all particles with antiparticles, a transformation called charge conjugation, or C for short. However the weak nuclear interaction
was found to be asymmetric under both the C transformation and the transformation that takes the mirror image of thesystem, called parity or P for short. The symmetry between matter and antimatter, however appeared to be preserved if the
C and P transformations were taken at the same time, called the CP transformation. Even this symmetry fell by the waysidewhen it was discovered in 1964 by Cronin and Fitch that neutral kaons decays are not symmetric under the CP transformation.

Starting operation in 2009, T2K recently published new results with data collected through 2018 with the nearly equal
operation in the neutrino and antineutrino beam configurations. From this data, T2K has extracted a constraint of theparameter δcp. However, the analysis of T2K data is not as simple as checking if the electron neutrino and electron antineutrino event rates are the same or not. While the neutrino beam can be changed between matter and antimatter, the rest of
the T2K experiment, including the earth through which the neutrinos travel and the Super-Kamiokande detector, are madeout of matter. This creates asymmetries in the rates of observed neutrinos and neutrinos, even if there is no CP violation in
the neutrino oscillations. To deal with this, the T2K collaborators must apply a sophisticated analysis that accounts for theseasymmetries that are intrinsic to the experimental apparatus. This analysis is an area where Kavli IPMU researchers haveplayed a key role in both the modeling of the neutrino and antineutrino production, and the fitting procedures to extract
the allowed values of δcp and other parameters that govern neutrino oscillations.
With the collected data and analysis framework, T2K has produced a measurement of δcp that was published in Nature 580(2020) 7803, 339−344. As shown in Fig. 2, T2K prefers a value δcp that is close to −90°, the value at which the neutrino oscillation rate is largest relative to the antineutrino oscillation rate. One CP symmetric value at 0° is disfavored at the 99.7%
confidence level, while the other CP symmetric value at 180° is still allowed. The value at 90°, corresponding to the maximum enhancement of the antineutrino oscillation rate is disfavored at more than the 99.7% confidence level.

Research Highlights

5

Research HighlightS

Research Highlights

The phenomenon of CP violation relates to another mystery in our understanding of the universe. If the Big Bang createdmatter and antimatter in equal parts, why is the universe composed of matter? In 1967 Andrei Sakharov proposed three
conditions to produce an excess of matter in the early universe, and one of these is the presence of CP violation. However,it was ultimately found that the CP violation in the quarks and hadrons, such as the neutral kaons, was not sufficient to
explain the imbalance in our universe. Hence, we look for new sources of CP violation, and one candidates is the phenomenon of oscillations neutrinos.
When neutrinos are produced in one flavor (muon, electron or tau) and transform to another flavor as they propagate overa distance, we call this neutrino oscillations. This processes happens for both neutrinos and their antimatter partners, antineutrinos. The probability to change flavor may be different for neutrinos and antineutrinos, representing a new source ofCP violation. In neutrino oscillations, this potential CP violation is parameterized by a phase δcp. If δcp takes any value otherthan 0° or 180°, CP violation is present in neutrino oscillations.
The Tokai-to-Kamioka (T2K) experiment is a neutrino oscillation experiment in Japan, with a beam of muon neutrinos ormuon antineutrinos generated at the J-PARC accelerator complex that is detected 295 km away in the Super-Kamiokande
detector, as shown in Fig. 1. T2K studies the oscillations of muon neutrinos or antineutrinos to electron neutrinos or antineutrinos and looks for a difference in the oscillation rate between neutrinos and antineutrinos.

Fig. 2: The favored and disfavored values of δcp. The dark gray region is values that are disfavored at a 99.7%
confidence level.

These results represent an exciting hint that there could be significant CP violation in the oscillations of neutrinos. To
definitively establish where CP violation is present, and to measure the magnitude of CP violation will require larger data
sets and the reduction of systematic uncertainties in the analysis of the data. T2K and J-PARC will soon begin upgrades toimprove the T2K near detector and increase the neutrino beam power. Kavli IPMU researchers are participating in these
upgrades through collaboration on the development of a high intensity beam monitor. With these upgrades, T2K will collect more data and refine the measurement of δcp. Beyond T2K, the Hyper-Kamiokande (Hyper-K) experiment has been
approved and has started construction with expected operation in 2027. The centerpiece of the Hyper-K project is a new
detector that will be 8 times larger than Super-Kamiokande, allowing data to be collected that much faster. Kavli IPMU
researchers are excited to be participating in the Hyper-K project with the goal of fully probing the hint of new phenomenathat has been suggested by these T2K results.
Fig. 1: Cross section of the T2K experiment.

24

Kavli IPMU Annual Report 2019

Kavli IPMU Annual Report 201925

Research Highlights

5.2 New Physics Search Kicked Off at theElectron-Positron Collider Experiment Belle II

5.3 Black Hole Microstates and Holography
Seyed Morteza Hosseini

Despite the great success of the Standard Model (SM) of particle physics, the SM is not believed as the Theory of Everything because
several phenomena in the Universe remain unexplained yet by the SM, and thus, the existence of a new physics beyond the SM isstrongly believed. In quest of the new physics, a high-energy collider experiment Belle II was fully started in Japan in March 2019. In+−
Belle II, the properties B, τ, and other particles produced from e - e collisions provided by the SuperKEKB accelerator are measured,and the evidence of the new-physics effect in the measured properties is elucidated by comparing the measured properties with the
SM prediction.
+−

