April 2022–March 2023

Kavli IPMUANNUAL REPORT 2022

CONTENTS
FOREWORD

2

1 STATISTICS

4

2 NEWS & EVENTS

8

3 ORGANIZATION

10

4 STAFF

14

5 RESEARCH HIGHLIGHTS

20

5.1 Characteristic Cycle and Its Pushforward ���������������������������������������������������������������������������������������������������������������������������������� 20
5.2 A Novel Proposal to Search for Ultralight Dark Matter Using Atomic Clocks in Space������������������������������������������ 22
5.3 Tensions in Cosmology and How We Infer Them ���������������������������������������������������������������������������������������������������������������� 24
5.4 What Can We Do With Asian-Oceanian Women in Mathematics? ������������������������������������������������������������������������������ 26
5.5 From Space to Ground Applications ������������������������������������������������������������������������������������������������������������������������������������������ 28
5.6 The Case of the Missing Protocluster Shadow ���������������������������������������������������������������������������������������������������������������������� 30
5.7 The Classical Equations of Motion of Quantised Gauge Theories �������������������������������������������������������������������������������� 32
5.8 A New Probe of Inflationary Gravitational Waves: Cross-Correlations of Lensed Primary CMB B-modes		with Large-Scale Structure ������������������������������������������������������������������������������������������������������������������������������������������������������ 34

5.9 Probing the Generalized Symmetry Structure of Quantum Field Theory ���������������������������������������������������������������� 36
5.10 Filaments of the Cosmic Web Shine in the X-rays ���������������������������������������������������������������������������������������������������������������� 38
5.11 MUSSES2020J: The Earliest Discovery of a Fast Blue Ultraluminous Transient at Redshift 1.063 ���������������������� 40

6. AWARDS & HONORS

42

7. CONFERENCES

44

8. CONFERENCE PRESENTATIONS AND SEMINAR TALKS

45

9. OUTREACH AND PUBLIC RELATIONS

46

Copyright © 2023 Kavli IPMU
All rights reserved
Editors: Tomiyoshi Haruyama (Chair), 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/
April 2022–March 2023

Kavli IPMUANNUAL REPORT 2022

On the cover:Group photo at the ceremony for the Kavli IPMU 15th anniversary.

Foreword

Foreword

The long-term strategic planning exercise we undertook in my first year has guided us for the
past five years. The launch of the Center for Data-Driven Discovery this year was part of that plan.
I look forward to the development of the Center and its impact on our science under the leadership of Jia Liu.
Another mission has been to improve our Institute's Equity, Diversity, and Inclusion (EDI). In myinaugural address, I reaffirmed my commitment to EDI, stating, “it is essential that all of us treat
each other with respect, maintain our professional working environment free of harassment,challenge our preconceptions, and educate ourselves on our own biases, so that everyone canbring out the best in themselves.” The Kavli IPMU Diversity Initiative, which we launched two
years ago, is producing tangible results. For example, nearly 40 percent of the new postdoctoral
fellows joining us this year and supported by our operating budget are women. We still have along way to go to reach our EDI goals, and I look forward to further improvements under theleadership of the next Director.
This report showcases the remarkably broad range of research activities at the Kavli IPMU, filledwith creativity and great insight. I hope you enjoy reading it as much as I have.

Hirosi Ooguri
DirectorThank you for your support during my tenure. I am pleased with the improvements we havemade over the past five years and am grateful for the support I have received. Our research in
the Physics and Mathematics of the Universe is thriving, and I am delighted to be able to handover the leadership to my successor, with the Kavli IPMU in such a good shape.
I

Hirosi Ooguri

write this with gratitude as my term as the Director will end on October 14, 2023. It has been
an honor to serve as the Director of this amazing institute for the past five years.

When I became the Director, I set myself two missions.
One was to make the institute permanent. This requires a sustainable business model, bothfinancially and in terms of long-term strategic planning. In terms of finances, thanks to the effortsof our administrative staff members and the support of the Board of Director of the University,
we have secured one billion yen per year in the core funding category of the University of Tokyo
budget. We also increased the Kavli IPMU endowment from $7.5 million to $17.5 million. The
Kavli Foundation continues to support us; for example, this year they announced new funding
for ELSI ethics research led by Hiromi Yokoyama and two inaugural Kavli Fellows, including ourown Kateryna Vovk.

2

Kavli IPMU Annual Report 2022

Kavli IPMU Annual Report 2022

3

STAFF
300

273

285

297 300 291

Total Number of Staff
329
320
311 318303 305

RESEARCH ACTIVITIES
2000

230

1,465*

1500

202

200

1,114* 893*
158

150

165

100

194 209236

259 252 274 279 280 291 265 266
245 255

50

63

21
18
0 3

10
7

22
11

18
Researchers
Research Support Staffs 0
3
Administrative staffs
21
Total

862
478

80 125

500

27
10

25
11

28
10

27
10

30
10

32
10

31
10

29
10

27
10

28
11

29
11

27
11

27
11

28
11

0

63 125 165 194
10 22 27 25
7 11 10 11
80 158 202 230

209
28
10
247

236
27
10
273

245
30
10
285

255
32
10
297

259
31
10
300

252
29
10
291

RESEARCHERS

274
27
10
311

279
28
11
318

280
29
11
320

291
27
11
329

265
27
11
303

266
28
11
305

Percentage of Overseas

300

250

44%
52%

200

56%
150

40% 41%

38%
98
79

105

35%

90

41% 49% 42%
41%

432

28%
17
50
65
28% 46
5
0 13

505

392

463

464 436
688* 768* 1,046*

103
269
372

345
87
432

478
384
862

392
238
630

497 544 471
338 473 457
835 1,017 928

505 464296 264
801 728436 560 463 777* 1,114* 893*
302 465 446 688* 768* 1,046*
738 1,025 909 1,465* 1,882* 1,939*

300

45% 47%
250

124

200

105
150

186 196

94

5 17 60 92 100 79 105 98 105 90 102 111 136 118 135 119 124
13 46 65 73 94 130 131 147 150 169 150 163 143 162 156 146 142
28% 28% 48% 56% 52% 38% 44% 40% 41% 35% 41% 41% 49% 42% 46% 45% 47%
0% 2% 5% 6% 5% 2% 5% 5% 6% 4% 6% 8% 9% 10% 9% 12% 12%232

249 246222
184 192

216 207156 140500Oct. 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 Mar. 2021 Mar. 2022 Mar. 2023

Kavli IPMU Annual Report 2022

497

728 738 560

SEMINARS & CONFERENCES

163 143 162 156 146
147 150 169 150142
130 13173

544 471

630

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 FY 2020 FY 2021 FY 2022

100

60

801

345
168
465 446473 457384
338
296 264 302
65 269
238
103
87

92

100

835

777*
909

Multiple visits in a given year are counted as one.
* Number of participants for online conferences are included from FY2020 onward.

100

48%

372
103

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

46%

111 136 118 135 119
102

1,025

1,017 928

1000

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 Mar. 2021 Mar. 2022 Mar. 2023

4

1,939*

247

250

Overseas
Domestic% of Overseas% of Female

1,882*

Statistics

1

StatisticS

Statistics

Seminars
Conferences

116 117 143
24
4

7

11

16

12

11

14

13

17

14

11

21

18

8

12

12

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 FY 2020 FY 2021 FY 202224
4

156 140 186 196 232 249 246 222 184 192 216 207 116 117 143
7
11 16 12 11 14 13 17 14 11 21 188
12 12

Kavli IPMU Annual Report 2022

5

Statistics

TOTAL EXPENDITURE
589

600
550

519

500

480

450

68

400

78

422
449 449

81

77

544
90
82

3000

202

200

79
70

347 350

60

236

252

40

115

100

20
10

9
9

0

7,540

7,018

1200

6,084
933

4,545

400

4,453

227 379157

163 551

182 167 170 195
130 13547
153 137 143 161 203
40 97 1197 0 33 16 29 30 27 34

316

318

392

439

222

143

410
223 218 219

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 FY 2020 FY 2021 FY 2022

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

Kavli IPMU Annual Report 2022

1,225 1,301 1,024

896

25
25
288
0 132

48
112

783

846

1,259

425
92

538

489

96

90
444

453
93

397
91

387
82

653

574

619

117
88
404

231
80
234

486

486

825

906

987

1,027 1,101 1,023 1,006

295
104

635

730

2,827
2,513
391

335
119

268
98

494

411

265
18
553

523
268
25
647

2,008
385
13
83
233

408

388
948

2,864

925

1,310 1,357 1,286 1,364 1,294

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 FY 2020 FY 2021 FY 2022

BREAKDOWN OF FY 2022 TOTAL EXPENDITURE
7000

5000

13
0.6 %

4000

83
4.1 %

3000

233
11.6 %

385
19.2 %

1,294
64.4 %

2000

174 220

173
304

715
305

541

531
366

1,376

6,484

5,454

4,764 382

3,277

6

5,581

3,339 3,340600

01500 1,366

911

2,991 3,041

6000

1000

800

6,296

6,232

1,842 1,866

1,410
1,524

3,262

Personnel
Project Activities
Travel Expenses
Equipment
Other Research Project

115 202 236 252 347 350 480 449 449 422 519 496 589 563 544
49% 57% 68% 60% 67% 69% 67% 75% 78% 78% 81% 79% 80% 77% 82%

MEDIA COVERAGES AND OUTREACH ACTIVITIES

200

2,362

2000

1000

2,844

2,844

2500

500

CY 2007 CY 2008 CY 2009 CY 2010 CY 2011 CY 2012 CY 2013 CY 2014 CY 2015 CY 2016 CY 2017 CY 2018 CY 2019 CY 2020 CY 2021 CY 2022

Publications% of int'l collaboration

2,707

80

30

150

3,372 3,425

50

250

0

67

78

80

3500

49

300

50

60

57

350

69

67

75

496

563

(%)
100

(1,000,000 JPY)

3,910 3,902

Statistics

PUBLICATIONS

1000
0(1,000,000 JPY)
Personnel
Project Activities
Travel Expenses
Equipment
Other Research Project

Kavli IPMU Annual Report 2022

7

APRIL>> Researchers use muonic X-rays to find elemental
makeup of samples without damaging them>> Hiromi Yokoyama appointed new Deputy Directorof Kavli IPMU>> Yukari Ito selected as new member of The
Association of Academies and Societies of Sciencesin Asia’s Women in Science and Engineering
Committee>> Researchers adapt technology made forastronomical observations to biomedical imaging>> Kyiv Formula and Related Aspects (Online)>> Extensive training on virtual universes fromsupercomputer simulations produces AI-assisted
analysis of three-dimensional galaxy distribution in
our Universe>> Millisecond Pulsars can explain the Gamma-ray
Excess in the Milky Way center

April 2022 - March 2023

JULY>> Informal Open House for the University of Tokyo
Physics Major PhD Program>> Hiraku Nakajima elected President of theInternational Mathematical Union>> Researchers capture the first example of an
extremely bright, and fast-evolving astronomical
event in the distant universe>> Non-linear Aspects of Cosmological Gravitational
Waves>> Director Hirosi Ooguri gives closing talk at Strings
2022>> First results from a Search for New Physics inElectronic Recoils from XENONnTAUGUST
MAY>> Yukari Ito selected as executive committee memberof the Asia-Oceania Women in Mathematics

OCTOBER>> Alexander Kusenko appointed Associate Editor of
Reviews of Modern Physics>> Hirosi Ooguri receives Science Lectureship Award>> Researchers measure size-luminosity relation ofgalaxies less than a billion years after Big Bang>> HirosiFest @ Kavli IPMUNOVEMBER

JUNE>> Researchers create ‘time machine’ simulations
studying the lifecycle of ancestor galaxy cities>> Hiromi Yokoyama awarded the Tokyo Academy ofPhysics Award>> Hyper-Kamiokande Collaboration Meeting (Online)>> Geometric Representation Theory (Online)