By successfully squeezing the beams at the e - e interaction region, the SuperKEKB had already set the best peak luminosity to
34
−2 −1
−1
1 × 10 cm s , which is the half of the predecessor accelerator’s record. By the end of FY2019, about 20 fb collision data had beencollected.
The performance of the individual Belle II subdetectors was estimated using the cosmic-ray data and e+- e− collision data. The transverse momentum resolution of a charged track with pt = 2 GeV/c was found to be 0.41%, and the kaon detection efficiency and thepion fake rate for a charged kaon with pt = 2 GeV/c were found to be ~0.9 and ~0.1, respectively; they are sufficiently good for theupcoming data analyses. Good integrated performance of the subdetectors was demonstrated by analyzing the neutral B-meson
0
− +
+
−
decay B → D* ℓ ν and its charge conjugate. Two neutral B mesons pair-produced from the e - e collision have the opposite flavor
0–0
until the first B-meson decay at t = t1. After the first decay, the flavor of the second B meson starts to oscillate between B and B due
0 –0
to the B - B mixing mechanism; the oscillation continues until the second B-meson decay at t = t2. Hence, the decay final state of
0 –0
0 –0
0
0
–0 –0
the two B mesons can be one of , (B , B ) , (B , B ) , (B , B ) and (B , B ), where the first two and the second two are denoted by opposite flavor (OF) and same flavor (SF) states, respectively. The flavor of each B meson is determined by the charge information of the
decay lepton. The ratio of the number of the SF events to the SF and OF events was found to be Xd = (17.3 ± 3.6) % [1], which wasconsistent with the previous experiments’ average Xd = (18.58 ± 0.11) %. Finally, excellent vertex-detector performance was demonstrated by measuring the differential ratio of the number of the OF events to the SF and OF events as a function of the second
B-meson flight time Δt ≡ t2 − t1. The Δt was obtained by dividing the displacement of the two B-decay vertices, which are precisely
determined by the vertex detector, by the speed of the B meson. The measured differential ratios are drawn as the black crosses in
Figure 1; they nicely match the Monte Carlo (MC) expectation shown as the blue squares in the same figure.
The first physics paper from the Belle II collaboration was accepted by Physical Review Letters in February 2020 [2]. A new gauge+ −+ −boson Z’ decaying to invisible particles, which can be a dark-sector particle, was searched for in the decay of e e →μ μ Z’ and its+ −±lepton-flavor violating version e e → e μ Z’, where the Z ’ production occurs via radiation off a final state muon, in the collision data
−1of 0.28 fb . The Z’ signature is a peak in the distribution of the invariant mass of the system recoiling against a lepton pair. No significant peak in the recoil-mass spectrum
above the estimated background level was+ −±seen for either μ μ or e μ combinations.
+ −Figure 2 shows the spectrum for the μ μ
Figure 1:
combinations.
The differential ratio of the number of OF events to

There has been a recent progress in understanding black holes’ puzzles, especially deriving the macroscopic entropy of
black holes in asymptotically anti de Sitter (AdS) spacetimes. The Bekenstein-Hawking entropy of a black hole behaves verymuch like a thermodynamic entropy. Though if we really would like to make sense of it as the thermodynamic entropy weneed to ask if it has a microscopic origin à la Maxwell-Boltzmann SBH = kB log dmicro, where kB is the Boltzmann constant anddmicro is the number of black hole microstates.
My research focus in the past five years has been to investigate the quantum properties of black holes in AdS spacetimes
and explain the microscopic origin of their entropy. In my recent works [1, 2], my collaborators and I constructed dyonic
asymptotically AdS5 and AdS7 rotating black strings by uplifting a class of four-dimensional rotating black holes and gave astatistical description of their entropy by using a charged version of the Cardy formula. To this aim, we derived the generalanomaly polynomial for a class of two-dimensional conformal field theories (CFTs) arising as twisted compactifications ofa higher-dimensional theory on compact manifolds, including the contribution of the isometries. This result is then used to
extract the central charges and the levels of the U(1) symmetries in the two-dimensional CFT that are the main ingredientsof the charged Cardy formula.
In [3, 4], a geometric approach (based on certain global, topological data) for computing the central charge of a class of
two-dimensional N = (0, 2) theories obtained by twisted compactifications of D3-brane gauge theories living at a toric Calabi-Yau three-fold has been proposed. In my recent joint work with Alberto Zaffaroni [5], I proved the equivalence of thisconstruction with c-extremization [6] for an arbitrary toric Calabi-Yau. Then, in [7], we investigated the similar problem for aclass of theories obtained by twisted compactifications of M2-branes living at a Calabi-Yau four-fold. The latter is dual
holographically to a class of asymptotically AdS4 × Y7 magnetically charged BPS black holes, where Y7 is a Sasaki-Einsteinseven-manifold. The Bekenstein-Hawking entropy of these black holes can be obtained by extremizing the topologicallytwisted indices of the dual three-dimensional field theories. This principle is known as I-extremization. We showed that theI-extremization procedure is equivalent to its geometric dual for theories without baryonic symmetries and for theories
whose twisted index can be computed in the large N limit, and depends only on three mesonic fluxes.

Research Highlights

Takeo Higuchi

In another step, we provided a unifying entropy functional and an extremization principle for black holes and black strings
75
in AdS4 × S and AdS5 × S with arbitrary rotation and generic electric and magnetic charges [8]. This is achieved by gluing
gravitational blocks, basic building blocks that are directly inspired by the holomorphic blocks appearing in the factorizationof supersymmetric partition functions in three and four dimensions. Generalizations to higher-dimensional black objects
were also discussed in the same paper.

±±

the SF and OF events as a function of the second
B-meson flight time ∆t. The black crosses and blue
squares indicate measurement and MC prediction,
respectively. The data points nicely match the MC
prediction.

Figure 2:
The invariant mass distribution of
the system recoiling against themuon pair. The black points indicate the reconstructed recoil massin the collision data, and the colored region indicates the MC-estimated background level. No significant peak above the backgroundlevel is seen in the distribution.

26

Kavli IPMU Annual Report 2019

The Belle II detector continues with collecting the collision data for the next decade. By
the end of FY2020, it will have collected−1
about 100 fb data. The Belle II collaboration
will keep delivering exciting reports about
various new-physics search results using thevast data samples.
References[1] Y. Yusa, “Time-dependent studies withearly Belle II data”, Proc. of Sci. (Beauty2019) 053 (2020).
[2] I. Adachi et al., Phys. Rev. Lett. 124, 141801(2020).

References[1] S. M. Hosseini, K. Hristov, and A. Zaffaroni, “Microstates of rotating AdS5 strings”, JHEP 11 (2019) 090, arXiv:1909.08000[hep-th].
[2] S. M. Hosseini, K. Hristov, Y. Tachikawa, and A. Zaffaroni, “Anomalies, Black strings and the charged Cardy formula”,
arXiv:2006.08629 [hep-th].
[3] C. Couzens, J. P. Gauntlett, D. Martelli, and J. Sparks, “A geometric dual of c-extremization”, JHEP 01 (2019) 212,
arXiv:1810.11026 [hep-th].
[4] J. P. Gauntlett, D. Martelli, and J. Sparks, “Toric geometry and the dual of c-extremization”, JHEP 01 (2019) 204,
arXiv:1812.05597 [hep-th].
[5] S. M. Hosseini and A. Zaffaroni, “Proving the equivalence of c-extremization and its gravitational dual for all toricquivers”, JHEP 03 (2019) 108, arXiv:1901.05977 [hep-th].
[6] F. Benini and N. Bobev, “Two-dimensional SCFTs from wrapped branes and c-extremization”, JHEP 06 (2013)
005, arXiv:1302.4451 [hep-th].
[7] S. M. Hosseini and A. Zaffaroni, “Geometry of I-extremization and black holes microstates”, JHEP 07 (2019) 174,
arXiv:1904.04269 [hep-th].
[8] S. M. Hosseini, K. Hristov, and A. Zaffaroni, “Gluing gravitational blocks for AdS black holes”, JHEP 12 (2019)
168, arXiv:1909.10550 [hep-th].