8

Kavli IPMU Annual Report 2022>> Researchers develop a new way to see how people
feel about Artificial Intelligence>> Researchers use gamma rays to detect smallneighboring galaxy filled with Dark Matter>> State Minister of MEXT Yosei Ide visits Kavli IPMUFEBRUARY>> Current Trends in Categorically Approach to
Algebraic and Symplectic Geometry>> Geometry and Automorphicity of SupersymmetricPartitions (GASP)>> ISAS/JAXA Director General Hitoshi Kuninaka visits
Kavli IPMU>> Gauge Theory, Moduli Spaces and Representation
Theory -In Honor of the 60th Birthday of Hiraku
Nakajima>> Interdisciplinary Science Conference in Okinawa(ISCO 2023) -Physics and Mathematics Meet Medical
Science->> Kavli IPMU Senior Fellow Eiichiro Komatsu Receives
Nishina Memorial Prize>> Prime Focus Spectrograph passes significant testing
milestone to capture light from many stars at once>> Hitoshi Murayama named Chair of P5 Committee>> Kavli IPMU Annual Report 2021 released>> COVID-19 has had positive effect on astronomy
research, but negative effect on new and female
researchers

MARCH>> National Academy of Sciences elects Takaaki Kajita
as new international member>> Researchers hunt for one-pole magnets bycombining cosmic rays and particle accelerators

SEPTEMBER

News & Events

2

NEWS & EVENTSNews & Events

DECEMBER>> What the Heck Happens When the Universe Boils?
>> Filaments of the cosmic web shine in the X-rays in
the early eROSITA survey data>> Researchers say space atomic clocks could help
uncover the nature of dark matter>> Masahito Yamazaki awarded the 19th JSPS Prize>> PFS Collaboration Meeting>> FY2022 “What Is Dark Matter? - Comprehensive
Study of the Huge Discovery Space in Dark Matter”>> Researchers uncover the first bubble in anintergalactic stew>> Instrument adapted from astronomy observation
helps capture singular quantum interference effects>> Artificial intelligence finds the first stars were notalone>> First WIMP Search Results from the XENONnT>> Center of Data-Driven Discovery launched in the
Kavli IPMU

Kavli IPMU Annual Report 2022

9

Kavli IPMU

Kavli IPMU Management

President
Teruo Fujii

UTIAS

Director

Director: Hiroaki Aihara

Kavli IPMU External
Advisory Committee

Hirosi Ooguri

Administrative
Director

Tomiyoshi Haruyama

Assistant Administrative
Director

Deputy Directors

Hiroaki Aihara
Misao Sasaki
Tomiyoshi Haruyama
Hiromi Yokoyama

Junichi Kanzaki

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 obliged to report the appointments of new
faculty members to the Director of UTIAS. Also, to clear theuniversity’s formality in faculty hiring, the decisions of theInstitute have to be endorsed by the Steering Committee ofthe Kavli IPMU.

The Director is appointed by the Director of the University ofTokyo Institutes for Advanced Studies (UTIAS). The Director
has complete authority to hire research staff and administrative staff. He is also solely responsible for making all otherdecisions. He is assisted by the four Deputy Directors and theAdministrative Director. They constitute the Executive Board(EB) and regularly meet to ensure the 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 External Advisory Committee (EAC), appointed by the
Director of the Kavli IPMU, reviews annually the scientificachievement and activities of the Institute and advises the
Director on scientific properties and the research activities tokeep the Institute stay on the course of the objectives.

The Principal Investigator scheme is abolished, and all the Full
Professors at Kavli IPMU are regarded as equivalent to PIs.

Organization

3

ORGANIZATION

Organization

Steering Committee
Executive Board
Chair

Hirosi Ooguri
Hiroaki Aihara
Misao Sasaki
Tomiyoshi Haruyama		
Hiromi Yokoyama

Director
Deputy Director
Deputy Director
Administrative Director/Deputy Director
Deputy Director

Mikhail Kapranov
Masahiro Takada
Mark Vagins

The External Advisory Committee Members (March 2021)
John Ellis
Giovanni Felder
Joshua Frieman
Masahiko Hayashi
Tatsuya Nakada
Yongbin Ruan
Sakura Schafer-Nameki
Nigel Smith

King’s College London
ETH Zürich
FNAL/U Chicago; Chair
JSPS Bonn Office
EPFL
Zhejiang University
U Oxford
TRIUMF

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

Kavli IPMU Research

Faculty, Postdocs, Students, Visitors

10

Kavli IPMU Annual Report 2022

Kavli IPMU Annual Report 2022

11

Organization

experiments 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.

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.

Foreign institutions/consortia/programs having MOU with the Kavli IPMU

Host InstituteCollaborating Institutions(The Univ. of Tokyo)(domestic)

National Astronomical
Observatory in Japan Department of Mathematics
 Institute for Cosmic Ray Research(Kashiwa, Kamioka) Department of Physics
 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

12

Kavli IPMU Annual Report 2022

Kavli IPMU
Kashiwa Campus
Kamioka Branch

Berkeley
Satellite

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

Kavli IPMU Annual Report 2022

13

4

Staff

Director
Hirosi Ooguri, Mathematical Physics

Deputy Directors
Hiroaki Aihara (U Tokyo), High Energy Physics
Tomiyoshi Haruyama, High Energy Physics
Misao Sasaki, Cosmology
Hiromi Yokoyama, Science and Society

Senior Fellow
Alexey Bondal (Steklov Math. Inst.), Mathematics (from2022/5/1)
Takaaki Kajita (U Tokyo, ICRR), Neutrino Physics (from2022/5/1)
Eiichiro Komatsu (MPI for Astrophysics), Cosmology (from2022/5/1)
Masayuki Nakahata (U Tokyo, ICRR), Astroparticle Physics

14

Kavli IPMU Annual Report 2022

Kentaro Hori, String Theory
Shunsaku Horiuchi (Virginia Tech), Theoretical Physics (till2022/8/9)
Yukari Ito, Mathematics
Mikhail Kapranov, Mathematics
Nobuhiko Katayama, High Energy Physics (till 2023/3/31)
Khee-Gan Lee, Astronomy
Jia Liu, Cosmology
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
Toshiya Namikawa, Cosmology
Andrei Okounkov (UC Berkeley), Mathematics (till2022/5/31)
Hirosi Ooguri (CALTECH), Mathematical Physics
Tadashi Orita, Experimental Physics
Misao Sasaki, Cosmology
Satoshi Shirai, Particle Theory
John David Silverman, Astronomy
Yuji Tachikawa, Particle Theory
Masahiro Takada, Cosmology
Tadayuki Takahashi, Experimental Physics
Shinichiro Takeda, Experimental Physics
Naoyuki Tamura, Astronomy (till 2023/3/31)
Yukinobu Toda, Mathematics
Mark Robert Vagins, Astroparticle Physics
Taizan Watari, Theoretical Physics
Atsushi Yagishita, Experimental Physics
Masaki Yamashita, Astrophysics
Masahito Yamazaki, String Theory
Naoki Yasuda, Astronomy
Hiromi Yokoyama, Science and Society
Naoki Yoshida (U Tokyo), Astrophysics(from 2022/5/1)
Mihoko Nojiri (KEK), Particle Theory (from 2022/5/1)
Andrei Okounkov (Columbia U), Mathematics (from2022/6/1)
Naoshi Sugiyama (Nagoya U), Cosmology (from 2022/5/1)

Faculty Members
Tomoyuki Abe, Mathematics
Hiroaki Aihara (U Tokyo), High Energy Physics
Alexey Bondal (Steklov Math. Inst.), Mathematics (2022/10/42023/2/15)
Patrick De Perio, Neutrino Physics (from 2022/4/1)
Elisa Gouvea Mauricio Ferreira, Cosmology
Mark Patrick Hartz, Neutrino Physics
Tomiyoshi Haruyama, High Energy Physics
Simeon John Hellerman, String Theory
Takeo Higuchi, High Energy Physics

Project Researchers
Noah Maxwell Arbesfeld, Mathematics (till 2023/3/31)
Joaquin Andres Armijo Torres, Cosmology (from 2022/10/1)
Meer Ashwinkumar, String Theory
Metin Ata, Cosmology (till 2022/9/30)
Jahmall Matteo Bersini, Theoretical Physics (from 2022/11/1)
Tobias Binder, Theoretical Physics (till 2022/4/30)
Connor Hugh Bottrell, Astrophysics
Philip Ewen Boyle Smith, Theoretical Physics
Tuan Khai Bui, Experimental Physics (till 2023/3/31)
Anqi Chen, Cosmology
Man Wai Cheung, Mathematics (from 2022/10/1)
Ioana Alexandra Coman Lohi, Theoretical Physics (from2022/11/1)
Anton Reyes De La Fuente, String Theory (till 2022/6/30)
Xuheng Ding, Astronomy

Zhiyuan Ding, Mathematics (till 2022/8/31)
Joshua Armstrong Eby, Cosmology
Dmitrii Galakhov, String Theory (till 2022/8/31)
Naoki Genra, Mathematics (till 2023/3/31)
Tommaso Ghigna, Experimental Physics (till 2022/7/31)
Ryuichiro Hada, Cosmology (2022/4/1-8/31)
Norihiro Hanihara, Mathematics
Takashi Hasebe, High Energy Physics (till 2023/3/31)
Thuong Duc Hoang, Experimental Physics
Shunichi Horigome, Theoretical Physics
Derek Beattie Inman, Cosmology
Kazuhiro Ito, Mathematics
Cesar Jesus Valls, Neutrino Physics (from 2022/10/1)
Baptiste Jost, Cosmology (from 2023/2/1)
Boris Sindhu Kalita, Astrophysics (from 2023/1/16)
Kookhyun Kang, High Energy Physics
Dogancan Karabas, Mathematics (from 2022/10/1)
Miho Katsuragawa, Experimental Physics
Ilya Khrykin, Astrophysics
Tasuki Kinjo, Mathematics (2022/10/1-2023/3/31)
Takafumi Kokubu, Theoretical Physics
Yun-Tsung Lai, High Energy Physics (till 2022/9/30)
Clement Leloup, Cosmology (from 2022/10/1)
Kaloian Dimitrov Lozanov, Cosmology (from 2022/11/1)
Abhiram Mamandur Kidambi, Mathematical Physics
Mohammad Khaled Hashem Mardini, Astronomy
Dmytro Matvieievskyi, Mathematics (from 2022/9/1)
Katherine Alston Maxwell, Mathematics (from 2022/9/1)
Yue Nan, Cosmology (from 2022/4/1)
Emily Margaret Nardoni, Theoretical Physics
Ippei Obata, Theoretical Physics (from 2022/10/1)
Youngsoo Park, Cosmology (till 2022/9/15)
Samuel Charles Passaglia, Cosmology
Ipsita Saha, Particle Theory (2022/6/1-9/12)
Jingjing Shi, Cosmology
Myungbo Shim, Theoretical Physics (from 2022/8/29)
Tomoko Suzuki, Astronomy
Volodymyr Takhistov, Theoretical Physics (till 2022/8/31)
Hideki Tanimura, Astrophysics (from 2022/10/1)
Ka Ming Tsui, Neutrino Physics (from 2022/12/1)
Izumi Umeda, Nuclear Medicine (till 2023/3/31)
Valeri Vardanyan, Cosmology
Kateryna Vovk, Astronomy (from 2022/12/16)
Graham Albert White, Particle Theory
Junjie Xia, Neutrino Physics (from 2022/11/1)
Kiyoto Yabe, Astronomy (till 2023/3/31)
Lilan Yang, Astronomy
Hassen Yesuf, Astronomy (till 2023/2/28)
Wai Kit Yeung, Mathematics (till 2023/1/31)
Vicharit Yingcharoenrat, Cosmology
Yu Zhao, Mathematics
Yunqin Zheng, Theoretical Physics
Yehao Zhou, Mathematical Physics (from 2022/10/16)
Zijun Zhou, Mathematics
Kavli IPMU Annual Report 2022