Kavli IPMU Annual Report 201927

Research Highlights

5.5 Our Origin and Gravitational Wave

Alexander Kusenko
Kavli IPMU is home to many interdisciplinary projects which benefit from the wide range of expertise available at the institute. One of such projects is the study of primordial black holes (PBHs) from the points of view of fundamental theory,
astrophysics, and astronomical observations. Primordial black holes could account for all or part of dark matter, they could
be responsible for some of the observed gravitational waves signals, they could seed supermassive black holes, and theirinteractions with neutron stars could help synthesis of heavy elements.
The early universe was so dense that any positive density fluctuation of more than 50% would create a black hole. However, cosmological perturbations that seeded galaxies are known to be much smaller. Nevertheless, a number of processes
in the early universe could have created large enough fluctuations. One possibility is that inflation produced large perturbations on small scales. The physics and astrophysical consequences of this process have been studied by the Kavli IPMU
members, including Masahiro Kawasaki, Alexander Kusenko, Misao Sasaki, and Tsutomu Yanagida.
Another possibility, pointed out recently by Kavli IPMU and UCLA researchers, is that a spectator scalar field could develop
an instability leading to large fluctuations and PBHs. Scalar self-interactions can provide an attractive force stronger thangravity. Just as gravitational instability causes hydrogen gas to form stars, the scalar force causes an instability that makes
the scalar field distribution inhomogeneous in the early universe. The lumps of scalar fields can serve as building blocks ofblack holes under some very generic conditions. If the scalar field in question is related to supersymmetry, the masses ofprimordial black holes fall into the range where they can account for all dark matter in the universe.

Hitoshi Murayama
Why do we exist? This is one of the five questions Kavli IPMU is pursuing. Even though the question may sound philosophical, there are clear scientific questions behind it. For example, we need to understand where chemical elements camefrom. We understand that they were synthesized at the core of giant stars and spread out into space after their supernova
explosions. This idea was proven when our friends working on the Kamiokande experiment observed neutrinos comingfrom SN1987A. In 2017, we learned that elements heavier than iron were forged when two neutron stars, cinders after
supernova explosions, merge into a black hole. We are making a great progress!
Unfortunately, this is not enough. For stars to form, we need protons and electrons, both matter particles. But we also knowthat they have anti-matter counterparts. When the Universe started with the Big Bang, the tremendous energy turned into2
matter using Einstein’s famous equation E = m c . But when this happens, matter is created together with anti-matter always
1 : 1. So the Universe must have been filled with a huge number of matter and anti-matter particles of the same number.
When energy can create matter and anti-matter, the opposite can also happen. Matter and anti-matter particles can meetand annihilate into pure energy, again 1 : 1. If so, as the Universe expanded and cooled, every matter particle and antimatter particle must have met and disappeared. The Universe must be empty! But we are here. What happened?

Beginning of Universe

fraction of second later

Universe Now

1

Finally, primordial black holes could form from the “baby universes” created by inflation. A team of Kavli IPMU and UCLA
scientists including Alexander Kusenko, Misao Sasaki, Sunao Sugiyama, Masahiro Takada, Volodymyr Takhistov, and Edoardo Vitagliano have shown that the black holes from the “multiverse” scenario can be searched using the HSC on Subaru,building on the success of the earlier search for PBHs by Masahiro Takada and his team. That search produced not only an
exclusion limit, but also a very intriguing candidate event consistent with a PBH from the“multiverse”. The new observations
have been scheduled on the Subaru telescope to extend the search and to provide a definitive test whether the PBHs fromthe multiverse scenario can explain dark matter.

1,000,000,001

1,000,000,001

1,000,000,002

2

1,000,000,000

usmatteranti-mattermatteranti-matterturned a billionth of anti-matter to mattermatteranti-matter

Research Highlights

5.4 Primordial Black Holes: Theory Meets
Astronomy

we were saved from the complete annihilation!

Figure 1

After the Big Bang created an equal number of matter and anti-matter particles, let us say a billion and one each, somehow
one out of a billion anti-matter particles must have turned into a matter particle (see Fig. 1). Then there is a tiny imbalance
between them, a billion and two versus a billion. When they meet, a billion of them annihilate, but two of them are left over.
Namely, we survived at the expense of a billion friends! The big question is how a tiny amount of anti-matter could turn into
matter. Who is the superhero who saved us from the complete annihilation?
There is a bold theory proposed by two of our emeriti PIs, Masataka Fukugita and Tsutomu Yanagida [1]. They say thesuperhero is neutrinos.

PBH
from
SUSY
PBH from
Multiverse
PBH dark
matter

GW
from
PBH

Figure 228

Kavli IPMU Annual Report 2019

Kavli IPMU Annual Report 201929

Research Highlights

Fukugita and Yanagida went one step further. To give a tiny mass to neutrinos, they hypothesized a clockwise neutrino
nobody has seen. But if it is very very heavy, it makes sense that we haven’t been able to produce it because it requires an2enormous energy (again, E = m c ). This heavy neutrino has no distinction between matter and anti-matter. It is both. For
neutrino to acquire mass, it needs to turn into this clockwise neutrino, but since it is so heavy, it has to turn back to theordinary neutrino very quickly. This is why neutrino can obtain only a tiny mass. But the heavy neutrinos could be produced–26
when the Universe was very very hot, when it was only 10 seconds old. Eventually all decay into ordinary neutrinos oranti-neutrinos. They showed the probability may not be exactly 1 : 1, but a little different. Then voilà! There is a slight difference in the number of matter and anti-matter particles, and we could survive.
How do we know if this is true? One important point is to observe that anti-neutrino can turn into neutrino. We know it is26
very rare, not even once in 10 years. But our PI Kunio Inoue is running a world-leading experiment called KamLAND-ZEN
in this search. Another important point is to find a reason why matter was chosen but not the anti-matter. Namely neutrinos and anti-neutrinos must behave a little differently. Our own Mark Hartz is one of the leaders of the T2K experimentlooking for this subtle difference. They reported just this year that they are 95% certain there is such a difference.
I’ve been asking myself for some time if there could be more evidence we can look for. I discussed this question with ouraffiliate member Kaz Kohri, ICRR postdoc Takashi Hiramatsu, Berkeley postdoc Jeff Dror, and Graham White who was a
postdoc at TRIUMF and is now coming to Kavli IPMU.