Staff

Staff

15

Joint Appointments
Mark Patrick Hartz (TRIUMF), Neutrino Physics
Masashi Hazumi (KEK), High Energy Physics
Hitoshi Murayama (UC Berkeley), Particle Theory
Hirosi Ooguri (CALTECH), Mathematical Physics
Naoki Yoshida (U Tokyo), Astrophysics

Affiliate Members
Ko Abe (U Tokyo, ICRR), Astroparticle Physics
Shin'ichiro Ando (U Amsterdam), Astroparticle Physics
Metin Ata (Stockholm U), Cosmology (2022/10/1-2023/3/31)
Bruce Berger (LBL, Berkeley (LBNL)), Neutrino Physics (till2023/3/31)
Melina Bersten (IALP CONICET-UNLP), Astronomy (till2023/3/31)
Sergey Blinnikov (ITEP), Astronomy
Agnieszka Maria Bodzenta-Skibinska (U Warsaw),
Mathematics
Alexey Bondal (Steklov Math. Inst.), Mathematics
Kevin Allen Bundy (UC Santa Cruz), Astronomy
Andrew Bunker (U Oxford), Astrophysics
Scott Huai-Lei Carnahan (U Tsukuba), Mathematics
Cheng-Wei Chiang (Natl Taiwan U), Particle Theory
Yuji Chinone (KEK), Astronomy
Neal Krishnakant Dalal (Perimeter Institute), Astrophysics
Patrick Decowski (U Amsterdam/GRAPPA), Neutrino Physics
Jason Detwiler (U Washington, Seattle), Neutrino Physics
Mamoru Doi (U Tokyo, IoA), Astronomy
Christine Done (Durham U), Astrophysics
William Ross Goodchild Donovan (Tsinghua U, Beijing),
Mathematics
Yuri Efremenko (U Tennessee), Neutrino Physics (till2023/3/31)
Motoi Endo (KEK), Particle Theory
Sanshiro Enomoto (U Washington, Seattle), Neutrino Physics
Gaston Folatelli (IALP CONICET-UNLP), Astrophysics (till2023/3/31)
Andreu Font-Ribera (IFAE), Cosmology (till 2023/3/31)
Brian Fujikawa (LBL, Berkeley), Neutrino Physics
Masataka Fukugita (U Tokyo), Astrophysics
Shao-Feng Ge (Shanghai Jiao Tong U), Theoretical Physics
Paolo Gondolo (U Utah), Cosmology (till 2023/3/31)
Lawrence J Hall (UC Berkeley), Particle Theory
Koichi Hamaguchi (U Tokyo), Particle Theory
Jiaxin Han (Shanghai Jiao Tong U), Astronomy (till 2023/3/31)
Keisuke Harigaya (U Chicago), Particle Theory (from2022/9/1)
Tilman Hartwig (U Tokyo), Astrophysics (till 2023/3/31)
Tetsuo Hatsuda (RIKEN), Nuclear Physics
Yoshinari Hayato (U Tokyo, ICRR), Neutrino Physics
Katsuki Hiraide (U Tokyo, ICRR), Astroparticle Physics
Raphael Hirschi (Keele University), Astronomy
Junji Hisano (Nagoya U), Particle Theory
Shunsaku Horiuchi (Virginia Tech), Theoretical Physics (from16

Kavli IPMU Annual Report 2022

2022/8/10)
Kenta Hotokezaka (U Tokyo, School of Sci), Astrophysics
Masahiro Ibe (U Tokyo, ICRR), Particle Theory
Kei Ieki (U Tokyo, ICRR), Neutrino Physics
Motoyasu Ikeda (U Tokyo, ICRR), High Energy Physics
Shiro Ikeda (ISM), Mathematics
Yuko Ikkatai (Kanazawa U), Science and Society
Yoshiyuki Inoue (Osaka U), Astrophysics
Miho N. Ishigaki (NAOJ, Hawaii), Astronomy
Ken'ichi Izawa (Tokushima U) (till 2023/3/31)
Nicholas Kaiser (ENS PSL), Cosmology (till 2023/3/31)
Jun Kameda (U Tokyo, ICRR), Neutrino Physics
Yousuke Kanayama (RIKEN), Experimental Physics (till2023/3/31)
Amanda Irene Karakas (Monash U), Astronomy (till2023/3/31)
Kazumi Kashiyama (Tohoku U), Astronomy
Yosuke Kataoka (U Tokyo, ICRR), Neutrino Physics
Akishi Kato (U Tokyo, Math Sci), Mathematical Physics
Yasuyuki Kawahigashi (U Tokyo, Math Sci), Mathematics
Masahiro Kawasaki (U Tokyo, ICRR), Cosmology
Edward T. Kearns (Boston U), Neutrino Physics
Sergey Ketov (Tokyo Metropolitan U), Theoretical Physics
Yasuhiro Kishimoto (Tohoku U), Neutrino Physics
Ryuichiro Kitano (KEK), Particle Theory
Chiaki Kobayashi (U Hertfordshire ), Astronomy
Toshiyuki Kobayashi (U Tokyo, Math Sci), Mathematics
Masayuki Koga (Tohoku U), Neutrino Physics
Toshitake Kohno (Meiji U), Mathematics
Kazunori Kohri (KEK), Cosmology
Eiichiro Komatsu (MPI for Astrophysics), Cosmology
Satoshi Kondo (Middle East Technical U), Mathematics
Yusuke Koshio (Okayama U), Neutrino Physics
Akito Kusaka (U Tokyo), Experimental Physics
Alexander Kusenko (UCLA), Particle Theory
Tatsuki Kuwagaki (Kyoto U), Mathematics
Alexie Solange Leauthaud Harnett (UC Santa Cruz),
Astrophysics
Shiu-Hang (Herman) Lee (Kyoto U), Astrophysics
Marco Limongi (INAF), Astrophysics (till 2023/3/31)
Kazuo Makishima (U Tokyo), High Energy Physics
Ryu Makiya (Company), Astronomy (till 2022/7/31)
Brice Menard (Johns Hopkins U), Astrophysics (till 2023/3/31)
Makoto Miura (U Tokyo, ICRR), High Energy Physics
Hironao Miyatake (Nagoya U), High Energy Physics
Hiroshi Mizuma (QST), Experimental Physics
Anupreeta Sadashiv More (IUCAA), Astronomy
Surhud Shrikant More (IUCAA), Astronomy
Yuki Moritani (NAOJ, Hawaii), Astronomy
Shigetaka Moriyama (U Tokyo, ICRR), Neutrino Physics
Takeo Moroi (U Tokyo), Particle Theory
David Robert Morrison (UC Santa Barbara), Mathematics
Shinji Mukohyama (Kyoto U), Cosmology
Motohico Mulase (UC Davis), Mathematics

Dinakar Muthiah (U Glasgow), Mathematics
Kentaro Nagamine (Osaka U), Astrophysics
Yasuhiro Nakajima (U Tokyo, School of Sci), Neutrino Physics
Yusuke Nakajima (Kyoto Sangyo U), Mathematics (from2022/11/1)
Kenzo Nakamura (KEK), Neutrino Physics
Tsuyoshi Nakaya (Kyoto U), High Energy Physics
Kazunori Nakayama (Tohoku U), Cosmology
Shoei Nakayama (U Tokyo, ICRR), Neutrino Physics
Takahiro Nishimichi (Kyoto U), Cosmology
Ken'ichi Nomoto (U Tokyo ), Astronomy
Yasunori Nomura (UC Berkeley), Particle Theory
Hirokazu Odaka (Osaka U), High Energy Astrophysics
Masamune Oguri (Chiba U), 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 (till2023/3/31)
Domenico Orlando (INFN), String Theory
Masaki Oshikawa (U Tokyo, ISSP), Theoretical Physics
Masami Ouchi (U Tokyo, ICRR), Astronomy
Serguey Todorov Petcov (SISSA), Particle Theory
Shi Pi (Chinese Academy of Sciences), Astrophysics
Jason Xavier Prochaska (UC Santa Cruz), Astronomy
Anna Puskas (U Queensland), Mathematics
Robert Michael Quimby (San Diego State U), Astronomy
Susanne Reffert (U Bern), String Theory
Jason Rhodes (NASA JPL/Caltech), Cosmology
Joshua Thomas Ruderman (New York Univ.), Particle Theory
Wiphu Rujopakarn (Chulalongkorn U), Astronomy (till2023/3/31)
Kyoji Saito (Kyoto U), Mathematics
Ryo Saito (Yamaguchi U), Astrophysics
Shun Saito (Missouri U of Sci and Tech), Cosmology
Yoshihisa Saito (Rikkyo U.), Mathematics
Francesco Sala (U Pisa), Mathematics
Katsuhiko Sato (U Tokyo), Astroparticle Physics
Vadim Schechtman (U Toulouse III-Paul Sabatier),
Mathematics
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
Gary Shiu (U Wisconsin, Madison ), String Theory
Aurora Simionescu (Netherlands Inst for Space Res),
Astrophysics
Michael Smy (UC Irvine), Neutrino Physics
Yevgeny Stadnik (U Sydney), Theoretical Physics
Samantha Lynn Stever (Okayama U), Astrophysics
James L. Stone (Boston U), High Energy Physics (till2023/3/31)
Shigeki Sugimoto (Kyoto U), Theoretical Physics
Nao Suzuki (LBL, Berkeley (LBNL)), Astrophysics

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
Volodymyr Takhistov (KEK), Theoretical Physics (from2022/9/1)
Hidekazu Tanaka (U Tokyo, ICRR), Neutrino Physics
Masaomi Tanaka (Tohoku U), Astronomy
Atsushi Taruya (Kyoto U), Astrophysics
Nozomu Tominaga (NAOJ), Astrophysics (till 2023/3/31)
Werner Tornow (Duke U), Neutrino Physics (till 2023/3/31)
Sachiko Tsuruta (Montana State U), Astrophysics (till2023/3/31)
Edwin L Turner (Princeton U), Astrophysics
Kazushi Ueda (U Tokyo, Math Sci), Mathematics
Hokuto Uehara (Tokyo Metropolitan U), Mathematics
Alexander Voronov (U Minnesota), Mathematics
Christopher W. Walter (Duke U), Neutrino Physics
Shin Watanabe (JAXA), Experimental Physics
Bryan Webber (U Cambridge), Particle Theory (till 2023/3/31)
Roger Alexandre Wendell (Kyoto U), Neutrino Physics (till2023/3/31)
Marcus Christian Werner (Duke Kunshan U), Mathematical
Physics
Benda Xu (Tsinghua U), Experimental Physics
Tsutomu Yanagida (Shanghai Jiao Tong U), Particle Theory
Jun'ichi Yokoyama (U Tokyo, School of Sci), Cosmology
Masashi Yokoyama (U Tokyo), High Energy Physics
Shuichiro Yokoyama (Nagoya U), Cosmology
Ying-li (Yingli) Zhang (Tongji U), Cosmology

Staff

Staff

Graduate Students
Yuto Arai, Mathematics
Weiguang Cao, Theoretical Physics
Chenze Dong, Astronomy (from 2022/10/1)
Sho Egusa, String Theory (till 2023/3/31)
Yuichi Enoki, Particle Theory (till 2023/3/31)
Linghu Fan, Mathematics
Saki Fujita, Experimental Physics
Kota Hayashi, Cosmology
Tatsuya Hayashi, Cosmology
Kyosuke Higashida, Mathematics
Yuxin Huang, Astronomy
Tomohiro Karube, Mathematics
Tenyo Kawamura, Experimental Physics (till 2023/3/31)
Kotaro Kawasumi, String Theory
Tasuki Kinjo, Mathematics (till 2022/9/30)
Dan Kondo, Particle Theory
Toshiki Kurita, Cosmology (till 2023/3/31)
Peijang Liu, Mathematics
Zhaoxuan Liu, Astronomy (from 2022/10/1)
Ryusei Maeda, Theoretical Physics (till 2023/3/31)
Kavli IPMU Annual Report 2022

17

StaffAdministration

Public Relations

Tomiyoshi Haruyama, Administrative Director,
Project Professor
Junichi Kanzaki, Assistant Administrative Director,
Project Lecturer
Kouji Yoshiizumi, General Manager (from 2022/4/1)
Masayuki Tomita, Senior Specialist (till 2023/3/31)