5.6 Anomaly of Electromagnetic Dualityof Maxwell Theory Determined
Yuji Tachikawa and Chang-Tse Hsieh
Classical electromagnetism is described by Maxwell's equations, introduced by James Clerk Maxwell almost 150 years
ago [1]. These equations are long known to respect a certain symmetry, called the electromagnetic duality, which exchanges the electric charge and the magnetic charge, as shown in the figure. This duality entails the existence of magnetic
monopoles, hypothetical particles carrying single magnetic poles, which in turn implies that all electric charges in the universe are integer multiples of the minimal charge, as originally found by Paul Dirac in 1931 [2]. This is called the Diracquantization of charges.
It is natural to ask what happens to this electromagnetic duality when considered quantum mechanically. This natural
question, however, has not been studied much, particularly in a situation where there are nontrivial duality actions if we goaround some path in the spacetime. In this work by Chang-Tse Hsieh and Yuji Tachikawa at IPMU and Kazuya Yonekura at
Tohoku University (who is also a former IPMU member), the duality was found to have an anomaly, meaning that it isslightly violated quantum mechanically but in a controllable manner.
Developments in the last several years by condensed-matter physics tells us that the anomaly of a d-dimensional system isbest studied as appearing on the boundary of a (d+1)-dimensional symmetry-protected topological phase of matter.
One famous example is that gapless fermions appear on the surface of topological insulators. In this work, the 3+1 dimensional Maxwell theory was considered as living on the boundary of a hypothetical 4+1 dimensional topological phase ofmatter. In particular, Hsieh had determined the anomaly of 3+1 dimensional fermions from this point of view in his previous
work [3]. In this work, the anomaly of Maxwell theory was found to be 56 times that of a fermion.
The original motivation for this study came from string theory, which requires ten spacetime dimensions with a higher
dimensional analog of Dirac quantization. It was also known that there exist objects in string theory, called orientifolds,
which violate Dirac quantization conditions, potentially rendering string theory inconsistent. A partial resolution of theinconsistency was found by Tachikawa and Yonekura [4] by generalizing previous works by Witten and others, where theanomaly of fermions canceled against the violation of Dirac quantization conditions. There were however still cases where
the inconsistency remained. The present work shows that the consistency in a number of remaining cases can be achievedby incorporating the anomaly of the Maxwell theory.

Figure 3

It has repeatedly happened that an apparent inconsistency in string theory was saved by a subtle and unexpected mechanism; this work can be thought of as another instance of these repeated occurrences. This work might also be of interest tophysicists not particularly interested in string or M-theory, since this work demonstrates that, even after 150 years since theintroduction of the Maxwell equations, there are still so much to be uncovered. This study appeared as [5] and was chosen
as an Editors‘ Suggestion of Physical Review Letters.

We pointed out that this theory could well lead to gravitational waves with nearly scale-invariant spectrum. The reason isthat the clockwise neutrinos are heavy, but not as heavy as they could be: the energy scale of quantum gravity. It suggeststhat the Universe underwent a phase transition, like a normal metal turning into a superconductor, and the clockwise
neutrinos acquired mass because of it. Just like ordinary superconductors, the Universe trapped magnetic field into thintubes called cosmic strings. And cosmic strings are known to reconnect, shrink, and keep emitting gravitational waves.
Future missions can cover practically the entire range of signals (see Fig. 3).
I presented this observation at Kavli IPMU workshop“Prospects of Neutrino Physics”in April 2019 for the first time. Yanagida
was very happy. After making sure all the details work out, we published the paper in the best journal, Physical Review
Letters, and the paper was chosen to Editor’s Suggestion. Now I’m happy, too!
References[1] Masataka Fukugita and Tsutomu Yanagida, Baryogenesis Without Grand Unification, Phys. Lett. B 174, 45-47 (1986).
[2] Jeff A. Dror, Takashi Hiramatsu, Kazunori Kohri, Hitoshi Murayama, and Graham White, Testing the Seesaw Mechanism
and Leptogenesis with Gravitational Waves, Phys. Rev. Lett. 124, 041804 (2020).

30

Kavli IPMU Annual Report 2019

Research Highlights

Every matter particle is spinning, either clockwise or counterclockwise. Experimentally, every neutrino we have seen isspinning counterclockwise. This was OK when we believed that neutrino did not have a mass and always traveled at speedof light. But the Super-Kamiokande experiment, led by our PI Takaaki Kajita, discovered that it has a tiny mass and is nottraveling at speed of light. Then you can in principle go faster and look back at the neutrino (see Fig. 2). It is then moving
backwards, and it is spinning clockwise. Such a particle was not supposed to exist. But we know anti-neutrinos spinclockwise. Is it possible that a neutrino, after you overtake it, becomes an anti-neutrino? Then neutrino can turn matter into
anti-matter and the other way around!

$

N

−

#

Figure 1

+

S

$

#

References[1] J. C. Maxwell, “A dynamical theory of the electromagnetic
field”, https://doi.org/10.1098/rstl.1865.0008[2] P. A. M. Dirac, “Quantised singularities in the electromagnetic field”, https://doi.org/10.1098/rspa.1931.0130[3] C.-T. Hsieh, “Discrete gauge anomalies revisited”, https://
arxiv.org/abs/1808.02881[4] Y. Tachikawa and K. Yonekura, “Why are fractional chargesof orientifolds compatible with Dirac quantization?”,https://doi.org/10.21468/SciPostPhys.7.5.058 https://arxiv.org/abs/1805.02772[5] C.-T. Hsieh, Y. Tachikawa and K. Yonekura, “Anomaly of theElectromagnetic Duality of Maxwell Theory”, https://doi.
org/10.1103/PhysRevLett.123.161601 https://arxiv.org/
abs/1905.08943

Kavli IPMU Annual Report 201931

Research Highlights

5.7 Prime Focus Spectrograph (PFS): Subsystems
are Coming Together for On-Sky Commissioning
Naoyuki Tamura

The instrumentation has been carried out by the international collaboration managed by the PFS Project Office hosted by
Kavli IPMU. The team is actively integrating and testing the hardware and software of the subsystems, and some of them
have been delivered to the Subaru Telescope observatory at the summit of Maunakea in Hawaii. Metrology Camera System(MCS), which was developed at Academia Sinica Institute of Astronomy and Astrophysics (ASIAA) in Taiwan, arrived at
Subaru in 2018, and tests were successfully completed on the telescope through the two nighttime engineering runs, one
in October 2018 and the other in August 2019 with sufficient hardware and software optimizations accommodated(Figure 1). Soon after that, the first spectrograph module with visible cameras was delivered from Laboratoired’Astrophysique de Marseille (LAM) to Subaru in November 2019 and was successfully reintegrated in December (Figure 2).
The performance was confirmed by tests in early 2020, and now data of calibration lamps are continually taken for thecharacterization of the instrument and data stabilities, and for data reduction pipeline development. In parallel to these
activities, the integration and test of the other subsystems and subcomponents are progressing at the sites of PFS partner
institutes (Figure 3) for their deliveries to the Subaru Telescope observatory later in 2020 onwards. The software develop-

Figure 2: The first spectrograph module fully reassembled in the
dedicated clean room in the Subaru telescope enclosure building.

Figure 1: The Metrology Camera System installedat the Cassegrain focus of the Subaru
Telescope.

32

Kavli IPMU Annual Report 2019

Figure 3: Left -- The fiber cable under integration at Laboratório Nacional de Astrofísica
(LNA) in Brazil that will be installed on the telescope and will transmit lightfrom the Prime Focus Instrument on the Subaru prime focus to Spectrograph
System. Right -- The focal plane of Prime Focus Instrument under integration
by ASIAA and their partner ASRD (Aeronautical Systems Research Division)of CSIST (Chung-Shan Institute of Science and Technology) in Taiwan.

ment is also rapidly progressing. The instrument control software is being fleshed out as the subsystem testing progresses,
and in addition, we managed to make good progress in its development at the system level that orchestrates the operations of the subsystems exploiting the MCS engineering runs. The developments of data reduction pipeline and data processing mechanism by Princeton University, National Astronomical Observatory of Japan (NAOJ) and Kavli IPMU are being
accelerated as more data are taken from the spectrograph. The prototyping of science database by NAOJ, Johns Hopkins
University (JHU) and Kavli IPMU is also continuing and now it is being upgraded to Ver. 2.5. The team is aiming to start ontelescope engineering observations from mid 2021, and scientific operation of the PFS instrument from 2023.
As the instrument development is progressing, the collaboration is in parallel trying to develop a timely plan of large-sky
survey observation to be proposed and conducted in the framework of Subaru Strategic Program (SSP). Having the threemain survey components labelled as cosmology, galaxy & AGN evolution, and Galactic archaeology, the team is aiming ataddressing key questions in the modern cosmology and astrophysics by multiple approaches over multiple scales of dark
matter density structure, leading to comprehensive challenges to the LCDM cosmology. The team has been continuously
updating and refining the plan in detail through discussions regularly by remote meetings and e-mails and occasionally bythin-person meetings such as the science meeting in October 2019 at Columbia University, and the 11 general collaboration
meeting in December 2019 at California Institute of Technology (Figure 4).

Research Highlights

We at Kavli IPMU are working on a major astronomical instrument called PFS (Prime Focus Spectrograph), a next generation
facility instrument on the Subaru telescope. It is a very wide-field, massively multiplexed, and optical & near-infrared spectrograph, and Kavli IPMU is the leading institute in both aspects of the instrument development and the planning of a360-night observation campaign on the Subaru telescope for cosmology, galaxy evolution, and galactic archaeology science. Exploiting the Subaru’s prime focus, 2394 reconfigurable fibers will be distributed in the 1.3 degree-diameter field ofview. The spectrograph system has been designed with 3 arms of blue, red, and near-infrared cameras to simultaneously
deliver spectra from 380 nm to 1260 nm in one exposure. From the Subaru’s prime focus, the Hyper Suprime Cam (HSC)
has been continuously delivering superb imaging data over a large area of the sky. Conducting spectroscopic follow-up
using PFS is crucial to complete a large census of the universe. This is unique not only because it exploits the unique capabilities of the Subaru Telescope such as the light-gathering power of the 8.2 m primary mirror, and the wide field of view on
the prime focus, but also because HSC and PFS enable deep imaging and spectroscopic surveys of the same patches of thesky using the same 8.2 m telescope, so one can well understand various systematics in the data which is essential for robust
understandings of statistical properties of the universe.

Figure 4: G roup photo of the 11th PFS general collaboration meeting at California Institute of Technology in Decmeber 2019.

As we are approaching the period of on-sky engineering observations, start of science operation and thus start of the PFS
SSP survey, the interplays between the science team and technical team are more and more crucial, to share not only thebasic performances but also the other detailed characteristics of the instrument, and mutually optimize the software components, data flow, and survey management. The members in Kavli IPMU will be playing key roles not only in the integration and commissioning of the PFS instrument, but also in the coagulation of the entire collaboration during the coming
key phases of the project in the following fiscal years for ultimate scientific and technical success of PFS.

Kavli IPMU Annual Report 201933

Research Highlights

5.8 The L-function of a CM Elliptic Curveand CFT Correlation Functions

5.9 An Independent Measurement of H0 fromLensed Quasars

Taizan Watari and Satoshi Kondo

Kenneth Wong

Think of an algebraic variety X whose defining equation involves polynomials with all the coeﬃcients in some intermediate2
3
field; an example is X : = {(x, y) | y = 4x − g2 x − g3} with g2 , g3 ∈ k for some intermediate field k. The L -function L (X/k, s) isbelieved to encode the information of the number of solutions (x, y) to the polynomial equation in k. An intriguing observation by number theorists more than a half century ago suggests that such L-functions have corresponding modular forms
or automorphic forms. This conjecture has been a subject of intensive study since then; for X as an elliptic curve and k = ℚ,
there is now a proof.
By giving a mathematical proof, one acquires confidence in the validity of a well-defined statement (such as the conjectured one-to-one correspondence between the L-functions of elliptic curves and certain kinds of modular forms). It is yet
another question, however, why there is such a correspondence between seemingly unrelated objects. Incidentally, string
theory probes a geometry (space-time) by translating the geometry into a conformal field theory on Riemann surfaces,
where physical observables often take the form of modular forms. So, a collaboration of Satoshi Kondo (Middle East Technical University, with joint appointment at Kavli IPMU) and Taizan Watari (Kavli IPMU) posed the following question: whether
the modular forms that correspond to the L- functions have something to do with the modular forms that appear as
physical observables in string theory.
Let X be an elliptic curve of Shimura type, where the imaginary quadratic field of complex multiplication is denoted by K,
and the field of moduli of X by k. It is known that the string theory with X(ℂ) as the target space corresponds to a rational
conformal field theory, when the Kähler parameter is chosen appropriately. Within this set-up, Kondo and Watari found that
the L-function L(X/k, s) can be expressed by using the Mellin transform of the following class of chiral correlation functionsof the rational conformal field theory:FIL0
f I1Ω’(τws , β) : = TrR ; V [(−1) Fqws
β