Koushi Chiba (2022/5/1-2023/3/31)
Motoko Kakubayashi
Marina Komori
Aya Tsuboi

Accounting
Masataka Tanaka*
Takako Okawa
Hiromi Yoshida
Yukiko Yoshikawa

Kamioka Branch
Hideaki Abe* (from 2022/4/1)
Masako Ishikura
Yoshimi Kakioka
Hitoshi Nakagawa(*section head)

Budget Control
Daisuke Hamada* (till 2022/6/30)
Takuya Tanigaichi* (from 2022/7/1)
Rie Kohama
Madoka Okamoto
Kaori Watanabe

Staff

Tianle Mao, Mathematics
Takahiro Minami, Experimental Physics
Kai Murai, Particle Theory (till 2023/3/31)
Shunsaku Nagasawa, Experimental Physics
Kanade Nishikawa, Particle Theory
Kanmi Nose, Cosmology
Risshin Okabe, Particle Theory
Masaki Okada, Theoretical Physics
Fumiaki Otani, Experimental Physics
Tian Qiu, Cosmology
Renji Sakamoto, Mathematics
Yotaro Sato, Theoretical Physics
Yuta Sato, Particle Theory (till 2023/3/31)
Tomoyuki Shimasaki, Experimental Physics
Yusuke Suetake, String Theory
Sunao Sugiyama, Cosmology (till 2023/3/31)
Shenli Tang, Astronomy
Takanori Taniguchi, Cosmology
Ryo Terasawa, Cosmology
Akira Tokiwa, Cosmology
Yutaka Tsuzuki, Experimental Physics (till 2023/3/31)
Akihiro Watanabe, String Theory
Yu Watanabe, Particle Theory
Yuki Watanabe, Cosmology
Xia Xiaokun, Mathematics
Fanli Zeng, High Energy Physics (from 2022/10/1)
Chenghan Zha, Mathematics (till 2023/3/31)

Contract & General Purchasing
Noboru Abe*
Naoko Ishida
Yuri Kazama
Sachiko Shimada
Tomoko Yamanaka

General Management
Manabu Hirano*
Yuuko Enomoto
Mika Miura
Ayako Nakada
Mana Shindo
Rieko Tamura

International Relations and Researchers Support
Yuko Fukuda*
Masami Nishikawa
Yuhi Ota (from 2022/4/1)
Tomoko Shiga
Eri Shinoda

Network & Web Service
Satoko Inoshita
Masahiro Kawada

Planning & Assessment
Shoko Ichikawa

18

Kavli IPMU Annual Report 2022

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5

RESEARCH HIGHLIGHTS

Research Highlights

5.1 Characteristic Cycle and Its Pushforward
Tomoyuki Abe

Now, consider a smooth variety over ℂ, namely the geometric object given by zeros of polynomials with ℂ-coefficients
which doesn’t have singularities. In this situation, we can also consider the EP characteristic by regarding the variety as amanifold. Assume that we are a covering f : X → Y. Namely, this is a locally homeomorphism such that the function which–1associates # f ( 𝑦 ) to a point 𝑦 of Y is finite and constant whose value is denoted by deg ( f ). Then it is not hard to showthat
𝜒 ( X ) = deg ( f ) 𝜒 ( Y ).
(*)

Motivated by Weil’s conjecture, Grothendieck and his school constructed a similar theory for varieties over more exotic field,say finite field 𝔽p. Varieties over 𝔽p is a priori a very discrete object, but his theory enables us to extract “topological invariants” like EP characteristic from such varieties. However, Grothendieck noticed that the formula ( * ) doesn’t hold anymore
even in the case where Y (and consequently X as well) is a curve. He asked Serre how to understand the difference in the
curve case, and Serre suggested to consider the local invariant called the Swan conductor. This is the genesis of ramification
theory. Ramification theory explains the difference as contributions from the “boundary” of Y, and Grothendieck showed
his famous Grothendieck-Ogg-Shafarevich (GOS) formula. We note that the appearance of ramification is not particular to
number theory. Somewhere in 70’s, it was observed by experts including Deligne and Laumon that the ramification
behaves similarly to irregularity of linear differential equations over complex field. This observation would become important in the further development of ramification theory, which we will come back below.

In the case of curves, we can retrieve GOS formula from the index formula, and the index formula can be regarded as a
generalization. Considering the philosophy of Grothendieck-Riemann-Roch theory, it is natural to expect its “relative version”. In fact, this was formulated by Saito and left as a conjecture. Saito’s pushforward conjecture states as follows: Letf : X → Y be a proper morphism between smooth varieties. Under this situation, we may define the pushforward of cycles**
1
f o : CH dim (x) ( T X ) → CH dim (Y) ( T Y ). The (weak version of) pushforward conjecture states thatf o : ( CC ( ℱ )) = CC ( R f* ℱ ).

Saito himself verified the conjecture in specific (but important) cases. I proved2 this conjecture up to p-torsion. One of thereasons why the proof of the identity is so hard is that it is not a coincidence of actual cycles but we need to construct ahomotopy between them. To overcome this difficulty we need various techniques, notably the theory of ∞-categories, thetheory of nearby cycle over higher dimensional bases, and the motivic homotopy theory. Another important input is anidea from p-adic cohomology theory, especially the idea of the proof of the semistable reduction theorem. To define thecharacteristic cycle, we need to choose nice functions. The existence of such functions is exactly where we need Beilinson’s
existence of singular support in the construction of characteristic cycle by Saito. To show the pushforward conjecture, weneed to upgrade this to the family version, and this is where the ideas from semistable reduction theorem is required.

Research Highlights

Assume we want to classify (closed compact) surface topologically. For example, let S be the surface of a sphere, and D bethat of donuts. How can we distinguish these two surfaces? One of the very classical answers, going back to Euler, is to pay
attention to the number of “holes” of the surface. In our example, S has no hole, contrary to D having one hole in the center.
Poincare proved that in fact surfaces can be classified (topologically) by this invariant, and the number of holes is now called
the Euler-Poincaré characteristic (EP characteristic for short). This invariant can also be defined for higher dimensional manifolds, and it is one of the most important invariants when we want to understand the manifold topologically.

A natural question is to generalize this formula to higher dimensional situation. This question turns out to be very hard.
Even the formulation is not clear: in the curve case the boundary of Y consists of finitely many points, so associating a
number to each point is reasonable. However, in the higher dimensional setup, the boundary does not necessarily consistof finitely many points but rather itself a higher dimensional variety. Thus, it is natural to expect that the geometry of theboundary also contributes to the difference of EP characteristics.
After numerous studies of ramifications of higher dimensional variety, notably by Deligne, Laumon, Bloch, K. Kato, etc.,
Takeshi Saito finally gave a definitive answer in around 2015 after the existence of “singular support” by Beilinson. The formulation was suggested by the theory of 𝒟-modules, which is an algebraic theory of linear partial differential equations, as
I alluded. Let X be a smooth variety over 𝔽p. For a (étale) sheaf ℱ on X, Saito defines a middle dimensional cycle in the*
cotangent bundle T X called the characteristic cycle and denoted by CC(ℱ). When X is a curve, this can be described in termsof Swan conductor. After suggestions of Deligne and Beilinson, Saito also showed the index formula, namely when X is
projective as well, we have
𝜒 ( X , ℱ ) = deg ( CC ( ℱ), [ X ]).

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Kavli IPMU Annual Report 2022

1
2

Original conjecture of Saito is stronger, but for simplicity of the presentation, we only state the weaker version.
Abe, T.: “Ramification theory from homotopical point of view, I”, arxiv.org/abs/2206.02401.
Kavli IPMU Annual Report 2022

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Research Highlights

5.2 A Novel Proposal to Search for Ultralight
Dark Matter Using Atomic Clocks in Space
Joshua Armstrong Eby
Our recent work investigated a novel way to potentially learn the nature of dark matter, which is a mysterious substancewhich makes up a large fraction of the mass in the universe. Our proposal involves an atomic clock search on-board a
spacecraft in the inner reaches of the solar system, inside the orbit of Mercury and very near to the Sun. An important
advantage in this search is that in this region of the solar system, the density of dark matter may be exceedingly large, leading to exceptional sensitivity to dark matter signals. Our work was published in the journal Nature Astronomy on December
5, 2022 [1].
Recent advances in the study of atomic and nuclear systems have opened the door to many novel searches for dark matterwith extremely high sensitivity [2]. These systems are capable of probing dark matter particles which have very small
masses, because large collections of such particles naturally oscillate with wavelengths that are intrinsically macroscopic. As
a result, their interactions with ordinary matter (including photons and electrons) can induce apparent oscillations of thefundamental constants of nature, including the interaction strength of the electromagnetic force or the mass of the electron. These oscillations therefore induce changes in the energies observed in atomic or nuclear transitions, allowing us tosearch for effects from dark matter in these systems.

References[1] Y. -D. Tsai, J. Eby, and M. S. Safronova, Direct detection of ultralight dark matter bound to the Sun with space quantum sensors. Nature Astronomy 7 (2023) 1, 113-121. [arXiv:2112.07674 [hep-ph]][2] M. S. Safronova, D. Budker, D. DeMille, D. F. Jackson Kimball, A. Derevianko, and C. W. Clark, Search for New Physics with
Atoms and Molecules. Rev. Mod. Phys. 90 (2018) 2, 025008. [arXiv: 1710.01833 [physics.atom-ph]][3] D. Budker, J. Eby, M. Gorghetto, M. Jiang, and G. Perez, A Generic Formation Mechanism for Ultralight Dark Matter Solar
Halos. Under review by JCAP. [arXiv:2306.12477 [hep-ph]][4] Alanso et al., Cold atoms in space: community workshop summary and proposed road-map. EPJ Quant. Technol. 9 (2022) 1,
30. [arXiv: 2201.07789 [astro.ph.IM]]

Research Highlights

Any search for dark matter relies on a key assumption about the so-called local density of dark matter, which determines thenumber of dark matter particles passing through the detector at any given time and therefore the experimental sensitivity.
The density can be much higher than is usually assumed if the dark matter can be captured into stable bound configurations, which is a topic of vibrant recent discussion in recent literature. There is good reason to believe that the strong gravitational field of the Sun provides an effective trap for these dark particles, leading to a large overdensity very near the Sun.
In a separate work (still in preprint) with other collaborators, I have established a novel mechanism to capture ultralightparticles around the Sun using dark matter self-interactions, providing a concrete target for the searches proposed in thiswork [3].
While the precise density of the dark matter near the Sun depends on the details of the model, we show in our work how
even a relatively low-sensitivity search can provide important information. The current strongest constraints on the dark
matter density in the solar system comes from observations of the orbits of planets, and therefore in the region between
Mercury and the Sun, the constraints are extremely weak. Our proposal combines the two above insights: We seek to utilize
the high precision of modern atomic and nuclear clocks in a very novel environment (near the Sun), where the dark matter
density may be much higher than normal. Such a probe could therefore provide world-leading limits on accumulation ofultralight particles near the Sun, or even lead to a dark matter discovery.
The proposed space mission is partly motivated by several ongoing missions from organizations around the world. For
example, the NASA Parker Solar Probe has been in operation since 2018 has travelled closer to the Sun than any humanmade craft in history, with the help of cutting-edge heat-shield technology. At present, the Parker Solar Probe is operating
inside the orbit of Mercury, and will approach its target distance, deep inside the solar coronal radius, within the year.
Another mission, the NASA Deep Space Atomic Clock, has demonstrated that atomic clocks can be operated in space withvery little loss in precision, providing additional indirect support for our proposal.
In addition, there are strong reasons for sending atomic clocks in space beyond searches for dark matter; a few such reasons
include spacecraft navigation, improved GPS technology, and highly-precise tests of General Relativity. Along these lines,
the atomic physics and particle physics community have recently worked together to understand how the study of atomic
systems in space could benefit fundamental science more broadly [4].
We propose that in the future, a network of atomic or nuclear clocks around the solar system could provide all of thesebenefits while simultaneously providing novel ways to discover dark matter.

22

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Research Highlights

5.3 Tensions in Cosmology and How We Infer
Them
Elisa Gouvea Mauricio FerreiraWith the increase of our theoretical knowledge but mostly with the improvement of the observations of our universe, mostnotably those of the afterglow of the hot early Universe called the cosmic microwave background (CMB), our understanding of cosmology has gone through a revolution in the past decades. We have nowadays the standard cosmologicalmodel (a.k.a ΛCDM - Λ cold dark matter), a parametrization capable of explaining a large part of the evolution of ouruniverse, its composition, and the structures we see today. This model is extremely successful observationally, having mostof its 6 parameters measured with a sub percent precision.

In order to resolve this confusion and determine the status of EDE to solve the Hubble tension, in collaboration with Laura
Herold and Eiichiro Komatsu, we explored this problem in a series of papers [4, 5, 6]. Using a complementary statistical1
method, the profile likelihood, we showed in [4] (with a follow up in [6]) that the discrepancy between previous analyses
came due to what is called prior volume effects or marginalization effects present in the standard statistical methods basedon Markov Chain Monte Carlo (MCMC) that biases the results obtained. With that, we could obtain a consistent confidence
interval for H0, see fig. 2, using a prior-free method and conclude that EDE indeed resolves the Hubble tension, being instatistical agreement with the SH0ES direct measurement at <1.7σ for CMB (Planck) and LSS (BOSS) data.

However, with the increase in the precision that we measure the parameters that describe our universe discrepancies haveappeared. Those are discrepancies between the values of cosmological parameters directly measured or predicted fromdifferent observational techniques that have become statistically significant with the latest data analyses. We call these
discrepancies cosmological tensions. These have been taking the attention of the cosmology community and are considered by some one of the most pressing problems in cosmology nowadays.
The most important and significant of these tensions is the “Hubble tension” (or H0 tension). Measurements of the Hubble
constant, H0, the present-day expansion rate of the universe, obtained via indirect measurements, which depend on theassumption of a cosmological model, yield systematically lower values of H0 than direct measurements, which do not or
weakly depend on the assumption of a cosmological model. The most significant tension is seen between the (indirect)
inference of H0 from CMB data of the Planck mission assuming the standard cosmological model (ΛCDM) [1], H0 = 67.4 ± 0.5
km/s/Mpc, and the (direct) local inference from Cepheid-calibrated Type Ia supernovae of the SH0ES project [2], H0 = 73. 0 ±1.0 km/s/Mpc, see Fig. 1. The statistical significance of the tension is currently 5σ!

and red shaded areas show the 1σ and 2σ constraint for H0 from SHOES [2] and Planck [1], respectively.

More than just for the case of EDE, our work called the attention and convinced the cosmology community that marginalization effects in MCMC are important and should be seriously taken into consideration in cosmological analysis. This canbe seen in the inclusion of this type of analysis or the use of profile likelihoods by a growing number of authors and intosome observational collaborations. As we are showing in some upcoming papers using different observational data anddata analyses, the method shown here is a necessary tool for the statistical analyses and data sets that are subject to marginalization effects.

Research Highlights

Despite the importance of this measurement, the origin of this discrepancy is still unknown. This could represent unknown
systematics in the measurement and analysis of these observations. Or this tension could hint at new physics beyond theΛCDM model.

Figure 2: Values of H0 obtained using profile likelihood and MCMC for the EDE model [6]. For comparison, the grayThis discussion and expertise is especially relevant for the upcoming surveys, like the Prime Focus Spectrograph, a collaboration led by IPMU, or stage 4 projects, where these statistical analyses are going to be much more intricate. Studying thesecosmological tension, but mainly applying this and other statistical tools in order to proper infer cosmological parameters
is one of the goals of my group at IPMU, together with my collaborators.

Figure 1: Value of the Hubble parameter measured over the years using direct measurements (blue) and indirect measurements from CMB experiments (black).

References[1] N. Aghanim et al. (Planck), Astron. Astrophys. 641, A6 (2020).
[2] Adam G. Riess et al., The Astrophysical Journal Letters, Volume 934, Number 1 (2022).
[3] V. Poulin, T. L. Smith, T. Karwal,.[arxiv: 2302.09032 [astro-ph.CO]].
[4] Laura Herold, Elisa G. M. Ferreira, and Eiichiro Komatsu, The Astrophysical Journal Letters 929 L16 (2022).
[5] Alexander Reeves, Laura Herold, Sunny Vagnozzi, Blake D. Sherwin, and Elisa G. M. Ferreira, Mon. Not. Roy. Astron. Soc.
520 (2023) 3688.
[6] Laura Herold and Elisa G. M. Ferreira, Phys. Rev. D 108, 043513 (2023).

There are proposals for beyond ΛCDM models to solve the H0 tension modifying either the early or the late evolution of theuniverse. One of the proposed models to alleviate the tension is early dark energy (EDE) (see [3] for a review). This model
has been classified as one of the most promising solutions to the H0 tension. In this model, the ΛCDM cosmology is extended
to include a dark energy-like component in the pre-recombination era, before the CMB, that boosts the expansion rate of
the universe before rapidly decaying. After its proposal, different authors performed separate analysis and there was not aconsensus in the literature on the role of EDE in solving the Hubble tension and whether EDE was favored by both CMB
and large-scale structure (LSS) data.
1

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Laura Herold won the Kippenhahn Prize 2023 for this article.
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Research Highlights

5.4 What Can We Do With Asian-Oceanian
Women in Mathematics?
Yukari Ito

If you see around the world, there are several associations for women in mathematics. For example, Association for Womenin Mathematics (AWM) is now more than 50 years old and it is a big power in mathematical society in the United States. Now
the president of American Mathematical Society (AMS) and the director of Mathematical Science Research Institute (MSRI,
will change the name to SL(Simons Laufer) Math) are women. But both of them said to me they still need AWM and theysaid it helps women in various situation.
There were 4 continental organizations for women in mathematics (See the map: Fig.1) and in 2022, August 1, a new association
for women in mathematics in Asia and Oceania was born and I
became a member of the executive committee. It is Asian-Oceanian Women in Mathematics (AOWM) with the following purpose and so on:

Continental Organizations for Women in Mathematics

EWM 1986
AWM 1971
AOWM 2022
AWMA 2013
CGD UMALCA 2020

Purpose Promote activities of all aspects of women in mathematics in Asia and Oceania, support research and career pursuit ofyoung women in particular.
Fig. 1: Continental Organizations for Women in Mathematics.
Activities Exchange information, strengthen communications
and networks, provide meeting opportunities and places as aforum, workshops, schools in special topics, training opportunities, prize for young women in mathematics, Webpage,mailing list, newsletter, and data base.
Membership Any women working or studying in mathematics at universities in Asia or Oceania. And men can be a member except for a member of the executive committee.
Let’s see the history before the birth. In 2020, Kyewon Koh Park and Soonyi Kang wrote an article on KWMS (Korean Womenin Mathematical Sciences) for AWM 50th Anniversary publication: Fifty Years of Women in Mathematics: Reminiscences, History, and Visions for the Future of AWM. Around the end of the article they wrote regarding an association for women mathematicians in Asia.
Then Marie-Francoise Roy who was a chair of CWM (Committee for Women in Mathematics under International Mathematical Union) showed strong interest and encouragement in building an association in the region and helped them to findpeople who will be members of Working Group.
The following 8 people from Asia and Oceania started the working group from December 2020 and had several meetings;
Motoko Kotani (Chair, Japan), Sanoli Gun (India), Le Thanh Nhan (Vietnam), Kyewon Koh Park (Korea), Polly Sy (Phillipines),
Dongmei Xiao (China), Bakhyt Alipova (Kazakhstan) and Catherine Greenhill (Australia). And all working group members
agreed to be AOWM members at the 2nd AO CWM ambassadors meeting on Feb. 25 2022.
Then AOWM Foundation Meeting was held on August 1, 2022. Total number of the members is 216 from 17 countries(contain male members). It contained 7 Australian, 6 Chinese, 54 Indian, 1 Indonesian, 2 Iranian, 34 Japanese, 2 Kazakhstan,
2 Malaysian, 4 from Nepal, 11 from New Zealand, 1 Pakistan, 12 Philippines, 60 South Korean, 6 from Sri Lanka, 9 fromThailand, 1 Uzbekistan, 1 from Vietnam.

It has just started and there are some rules. We will have general
meetings every two years and half of the EC members will be
replaced in two years. We have no funding at this moment andhave to think about our activities and future of AOWM. As the situation of women in mathematics in each country is different, wehave to help and encourage one another.
We had the first Inaugural Meeting of AOWM, on April 24-28,
2023, at ICTS, Bengaluru, India. ICTS is International Center for
Theoretical Sciences and has several actions and events for women in Mathematics and Physics and we can learn many thingsfrom them as a similar institute. (Fig. 3)[Credit: Sanoli Gun, Melissa Tacy, Polly Sy, Hyang-Sook Lee, Budi Nurani
Ruchjana, Yukari Ito, Dongmei Xiao, Bakhyt Alipova, Zohreh Mostaghim]

Fig. 2: Executive Committee Members of AOWM.

There are similar organization for women in mathematics in some countries in Asia and Oceania.
Though there are some Japanese members in
AOWM, we don’t have our own organization in
Japan. To make some network between female
mathematician and also students are very important to continue their studies and become researchers. Then I organized a conference “Women in
Mathematics” at RIMS, Kyoto University in September 2022 [1] and we heard reports on the activities[Credit: ICTS-TIFR]
of Association of Women in Mathematics (AWM),
Fig. 3: Inaugural Meeting of the Asian-Oceanian Women in Mathematics.
European Women in Mathematics (EWM) andKorean Women in Mathematical Sciences (KWMS)
and I made a report as RIMS Kokyuroku[2]. Moreover, we will have a conference“The world of Mathematical Sciences” at Kavli IPMU in August 2023 [3] and makenew network with individual webpages. It will also help young scientists to get a
new job in academia.

Research Highlights

I am a mathematician and my research area is algebraic geometry. I meet only one or two women when I attend a conference on algebraic geometry in Japan. This situation has been the same since I was a graduate student. The percentage ofwomen in Mathematical Society of Japan is 6 and those of female professors in the top 10 universities in Japan is almost 1.
It is not the same in other countries and there may be gender bias to be a mathematician in Japan.

References[1] Conference “Women in Mathematics” at RIMS, Kyoto University 2022. https://lab-search.app.labbase.jp/women-in-mathematics/[2] RIMS Kokyuroku 2248. https://www.kurims.kyoto-u.ac.jp/~kyodo/kokyuroku/
contents/2248.html[3] Conference “The World of Mathematical Sciences” at Kavli IPMU, 2023. https://indico.ipmu.jp/event/424/[Credit: Emily Nakajima]Fig. 4: Poster of “Women in Mathematics” at RIMS.

The first members of the executive committee are as follows: (See pictures of EC: Fig. 2)
President : Sanoli Gun (India), Vice President : Melissa Tacy (New Zealand) and Polly Sy (Philippines) and Secretary: HyangSook Lee (Korea). The Ordinary EC members are Budi Nurani Ruchjana (Indonesia), Yukari Ito (Japan), Dongmei Xiao (China),
Bakhyt Alipova (Kazakhstan) and Zohreh Mostaghim (Iran).