−3/24

ℂ

(∂X )] ;(1)

here, β labels irreducible representations of the chiral algebra of the rational conformal field theory, and τws the complex
structure of a g = 1 Riemann surface (worldsheet); the trace on the right side is over the Ramond sector left-mover vector
2πiτwsspace of states in β (denoted by R; Vβ), F is the Fermion number operator of the N = 2 superconformal algebra, qws : = e , L0ℂ
the Virasoro generator, and ∂X a complex combination of the weight-1 currents of the conformal field theory corresponding to the translation symmetry of the torus X(ℂ). This study revealed that the modular transformation of the g = 1 worldsheet is the origin of the modular property of the functions that correspond to the L-function, so long as this class ofgeometry X and the field of moduli k are concerned. For more information, see S. Kondo and T. Watari, Commun. Math. Phys.
367 (2019) pp.89–126, “String-theory realization of modular forms for elliptic curves with complex multiplication”.

The “flat ΛCDM” model of cosmology has been highly successful at explaining a variety of observations. In particular, it isremarkably consistent with observations of the cosmic microwave background (CMB) taken by the Planck mission [1].
Under the flat ΛCDM model, Planck places a tight constraint on the Hubble constant, the present-day expansion rate of the
Universe, of H0 = 67.4 +/− 0.5 km/s/Mpc. However, observations of type Ia supernovae calibrated by the local Cepheid distance ladder find a higher value of H0 = 74.0 +/− 1.4 km/s/Mpc (SH0ES collaboration; [2]). This 4.4 σ discrepancy between
the CMB and distance ladder measurements, if unresolved, may force the rejection of flat ΛCDM in favor of new physics.
Additional independent measurements of H0 are needed as an important check of systematics.
Strong gravitational lensing, in which the gravity of a massive object (the“lens”) deflects light rays from a background object(the “source”) to create multiple images, can be used to determine H0 through “time-delay cosmography”. The light rays
arriving from different images of the source take slightly different paths through spacetime, and thus arrive at the observerwith a time delay between them. The length of this time delay is directly related to H0. If we can measure the time delay,
accurately model the mass distribution of the lens, and account for perturbers along the line of sight, we can directly calculate H0 independent of the CMB and the distance ladder.
The H0 Lenses in COSMOGRAIL’s Wellspring (H0LiCOW) project [3] has been conducting the most detailed time-delay
cosmography analysis to date. We have precise time delay measurements of several lensed quasars from long-term dedicated monitoring. In addition, we use high-resolution imaging from the Hubble Space Telescope and ground-based adaptive optics, along with spectroscopic observations of the lens galaxies, to perform detailed lens mass modeling. Furthermore, we have obtained wide-field imaging and spectroscopy to characterize line of sight structure. With this large dataset,
we have analyzed six lenses (Figure 1) in our latest milestone result [4]. Our analysis is performed blindly with respect to thecosmological parameters of interest in order to avoid confirmation bias.
From the combination of six lensed quasars, we attain a 2.4% precision measurement of H0 = 73.3 (+1.7/−1.8) km/s/Mpc ina flat ΛCDM cosmology (Figure 2), which is in 3.1 σ tension with the Planck CMB result. We also test simple extensions to flat
ΛCDM such as allowing for spatial curvature, a time-varying dark energy equation of state parameter, and variable neutrino
species and masses, but none of these are able to provide a clear resolution to the tension. Since H0LiCOW and SH0ES arecompletely independent late-Universe probes of H0, we combine them and find a 5.3 σ discrepancy with Planck. This provides further evidence of a tension between early and late-Universe determinations of H0 [5], suggesting the possibility of
new physics beyond flat ΛCDM.

Figure 2: 
H0 posterior PDFs for the individual H0LiCOW lenses (colored curves), as well as the
combined constraint from all
six systems (black line). The
median and 16th and 8th
percentiles are shown in the
figure legend.

Figure 1: Multicolor images of the six gravitationally-lensed quasars analyzed in
the latest H0LiCOW results.

34

Kavli IPMU Annual Report 2019

Research Highlights

In between the field of rational numbers ℚ and the field of complex numbers ℂ, there are infinitely many intermediate
fields. Those intermediate fields form an intricate network under the relation of one of them containing another; this network remains to be a rich subject of research in number theory.

References[1] Planck Collaboration 2018, A&A, in press (arXiv:1807.06209)[2] Riess et al. 2019, ApJ, 876, 85[3] Suyu et al. 2017, MNRAS, 468, 2590
[4] Wong et al. 2020, MNRAS, in press (arXiv:1907.04869)[5] Verde, Treu, & Riess 2019, NatAs, 3, 891
Kavli IPMU Annual Report 201935

Research Highlights

5.10 HSC-SSP Transient Survey at COSMOS Region

5.11 Parental Gender Attitudes Associatedwith Japanese Women’s Reduced University
Participation

Naoki Yasuda
A supernova is the name given to an exploding star that has reached the end of its life. Supernova classified as Type Ia isuseful because its constant maximum brightness allows us to measure its luminosity distance. Using this characteristics, theaccelerated expansion of the Universe has been discovered [1][2] and more distant supernovae are being observed tounderstand the nature of dark energy.
In order to discover supernova effectively and measure the light curve ofthem, we need to monitor wide area of the sky for a long time. High quality and wide field image of Hyper Suprime-Cam (HSC) mounted on the
Subaru telescope with large aperture mirror is the best tool in the world forthis kind of observation.

We used a psychological measure of gender role attitudes called SESRA-S to measure parental attitudes. We used an online
survey to canvas 618 mothers and 618 fathers across Japan with at least one daughter who had graduated from university
and at least one son. We found that while parents’ showing higher scores on gender equality attitudes did not mind what
field of study girls chose, those with lower scores were opposed to girls choosing any field at university [1]. Over 40% of
parents surveyed in this study either “strongly agreed”or “somewhat agreed”with girls’own choice of any university course.
However, in the case of science courses, their main reason for agreement was because of the availability of employment
opportunities after university, while they regarded the humanities as a suitable area of study for girls.