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Research Highlights

5.5 From Space to Ground Applications
Miho Katsuragawa

For ground-based experiments, we have developed various imaging systems using cadmium telluride double-sided strip
detectors (CdTe-DSDs). The CdTe-DSD, which was developed for the Hitomi satellite (ASTRO-H) launched in 2016 [3], has ahigh energy resolution by using technique of Schottky diode electrodes [1,2]. In accelerator experiments, we detectedmuon X-rays from light elements, which had been difficult to image, by introducing CdTe-DSD, and succeeded in theworld’s first two-dimensional imaging [4]. In addition, we have been working on establishing a three-dimensional imaging
technique for muon X-rays [5].
In recent years, our group has focused on applications in nuclear medicine. In nuclear medicine, radiopharmaceuticals areused to diagnose and treat diseases, and the visualization of X-rays and gamma rays from inside the body using SPECT(Single Photon Emission Computed Tomography) and PET (Positron Emission Tomography) devices is also an important
method of molecular imaging [6]. Our group is a team of astrophysicists and medical researchers working together to solve
problems in the field of nuclear medicine by applying space observation techniques to nuclear medicine.
Our group has been developing imaging systems that combine CdTe-DSD with various collimators for different purposes.
One such system is an ultra-high spatial resolution SPECT system that aims to visualize the local distribution of drugs andprobes accumulated inside a tumor [7]. It is composed of CdTe-DSD and pinhole optics to achieve sub-mm spatial resolution and can identify structures of about 250 μm. In addition, we have established a new analytical method and succeededin multi-probe imaging by applying the analysis technique of astronomical observation data (Fig. 1) [8]. In molecular imaging, images are obtained by selecting a specified energy range (energy window) for each nuclide. Since X-rays in theenergy range of several tens to several hundred keV are scattered in the body and by the collimator, the scattered X-rays
become background components and cause image degradation. In the case of simultaneous imaging of multiple nuclides,
the signal from other non-targeted nuclides cannot be separated only by specifying the energy window, and the distribution of the drug may be detected in places where the drug is not originally present. We have solved these problems byquantification by spectral fitting and image correction.

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A

B

Spectra

IPMU imager

20

30

40

keV

C

D

Conventional

30

40
keV

Fig. 1 (A) Energy spectra obtained by our imaging system and a conventional system. Dotted lines shown with the spectrum of our imager mean fitting models.
(B) A three-color coronal image obtained with our imaging system using three radionuclides. (green: I-125 in thyroid, red: In-111 in lymph node, blue: Tc-99m
in lymph node) (C) A coronal image in the I-125 energy band taken with conventional system. (D) Reconstructed coronal image in the I-125 energy band
(26-29 keV) obtained with our imaging system. Figures were extracted from [8].

References[1]������������������������������������������������������������������������������������������������������������������������
 ����������������������������������������������������������������������������������������������������������������������
T.��������������������������������������������������������������������������������������������������������������������
 �������������������������������������������������������������������������������������������������������������������
Takahashi, et al., “High-resolution schottky CdTe diode for hard X-ray and gamma-ray astronomy”, Nucl Instrum Methods Phys Res A, 436, 111, 1999.
[2] S. Watanabe, et al.,“High energy resolution hard X-ray and gamma-ray imager using CdTe diode devices”, IEEE Trans Nucl
Sci, 56, 777, 2009.
[3] G. Sato, et al., “The Si/CdTe semiconductor camera of the ASTRO-H Hard X-ray Imager (HXI)”, Nucl Instrum Methods Phys
Res A, 831, 235, 2016.
[4] M. Katsuragawa, et al., “A compact imaging system with a CdTe double-sided strip detector for non-destructive analysis
using negative muonic X-rays”, Nucl Instrum Methods Phys Res A, 912, 140, 2018.
[5] IH. Chiu, et al., “Non-destructive 3D imaging method using muonic X-rays and a CdTe double-sided strip detector”, Sci
Rep, 12, 5261, 2022.
[6] S. R. Cherry, et al., “Physics in nuclear medicine”, ELSEVIER, Philadelphia, 2012.
[7] S. Takeda, et al., “A high-resolution CdTe imaging detector with multi-pinhole optics for in-vivo molecular imaging”, Nucl
Instrum Methods Phys Res A, 912, 57, 2018.
[8] A. Yagishita, et al., “Simultaneous visualization of multiple radionuclides in vivo”, Nat Biomed Eng, 6, 640, 2022.

Kavli IPMU Annual Report 2022

Research Highlights

In observational high-energy astrophysics, the physical mechanisms of high-energy objects are being studied by analyzingenergy spectra and images obtained from observations of X-rays and gamma rays emitted from the objects. Observational
instruments are required to have high performance in terms of energy resolution, spatial resolution, and sensitivity, andthey must also meet stringent environmental conditions, such as being small and light enough to be installed on satellites.
However, it is not only in space that X-rays and gamma rays hold the key to solving problems. Hard X-ray and gamma-ray
imaging are increasingly recognized as valuable techniques in various fields of accelerator experiments and medical
research. In the study of developing X-ray/gamma-ray semiconductor detectors for astronomical observation, our grouplearned that the superior capabilities of our instruments could also be used in these various fields on the ground.

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Research Highlights

5.6 The Case of the Missing Protocluster
Shadow
Khee-Gan Lee
Galaxy protoclusters, the precursors to modern-day galaxy clusters, are moderately dense agglomerations of young galaxies from the universe’s early epochs, spanning up to tens of megaparsecs. As they evolve, these protoclusters merge to form
the colossal gravitationally bound entities known as galaxy clusters, which we observe in the present-day Universe. Matureclusters house a rich mix of galaxies, dark matter, and baryonic hot gas. The cluster gas, which encompasses up to 10% of
the cosmic baryon budget, is known as intra-cluster medium (ICM) and emits X-rays due to its temperatures exceeding
7
T>10 K. The hot ICM, which emits X-rays and, has been shaped by gas shock heating from gravitational collapse and various feedback processes from its resident galaxies.

Last year, Kavli IPMU postdoctoral researcher Metin Ata (now at Stockholm University) employed a novel method known asconstrained simulations on galaxy spectroscopic data, unearthing several new 2.0<z<2.5 galaxy protoclusters within thewell-examined COSMOS field. Many of these protoclusters coincide with the IGM gas map from my CLAMATO tomographic survey. Notably, one of the protoclusters at z=2.3, named‘COSTCO-I,’lacks the characteristic hydrogen Lyman-alphaabsorption ‘shadow’ seen in other protoclusters (Figure 1).

Figure 1: Color scale indicates the observed hydrogen absorption in vicinity of the COSTCO-I galaxy protocluster (top panel), compared with the expected absorption given the presence of the protocluster, assuming it behaves like the rest of the IGM at this epoch. Strong hydrogen absorption isshown in red while weak absorption is shown in blue, and intermediate absorption is denoted as
green or yellow colors. The black dots indicate member galaxies through which the protocluster
was first identified. At the position of COSTCO-I (with its center marked as a star in both panels),
astronomers found that the observed hydrogen absorption is much lower than expected, suggesting that some large-scale heating mechanism is operating within this structure.

Research Highlights

However, at redshifts of z>2 (more than 10 billion years ago), the gas within galaxy protoclusters has not yet collapsed and4is believed to be largely similar to other regions of the Universe, existing in a relatively cool state (T∼10 K) in photo-ionization equilibrium with the ambient ultraviolet (UV) radiation. While the expansive intergalactic medium (IGM) is almost
entirely ionized at this epoch, trace amounts of hydrogen remain neutral, revealing their presence through Lyman-alphaabsorption in the restframe UV radiation. Historically, this Lyman-alpha ‘forest’ has been studied using the bright background light from quasars along isolated 1-dimensional lines-of-sight. Over the past decade, I have pioneered the technique of “Intergalactic medium (IGM) tomography,” employing the world’s most powerful telescopes to study the Lymanalpha Forest in dense groupings of faint background galaxies. IGM tomography enables us to map the large-scale 3D gas
distribution during the era of galaxy protoclusters. As galaxy protoclusters are overdense structures, they often exhibit
pronounced Lyman-alpha forest absorption, reminiscent of a dense grove of trees casting a solid shadow against the sun.
Multiple research groups, including mine, have detected this absorption signal from several galaxy protoclusters at z∼2.

Subsequently, UTokyo graduate student Chenze Dong undertook a comprehensive analysis of COSTCO-I. Ata’s methodology permitted us to trace the underlying large-scale structure. Consequently, Dong was able to calculate the expected
Lyman-alpha absorption from the overdensity represented by COSTCO-I, operating under the assumption that the protocluster gas aligns with the photoionized equilibrium typical of the IGM during those times. By considering uncertainties inprotocluster mass, morphology, and pixel noise, Dong determined it was highly improbable (p<0.0026) for the protocluster
gas to behave like the global IGM. This fascinating finding was later published in the Astrophysical Journal Letters (Dong etal. 2023, 945, 2, L28).
Given that the gas around COSTCO-I is transparent in the Lyman-alpha forest, it indicates the gas has been heated to theextent that the residual neutral hydrogen within the protocluster has become collisionally ionized (Figure 2). One theory
suggests this structure might have already experienced gravitational collapse, shock-heating the gas on vast scales, akin to
the galaxy clusters of today. However, preliminary investigations into hydrodynamical simulations propose that such a
process is highly unlikely by the early epoch (z∼2) represented by COSTCO-I, when most structures are still transitioning.
Thus, it appears that feedback from supermassive black holes within the protoclusters, possibly in the form of intense radiation from active quasars or large kinetic jets forming radio bubbles on megaparsec scales, is a more probable explanation.
Research into analogous structures will significantly influence our understanding of the feedback processes from active
galactic nuclei (AGN). Next year, the new Prime Focus Spectrograph on the Subaru Telescope will be operational, augmenting the available samples of galaxy protoclusters at z>2 by a significant factor. This will enable us to make statistically robust
claims about the role of AGN in heating protocluster gas and the vast IGM as the Universe progresses.

Figure 2: A hydrodynamical simulations depicts the scenario of large-scale heating around a galaxy protocluster.
This is believed to be a similar scenario to that observed in the COSTCO-I protocluster. The yellow area inthe center of the picture represents a huge, hot gas blob spanning several Megaparsecs. The blue color
indicates cooler gas tracing the large-scale IGM, connecting the outer regions of the protocluster andfilaments connecting to the cosmic web. (Simulation credit: The THREE HUNDRED Collaboration)

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Research Highlights

5.7 The Classical Equations of Motion of Quantised Gauge Theories
Tom Melia
The Maxwell and Einstein equations occupy a special place in the minds and hearts of theoretical physicists. They are thejewels in the crown of classical physics — a canon of thought that for hundreds of years formed our scientific understandingof the universe we live in.

Maxwell: ∂μ F μν = J ν

Einstien: G μν = T μν

References[1] David E. Kaplan, Tom Melia, Surjeet Rajendran, The Classical Equations of Motion of Quantised Gauge Theories, Part I:
General Relativity, arXiv 2305:01798[2] David E. Kaplan, Tom Melia, Surjeet Rajendran, The Classical Equations of Motion of Quantised Gauge Theories, Part II:
Electromagnetism, arXiv 2307:09475

It is interesting then that these classical theories were written down at the turn of the 20th century, right at the point in time
when our classical beliefs about the universe were starting to crumble. New experiments were starting to show that the
microscopic world behaved very differently. A few years after Einstein published his theory of general relativity, Schrödinger wrote down his famous equation,i∂| Ψ⟩ = H | Ψ⟩ ,∂twhere H is the Hamiltonian of the physical system, and |Ψ⟩ is the quantum mechanical wavefunction. This ushered in a newera of physics and interpretation of the universe, and the framework of quantum mechanics has provided a description of
every experiment we have performed to date.