Fig 1. A map showing all of the supernovae (in red)
discovered in this study. The blue circles
indicate the areas HSC was able to capture in
one shot. The background is an image takenby the Sloan Digital Sky Survey. An image ofthe moon has been added to understandthe area of night sky HSC can capture.

By fitting an empirical model of SN Type Ia spectro-photometric time series to multi-color light curves, about 400 supernovae are classified as Type Ia. Among them, spectroscopic redshift or photometric redshift using 30-band photometry
ranging from UV to IR are available for 129 supernovae and the median redshift of this sample is z = 0.97. In particular, 58
supernovae are located at z >1. In comparison, Hubble Space Telescope took about 10 years to discover a total of 50 supernovae located at z >1. This fact demonstrates the very high survey power of Subaru telescope and HSC. For SN Ia beyondz >1.2, the peak flux of SN Ia goes into the infrared (IR) and the error of the color correction to get standardized absolutemagnitude becomes large if we only use optical information. We have conducted an IR imaging follow-up observation via
the HST to reduce the color-associated error for 26 SN Ia candidates.
HSC16aasd (nonIa, z=0.19)

HSC17bigx (Ia, z=1.00)

HSC17bqai (Ia, z=0.38)

HSC16aqﬁ (Ia, z=1.25)

HSC17bjyn (Ia, z=0.63)

HSC17aydg (Ia, z=1.45)

HSC17cbcd (Ia, z=0.87)

HSC16adga (SLSN, z=2.40)

Fig 2. Some supernovae discovered in this study. There arethree images for each supernova for before it exploded(left), after it exploded (middle), and supernovae itself(difference of the first two images).

36

Kavli IPMU Annual Report 2019

In Japan, women’s participation in STEM (Science, Technology, Engineering, and Mathematics) fields remains lower than in
North America and Europe. Japan ranked 110 out of 149 countries on a 2018 gender-gap survey, underscoring Japanesewomen’s limited participation in the economy and government. However, despite multiple government and industry initiatives, encouraging greater participation across society is challenging in a country where gender role divisions are deeply
entrenched. As part of a larger research project looking at why so few women in Japan choose STEM programs at university, we looked at parental influence on girls’ choice of university subject and public perception of several academic fields.

The dataset obtained by our transient survey is useful for the studies of other type of supernova other than SN Ia. There has been
increasing interest in using SN Type II for cosmological applications. The SN II light curves are characterized by a rapid increase
to the peak value (~7 days), followed by a slow decline, frequently
showing a plateau, for ~100 days. Our transient survey is also
suited to SN II discovery and characterization of the entire evolution of their multi-color light curves. We used one SN II to extend
the SN II Hubble diagram to z = 0.340 from z = 0.190 [4]. In addition, we have identified 5 super luminous supernovae at z >2 andan event rate at these redshifts has been measured [5].
References[1] Riess, A. G., et al. 1998, AJ, 116, 1009.
[2] Perlmutter, S., et al. 1999, ApJ, 517, 565.
[3] Yasuda, N. et al. 2019, PASJ, 71, 74.
[4] de Jaeger, T. et al. MNRAS, 472, 4233.
[5] Moriya, T. et al. 2019, ApJS, 241, 16.

Parental agreement with girls’choosing to study in each field. Parents were asked to respond about it in general, rather thanabout their own daughter in particular.
While parents are sensitive to societal changes, some still maintain an image of engineering as not suitable for women,
despite strong demand for female talent across engineering fields. It may be that STEM fields in Japan need to update theirimage. We know that parents with positive attitudes about gender equality can support girls going to university, so it isessential that we improve societal attitudes about gender equality as a whole.
We also investigated whether the public perception of several academic fields was gender- biased in Japan using
SESRA-S [2]. We found that 1) the gender-bias gap in public perceptions was largest in nursing and mechanical engineering, 2) people who had a low level of egalitarian attitudes about gender roles perceived that nursing was suitable forwomen, and 3) people who
had a low level of egalitarian
attitudes perceived that many
STEM fields are suitable formen. This suggests that gender-biased perceptions of academic fields can still be foundin Japan.

Research Highlights

We have conducted a deep transient survey at COSMOS region (7.5 square
degree, 5 pointings of HSC) in Sextant as a part of HSC-SSP from November
2016 to April 2017 with a cadence of 2 epochs per lunation per filter [3].
The limiting magnitudes per epoch are as follows: 26.4, 26.3, 26.0, 25.6,
and 24.6 mag in the g-, r-, i-, z-, and y-band. The dataset obtained is oneof the deepest wide-field transient surveys attempted to date. We haverecorded about 65,000 transients. After excluding objects having light
curves dominated by negative fluxes and objects whose host looks likestars, we have visually checked them and identified about 1,800 supernova (Figure 1 and Figure 2). For the detection of the transients, machinelearning methods are also applied.

Hiromi Yokoyama

We are promoting several other studies, and we would liketo clarify why there are few
women in physics and mathematics, especially in Japan.
References[1] Ikkatai Y.,Inoue A., Kano K., Minamizaki A., McKay E., Yokoyama H.M.,(2019). Parental egalitarian attitudes towards genderroles affect agreement on girls taking STEM fields at university in Japan., International Journal of Science Education 41(16),2254-2270[2] Ikkatai, Y., Minamizaki, A., Kano, K., Inoue, A., McKay, E., & Yokoyama, H. M. (2020). Gender-biased public perception of
STEM fields, focusing on the influence of egalitarian attitudes toward gender roles. Journal of Science Communication,19(1), A08.

Kavli IPMU Annual Report 201937

7

Conferences

Hirosi Ooguri to receive Medal of Honor from the Emperor of JapanThe Emperor of Japan conferred a Medal of Honor with Purple Ribbon to Hirosi Ooguri, Director of the Kavli Institutefor the Physics and Mathematics of the Universe at the University of Tokyo and the Fred Kavli Professor of Theoretical
Physics and Mathematics at the California Institute of Technology.
The awards was conferred by Emperor Naruhito on November 3, 2019, the Culture Day holiday and the birthday ofEmperor Meiji, who established the awards in 1881. Medals with Purple Ribbon were added in 1955 to recognize“individuals who have contributed to academic and artistic discoveries, inventions, and innovations.”