Research Highlights

Quantum mechanics is more fundamental than classical mechanics. The latter exists only as a particular limit of the former:
classical equations of motion follow from the quantum theory by taking expectation values of the corresponding operator
equations (this is known as Ehrenfest’s theorem).
However, for gauge theories, such as electromagnetism and general relativity, not all of the classical equations of motion
can be obtained from the quantum theory in this way. This is because some of the ‘equations of motion’ are in fact constraint equations that do not dictate how the degrees of freedom (the photon, the graviton) evolve in time. These constraint
equations are Gauss’ law in electromagnetism, and are the time-time and time-space components of Einstein’s equations
in general relativity that give rise e.g. to the first Friedmann equation in cosmology.
So how do the classical constraint equations arise from the limit of the quantum theory? In the standard approach toquantising these theories, they come about from a choice of initial quantum state. In electromagnetism one can show that
if the quantum state satisfies Gauss’ law initially, it will satisfy Gauss’ law at all times; similarly in cosmology regarding the firstFriedmann equation.
My work with David E. Kaplan and Surjeet Rajendran has questioned this ‘choice’. What if the initial quantum state of theuniverse was actually different to this? The quantum theory is still perfectly well-defined: the Hamiltonian of electromagnetism or general relativity can evolve these different choices of quantum state. However, the classical constraint equations— Gauss’ law and the first Friedmann equation — get an effective additional contribution that captures the ‘violation’ produced by the chosen state. This looks like an additional fixed background charge in Gauss’ law, and background dust or
cold dark matter in the Friedmann equation. We called these ‘shadow’ contributions, because they are not real charges ormasses: they are a result of the chosen configuration of initial electric and gravitational fields.
The real charges and masses in the universe would respond to these shadow charges and masses, leading to observablesignatures. For the case of general relativity, it is striking that we do indeed observe a dark matter component in the classicalequations of motion of the universe. This warrants further study to determine how much of the dark matter we see could
just be a choice of the initial conditions of the state of gravitational field.

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Research Highlights

5.8 A New Probe of Inflationary Gravitational
Waves: Cross-Correlations of Lensed Primary
CMB B-modes with Large-Scale Structure
Toshiya Namikawa

Soon, measurements of the high-precision “B-modes,” a twisting pattern in a polarization map, will become essential to
explore fundamental issues in cosmology. For example, B-modes provide a unique avenue to explore the early universe,
where inflation stretched quantum fluctuations and seeded cosmological structures. Inflation predicts the generation of abackground of gravitational waves, which is not yet confirmed. The inflationary gravitational waves (IGWs) impart a characteristic B-mode pattern in the CMB polarization map. Thus, detecting such B-modes on large angular scales allows us tounveil the physics of the very early universe. Current and future CMB experiments seek to constrain the tensor-to-scalarratio, r, which characterizes the IGW amplitudes more tightly, targeting specific predictions of inflation theories and restricting the parameter space to identify if and how inflation happened.
Precise B-mode data also provide a powerful means of revealing physics in the late-time universe through gravitational
lensing of CMB; as the CMB photons travel through the universe, they are gravitationally deflected by the mass distributionof the large-scale structure (LSS) through which they pass. CMB lensing thus creates B-modes at small angular scales. CMB
lensing probes the history of the LSS directly and is sensitive to the properties of neutrinos, which affect the growth of the
LSS. Analysis of the precise B-mode data to extract lensing signals is thus a powerful probe of the unknown mass of neutrinos.
The IGW B-modes provide a new way to probe the early universe, but there are two key challenges we must overcome inongoing and future CMB experiments. One is the lensing- induced B-modes. The B-modes from lensing must not be
confused with those arising from IGWs. The lensing contaminants in B-modes already limit the detection of IGWs. Thus, totest new inflation regimes and for the full success of future experiments, we need to estimate the lensing B- mode contribution and subtract it from observed B-modes. The other, more complicated issue is the contaminants from the Galactic
foregrounds. In CMB measurements, radiation from Galactic foregrounds dominates on large-angular scales of anisotropies. We must remove IGW B-modes from Galactic foregrounds, but its complete understanding is challenging. For
example, in 2014, the BICEP2 team claimed detection of the IGW B-modes after careful treatment of the Galactic foregrounds based on the best knowledge of the foregrounds at that time. However, unfortunately, it turned out to be just the
Galactic foreground B-modes.

In FY2022, I developed and proposed a new IGW probe to overcome the Galactic foreground issue. The key idea to distinguish between the IGW B-modes and Galactic foregrounds is that the former is distorted by gravitational lensing of thelarge-scale structure, while the latter is not (see Fig.1). The former is correlated with the tracer of the mass distribution in the
LSS, such as galaxy distribution. On the other hand, the latter does not correlate with the LSS tracers. The estimator isequivalent to measuring a three-point function of two CMB B-modes and an LSS tracer. With this fact, I found that the newobservable, the correlation between IGW B-modes and mass distribution, will be sensitive to the IGW amplitudes.
We forecasted the expected one-sigma constraints on the tensor-to-scalar ratio, r, albeit with a simplistic foreground treatment, and found constraints of σr ~ 0.007 from the correlation of CMB- S4-Deep B-mode lensing and LSST galaxies,
σr ~ 0.005 from the correlation of CMB-S4-Deep B- mode lensing and CMB-S4-Deep CMB lensing, and σr ~ 0.01 from thecorrelation of LiteBIRD B-mode lensing and CMB-S4-Wide lensing. Because this probe is inherently non-Gaussian, simple
Gaussian foregrounds will not produce any biases in the measurement of r. While a detailed investigation of non-Gaussian
foreground contamination for different cross-correlations will be essential, this observable has the potential to be a powerful probe of IGWs, complementary to standard methods for constraining r.
The estimate of σr obtained above is derived by assuming experimental configurations not optimized for the proposed
method. In the experimental configurations assumed in the above analysis, CMB experiments are designed to observe
polarization in multiple frequencies to mitigate the Galactic foreground biases in the B-mode auto power spectrum. In our
proposed method, however, we do not need many frequencies to mitigate the Galactic foregrounds. There is, thus, room
to improve the constraint on r with our method.
The results were recently published in https://arxiv.org/abs/2304.10315.

Research Highlights

During FY2022, one of my significant achievements was to develop and propose a new method to probe cosmic inflation
by measurement of cosmic microwave background (CMB) polarization, as detailed below.

Fig.1: The important contributions to the observed B-modes. This figure is made based on the images provided by the BICEP collaboration (http ://bicepkeck.org/visuals.html) and by the ESA Planck project (https://www.cosmos.esa.int/web/planck).

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Research Highlights

5.9 Probing the Generalized Symmetry Structureof Quantum Field Theory
Emily Margaret Nardoni

Credit: Noel Tovia Matoff

Quantum Field Theory (QFT) is the heart of modern theoretical physics, supplying the language in which we understandthe interactions of fundamental particles and model the phases of matter. It is a ubiquitous feature that the degrees of
freedom in a QFT reorganize in highly nontrivial ways between high and low energies under renormalization group flow,
and that the most interesting physical phenomena are emergent in regimes where the constituent fields are stronglyinteracting. The central challenge of 21st century QFT is to learn how to extract universal features and dynamics of such
emergent phenomena in strong coupling regimes where standard perturbative techniques fail.

In the last several years the very concept of symmetry has been revolutionized, with wide reaching consequences acrosstheoretical physics. The idea is that the familiar notion of symmetry as a set of operators that commute with the Hamiltonion can be extended; operators can form more general algebras than groups (so that they are “non-invertible”), and be
defined on different-dimension submanifolds of spacetime and thus imply transformation rules for lines and other extended operators (generating “higher-form” symmetries)—see [1] for a recent review and more detailed references. The key
point of view is that the symmetry operators depend topologically on these submanifolds, with fusion rules governed ingeneral by (higher) fusion categories. These generalized symmetries lead to new conservation rules, new constraints on
dynamics, and new ways of distinguishing phases. We are developing the vocabulary of this new language, and there is
1
much still to learn!
My recent research has focused on developing modern tools for characterizing the generalized symmetry structure of QFTs.
One such toolset are ’t Hooft anomalies, renormalization group invariant quantities that characterize the detailed data ofsymmetries of QFTs. ’t Hooft anomalies are extremely important for constraining the low-energy phases of gauge theories
since they must match between high and low energies; any proposed phase must match all ’t Hooft anomalies of all symmetries (whether or not we’ve been clever enough to uncover them all!), and so for example any nontrivial anomaly forbids
a trivial vacuum.

(a)	A topological operator defined on a p- dimensional submanifold (blue, depicted for p = 1) of
the d + 1 dimensional bulk SymTFT can be
attached to a p-dimensional operator (green)in the d-dimensional boundary, which generates the boundary generalized symmetry.

(b)	The anomaly of the boundary symmetry is probed by link invariants of the attached bulk operators, computed by their correlation
functions. The dimensions of the operators and type of correlation
function depends on which anomaly coefficients α are being
probed.

Figure 1: Probing ’t Hooft anomalies from the SymTFT.

PSU (N ) adjoint QCD to rule out the existence of a trivially gapped vacuum, and also to anomaly matching in N = 1 superYang-Mills. This is an exciting time to build on these stepping stones and attack the problem of how to fully utilize andextract information from the SymTFT.

Research Highlights

I approach this problem in my research through the lens of symmetry. Symmetry has deep implications for the study of
Quantum Field Theory, first and foremost as an indispensable principle for distinguishing physical systems—the celebrated
Landau paradigm has taught us that phases of matter are labeled by how they represent their symmetries, so that e.g. theeight light pseudoscalar mesons arise as Nambu-Goldstone bosons of approximate chiral symmetry breaking in QCD.
Symmetries are so powerful because they furnish invariant characterizations of QFTs; they imply constraints on renormalization group flows, are fixed under dualities, and constrain observables often to the point of computability.

References[1] C. Cordova, T. Dumitrescu, K. Intriligator & S-H. Shao, e-print: 2205.09545.
[2] F. Apruzzi, F. Bonetti, I. Garcia Etxebarria, S. Hosseini & S. Schafer-Nameki, Commun.Math.Phys. 402, 1 (2023).
[3] J. Kaidi, K. Ohmori & Y. Zheng, e-print: 2209.11062.
[4] J. Kaidi, E. Nardoni, G. Zafrir & Y. Zheng, e-print: 2301.07112.

The state of the art for capturing generalized (higher form, non-invertible) symmetries and their ’t Hooft anomalies is ad + 1 dimensional topological QFT known as the Symmetry Topological Field Theory (SymTFT), on whose boundary thed-dimensional QFT of interest resides as a sort of edge mode. A generalization of anomaly inflow from the bulk SymTFT
encodes the generalized symmetries of the boundary QFT, in ways that are actively being explored and understood (withmany outstanding questions especially for d > 2!) [2, 3].
In work with both fellow and former IPMU members, we have explained how the SymTFT captures key data about the ’t
Hooft anomalies of non-invertible symmetries for QFTs in general dimensions, and applied it to constrain the phases of 2dand 4d gauge theories [4]. The key insight is that the topological generalized symmetry operators in the boundary QFT
arise from operators in the bulk SymTFT, and that the braiding of these bulk operators serves as a diagnostic of the boundary ’t Hooft anomalies (see Figure 1). We showed that this perspective is powerful in probing the anomalies of non-invertible
symmetries, for which a general characterization in d > 2 is not fully developed. By identifying anomalous non-invertible
symmetries in 4d gauge theories, we were then able to constrain their low-energy phases; for example, we applied this to1

The starring role of symmetry in physics goes back at least to Einstein’s early 20th century work on relativity, while the role of (e.g.) non-invertible symmetries has only recently begun to be appreciated.

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Research Highlights

5.10 Filaments of the Cosmic Web Shine in the
X-raysHideki Tanimura
filaments through the distortion of the CMB spectrum. In addition, my other studies using the gravitational lensing effecton the CMB successfully derived the total matter density in the filaments, which proved that the filaments are actual gravitationally bound structures. These results will also be improved by the future CMB surveys such as Simons Observartory
and CMB-S4. Because the CMB data has a better sensitivity at higher redshift than X-ray, a combination of these probes will
clarify the fundamental question of how the hot gas in the cosmic web co-evolve with dark matter across time.