Conference title

Attendees(from abroad)

Date, Place

Prospects of Neutrino Physics

100
(21)

Hyper-Kamiokande Coordination Meeting

58
(15)

Quantum Entanglement in Cosmology

32(8)43rd Johns Hopkins Workshops

53
(10)

6th Galaxy Evolution Workshop
5-7 June 2019, Lecture hall

88
(2)

Cryogenics and applied superconducting technologies to probe the physics of early
universe

52(2)8-12 April 2019, Lecture hall
8-9 May 2019, Lecture hall

21-22 May 2019, Lecture hall

Professor Masaki Oshikawa named new American Physical Society Fellow
Kavli IPMU Senior Scientist Masaki Oshikawa was elected as a 2019 Fellow of the American Physical Society. He wasnominated by the Division of Condensed Matter Physics. The APS Fellowship Program recognizes members who
have made significant contributions to the advancement of physics.
Oshikawa has collaborated with Kavli IPMU researchers.

3-7 June 2019, Lecture hall

3 July 2019, Lecture hall

Toward new frontiers : Encounter and synergy of state-of-the-art

49(0)

9th Hyper-Kamiokande Collaboration Meeting

101
(34)

The cosmos at high energies: exploring extreme physics through novel instrumentation

93
(18)

Subaru Telescope 20th Anniversary Conference

240
(86)

Focus Week on Primordial Black Holes

54
(15)

The 14th Kavli Asian Winter School on Strings, Particles and Cosmology

106
(70)

East Asia Core Doctoral Forum in Mathematics 2020

60
(36)

Berkeley Week

53
(15)

Astrophysics of Gravitational Wave Sources in LIGO/Virgo Third, Observational Run (O3)

45
(31)

Integral Geometry, Representation Theory and Complex Analysis

40(5)

10th Hyper K Proto-collaboration Meeting

95
(53)

Cosmic Acceleration

105
(9)

15-16 July 2019, Lecture hall

Other prestigious awards
Recipient's nameShiro Ikeda (The Event Horizon
Telescope Collaboration)

Name of Award
Einstein Medal

2-6 September 2019, Kashiwa Research Complex
16-18 October 2019, Lecture hall

17-22 November 2019, Waikoloa Beach Marriott Resort & Spa
2-6 December 2019, Lecture hall

Takaaki Kajita

IUPAP-TIFR Homi Bhabha Medal and Prize

13-22 January 2020, Tohoku University
Young-Kee Kim

2019 Scientist of the Year jointly by the Korean Scientists and Engineers Association (US) and the Korean Federation of Science and Technology Societies (Korea)

Yuko Ikkatai

Japan Society for Science Education Best Presentation Award for Young scientist
2019

Keigo Nakamura

High Energy Physics Young Researcher's Award 201914-17 January 2020, Lecture hall

14-17 January 2020, Seminar Room B
20-24 January 2020, Lecture hall
27-28 January 2020, Lecture hall

Keigo Nakamura

Young Scientist Award of the Physical Society of Japan, 2020

5-9 February 2020, Kashiwa Research Complex
17-19 February 2020, Lecture hall

38

Kavli IPMU Annual Report 2019

Kavli IPMU Annual Report 2019

Conferences

6

Awards39

Invited talks given by the Kavli IPMU researchers (Selected 10 of 186)

Date

40

Presenter

Presentation title

Conference name9

Outreach andPublic Relations
TITLE

DATE

VENUE

number ofparticipants

May 20, 2019

Hirosi Ooguri

Swampland and Its Physical Implications SUSY 2019

20th Kavli IPMU/ICRR joint public lecture "Think about the
beginning of the universe"

Apr. 13, 2019

Amuser Kashiwa, Chiba

372

Jun. 14, 2019

Mikhail Kapranov

Perverse schobers and the algebra of
the infrared

Resurgence in Mathematics and Physics

Science Cafe 2019 "Universe"

Jun. 22, 2019

Tamarokuto Science Center,
Tokyo

52

Jul. 1, 2019

Masahiro Takada

Challenges in large-scale structure
cosmology

Dynamics of Large-scale Structure
Formation

Learning and Creating Physics– From High Schools to theForefront Research of the Universe

Aug. 5, 2019

Institute of Industrial Science,
The University of Tokyo,
Tokyo

50

Aug. 2, 2019

Hiraku Nakajima

Bow varieties - I, II

Focus week on quiver varieties

Booth at the 2019 Super Science High School Student Fair

Aug. 7-8, 2019

Kobe International Exhibition
Hall, Hyogo

523

Aug. 5, 2019

Yukinobu Toda

On categorical Donaldson-Thomas
theory for local surfaces

The Conference on algebraic andarithmetic geometry

15th exhibition at Kashiwa Library "Beautiful Mathematics"

Sep. 13-Oct. 10,
2019Kashiwa Library, The Univ. ofTokyo, Chiba

uncounted

Sep. 4, 2019

Shigeki MatsumotoLight Fermionic Thermal Dark Matterwith Light Scalar Mediator

PACIFIC 2019

Science Cafe 2019 "Universe"

Sep. 21, 2019

Tamarokuto Science Center,
Tokyo

36

Sep. 9, 2019

Hitoshi Murayama

Dark matter candidates and strategies
for future

TAUP 2019

Open Campus Kashiwa 2019

Oct. 25-26, 2019

Kashiwa Campus, The Univ.
of Tokyo, Chiba

2,167

Oct. 12, 2019

Misao Sasaki

Perspectives on Gravitational Wave
Cosmology

International Meeting on Gravitational
Wave Physics

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

Nov. 30, 2019

Kavli IPMU, Kashiwa Campus,
The Univ. of Tokyo, Chiba

17

Nov. 17, 2019

Naoyuki Tamura

PFS: The next generation Subaru’s
facility instrument under integration

Subaru Telescope 20th anniversary
conference

21st Kavli IPMU/ICRR joint public lecture "The Forefront of
Universe Exploration"

Dec. 8, 2019

Yasuda Auditorium, The
University of Tokyo, Tokyo420

Dec. 18, 2019Mark Vagins

Supernova Neutrinos in a Gd-loaded SK

NuPhys 2019

8th WPI Science Symposium "The Power of Mathematics:
Bridging Worlds Together"Jan. 12, 2020

Yasuda Auditorium, The
University of Tokyo, Tokyo

481

Kavli IPMU/ELSI/IRCN Joint Public Lecture "A Question of
Origins"

Feb. 16, 2020

Miraikan, Tokyo

158

Kavli IPMU Annual Report 2019

Kavli IPMU Annual Report 2019

Outreach and Public Relations

8

Conference Presentations
and Seminar Talks

41

April 2019–March 2020

5-1-5 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 2019

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