To trace the large-scale structure of the Universe observationally, galaxies, formed in regions where dark matter is concentrated, are the most prominent luminous baryonic component and millions of galaxies have been observed in several galaxy surveys. However, galaxies only comprise less than 10% of baryonic matter and the rest of > 90% is in the form of
baryonic gas. The baryons have been observed in stars, cold interstellar medium, residual Lyα forest gas, ionized oxygen,broad Lyα absorbers, and hot gas in clusters of galaxies, but it has been found that the observed baryons only account fori~70% of the expected; the remainder has yet to be identified and constitutes so-called missing baryons . There has been
extensive research to discover the missing baryons, although hydrodynamical simulations predicted that most of the missing baryons might be located in the cosmic web filaments in the form of warm hot intergalactic medium (WHIM) with
5
7
temperatures ranging between 10 and 10 K and over-densities between 10 and 100. It explains that light emitted by the
missing baryons is too faint to observe, and a novel technique and/or higher-quality data are required to detect the faintsignature.

v

In my further study, I took advantage of the most recent X-ray survey data from SRG/eROSITA . The X-ray data with a higher
2
sensitivity enabled me to detect the X-ray signals with only 460 filaments within the first 140 deg survey released by thevi
SRG/eROSITA collaboration and even allowed more precise constraints on the hot plasma’s physical states . In addition, its
higher energy resolution allowed to confirm that the detected X-ray signal is undoubtedly associated with a thermal emission from the hot plasma in the cosmic filaments, not from stars or galaxies. Moreover, I have forecast its future improvement using the full-sky SRG/eROSTA, and it predicts that the origin of the thermal emission should be answered using thefull SRG/eROSTA data released in coming years, and the future planned large X-ray observatories.
These findings confirmed my earlier analyses based on indirect detections of hot gas in the cosmic web through its effectvii
on the cosmic microwave background (CMB), so called Sunyaev Zel’dovich effect . It provided the gas pressure inside theiShull, J. M., Smith, B. D., & Danforth, C. W. 2012, ApJ, 759, 23
H Tanimura, N Aghanim, A Kolodzig, M Douspis, N Malavasi, 2020, A&A, 643, L2
iii
Piffaretti, R., Arnaud, M., Pratt, G. W., Pointecouteau, E., & Melin, J.-B. 2011, A&A, 534, A109
iv
Malavasi, N., Aghanim, N., Douspis, M., Tanimura, H., & Bonjean, V. 2020, A&A, 642, A19v
	Predehl, P., Andritschke, R., Böhringer, H., et al. 2010, in Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, Vol. 7732,
Space Telescopes and Instrumentation 2010: Ultraviolet to Gamma Ray, 77320Uvi
H Tanimura, N Aghanim, M Douspis, N Malavasi, 2022, A&A, 667, A161vii
H Tanimura, N Aghanim, V Bonjean, N Malavasi, M Douspis, 2020, A&A, 637, A41@Tanimura, Aghanim (CNRS) & eROSITA
Figure1: SRG/eROSITA map overlaid with the filaments identified with the SDSS galaxies.

(data-model)/err Normalized counts s–1 KeV–1

Therefore, I have led a research project to detect this missing baryon and identify the physical states with Nabila Aghanim,a researcher at the Institut d’Astrophysique Spatiale (CNRS/Université Paris-Saclay). In this project, I have detected, for theii
first time, the X-ray emission from the hot gas in filaments . This detection has been achieved by my new statistical approachwith a combination of multi-wavelength data. In detail, I have studied a spatial correlation of the X-ray signals from theiii
ROSAT survey data at the locations of approximately 15 000 large-scale cosmic filaments identified with the SDSS galaxy
iv
data . In addition, I have derived the density and temperature of the hot gas through the X-ray spectral analysis. This result
has provided clear evidence of hot gas in the cosmic web and has paved the way for more detailed studies, using better
quality data, to test the evolution of gas in the filamentary structure along with the structure formation in the Universe.

Research Highlights

The structure formation in the Universe has been widely studied with numerical simulations. The cosmological simulations
suggest that matter in the Universe is not distributed randomly, but rather distributed in the form of a complex network
throughout the Universe, called the cosmic web. In the cosmic web, clusters of galaxies are located at the intersections offilamentary structures and most of the cosmic volume is occupied by low-density voids. The formation of this cosmic web
can be explained by the gravitational attraction of dark matter, but because dark matter does not emit light nor interact
with ordinary matter (so-called baryon), the distribution and evolution of the cosmic web cannot be directly observed andmust be inferred.

Data
Model (APEC)

10 – 4

10 –5

10 – 6
2.5
0.0
–2.5

0.5

1.0

Energy (keV)

2.0

Figure2: X-ray spectrum measured with the SRG/eROSITA map at the positions of filaments.

ii

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Research Highlights

5.11 MUSSES2020J: The Earliest Discovery of a
Fast Blue Ultraluminous Transient at Redshift
1.063
Naoki Yasuda

The fast blue ultraluminous transient (FBUT) is a new transient type confirmed several years ago and subsequently investigated by several transient survey projects recently. The majority of FBUTs reach peak brightness of -17 to -20 mag in blue
optical wavelengths which is comparable with the most luminous supernovae while their timescales are significantly
shorter.
To figure out the nature of various transient phenomena, an international transient survey project called“MUltiband Subaru
Survey for Early-phase Supernovae” (MUSSES), led by Ji-an Jiang, a former Kavli Institute for the Physics and Mathematics of
the Universe (Kavli IPMU) Project Researcher (currently Project Research Staff at the University of Science and Technology ofChina (USTC)) attempt to catch various fast-evolving transients within one day of their occurrence, using the most powerfulsurvey facility in the world, the Hyper Suprime-Cam (HSC) mounted on the 8.2-m Subaru telescope.

By carrying out consecutive Subaru/HSC observations in December 2020, 20 fast-evolving transients have been discovered, and one of them, MUSSES2020J (AT 2020afay), caught our attention.
MUSSES2020J was discovered with very low brightness on December 11 in 2020, and its brightness
showed significant brightening during our observation. More surprisingly, the fast light curve evolution
and very high redshift of the transient confirmed byfollow-up observations (by the Astrophysical ResearchConsortium 3.5 m telescope and the 3.6 m Devasthal
Optical Telescope) indicate that the brightness of
MUSSES2020J was about 50 times higher than normal
supernovae, while the rising phase was much shorter
than those of normal supernovae, which indeed showhigh similarity to a recently discovered peculiar transient, AT 2018cow, which is an representative FBUT. So
far only a handful of them have been discovered, andwe had never seen one soon after its occurrence dueto their extremely fast evolution. Thanks to the highcadence survey mode and the excellent performanceof Subaru/HSC, we were able to perfectly catch thisamazing phenomenon at very early stage for the firsttime. The early multiband light-curve data bring someunique information to understand the origin of theseamazing transients.

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Kavli IPMU Annual Report 2022

A very fast-rising lightcurve of MUSSES2020J was obtained during the Subaru/HSC survey, with a g-band brightness
increase of a factor of about 23 in 5 days (observer frame). Follow-up observations show the brightness of MUSSES2020J
kept increasing in the next 4 days after the last Subaru/HSC observation, indicating rise time as short as ~10 days in theobserver frame.
Given the shortest projected distance and the lowest photometric redshift (also the highest brightness) among all galaxies
within 10 arcseconds from MUSSES2020J, we identified the nearest galaxy as the host galaxy of MUSSES2020J. We haveexecuted a spectroscopic observation of the host galaxy at the Gemini-North observatory, the redshift of the host galaxy
has been determined as 1.063.
MUSSES2020J is located near the center of a normal low-mass galaxy at redshift 1.063. This suggests a possible connection
between the energy source of MUSSES2020J and the central part of the host galaxy. The color behaivior and physicalproperties derived from the early multiband light curve suggest that previously proposed scenarios such as the winddriven scenario and the SN-CSM (circumstellar material) can at least qualitatively explain the general features of
MUSSES2020J. In the case of wind-driven TDE (tidal disruption event) scenario, where a star is tidally disrupted by as massive black hole, the mass of central black hole is consistent with 1 x 10^6 solar mass as expected from the M_{BH} - M_*correlation drived for nearby galaxies. More detailed theoretical work focusing on the multiband light-curve fit is required
to answer the origin of this extreme transient.

Research Highlights

The universe is full of energetic transient phenomena, astronomical events that occur over a short period of time. For
example, most massive stars end their lives by exploding spectacularly, known as a supernova, a major type of transient. In
order to understand the origin of these transient phenomena, various time-domain surveys have been carried out in thepast few decades. As more and more transients have been discovered, researchers began noticing some new transient
types in recent years.

For details, please refer to our paper (Ji-an Jiang et al. ApJL, 933, L36, 2022).

Figure 1: The schematic light curves of MUSSES2020J and other typical energetictransients (green and orange points denote the stages that MUSSES2020J
was observed by the 8.2-m Subaru and follow-up telescopes, respectively).
HSC g, r, and i composite multicolor thumbnail image of the host galaxy isshown in the bottom-right corner. A blue cross indicates the location of
MUSSES2020J, which is almost at the nucleus of the host galaxy.

Kavli IPMU Annual Report 2022

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Credit: Kavli IPMU

Hiraku Nakajima elected President of the International Mathematical Union

Credit: Yukari Ito

National Academy of Sciences elected Takaaki Kajita as new international
memberThe University of Tokyo’s Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU) Senior Fellow,
and Institute for Cosmic Ray Research Professor, Takaaki Kajita was elected as a member of the US National Academyof Sciences.
The National Academy of Sciences is a private, non-profit society of distinguished scholars. Established in 1863, scientists are elected by their peers to membership in the NAS for outstanding contributions to research. Currently, theAcademy includes 2512 members, 517 international members. Of these members, 190, including Kajita, havereceived a Nobel Prize.

Hirosi Ooguri received Science Lectureship Award
Hirosi Ooguri, Director of the Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU)and theFred Kavli Professor of Theoretical Physics and Mathematics at California Institute of Technology, was named therecipient of the 2022 Science Lectureship Award by Chiba University, Japan.
The Science Lectureship Award recognizes researchers with outstanding achievements in sciences. The award has
been given every year since 2005 with the exception of 2011 due to the Great Japan Earthquake and 2020 due tothe COVID-19 pandemic. Recipients are invited to give lectures at the Faculty of Sciences of Chiba University.
Credit: Hirosi Ooguri

Yukari Ito selected as new member of The Association of Academies andSocieties of Sciences in Asia’s Women in Science and Engineering Committee

Credit: Yukari Ito

Professor Yukari Ito of the Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU), The Universityof Tokyo, was selected as a new member of the Special Committee Women in Science and Engineering (WISE),
under The Association of Academies and Societies of Sciences in Asia (AASSA).
AASSA was set up in 2012 to achieve a society in Asia and Australasia in which science and technology play a majorrole in the development of the region, where scientists and technologists discuss and provide advice on issues
related to science and technology, research and development, and the application of technology for socio-economic development. AASSA currently has members in 30 countries and regions, and 32 organizations, including theScience Council of Japan.

Kavli IPMU Senior Fellow Eiichiro Komatsu Received Nishina Memorial Prize
Max Planck Institute for Astrophysics Director and Kavli Institute for the Physics and Mathematics of the Universe(Kavli IPMU) Senior Fellow Eiichiro Komatsu was awarded the 2022 Nishina Memorial Prize, it was announced on
November 10 by the Nishina Memorial Foundation.
The Nishina Memorial Prize commemorates the achievements of the late Dr. Yoshio Nishina and is an honor given
to relatively young researchers who have made outstanding research achievements in atomic and sub-atomic physics and their applications. It is the oldest and most prestigious physics award in Japan.
Credit: Thomson Reuters

Yukari Ito selected as executive committee member of the Asia-Oceania
Women in Mathematics
Professor Yukari Ito of the Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU), The Universityof Tokyo, was selected as a member of the newly established Asia-Oceania Women in Mathematics, under the International Mathematics Union (IMU).
The AOWM was established after the Committee for Women in Mathematics (CWM) under the IMU had received acall for its development this year. The CWM has established similar groups in the past, including the European
Women in Mathematics in 1971, the Association for Women in Mathematics in 1983, the African Women in Mathematics in 2013, and the Comisión de Género -Unión Matemática de América Latina y el Caribe in 2020, but this willbe the first group to be active in the Asia-Oceania region.

Hiraku Nakajima, Professor at the Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU), waselected the President of the International Mathematical Union (IMU), it was announced at the IMU general assemblyon July 4, 2022.
The IMU was established in 1920, but was later dissolved, then re-established in 1951 when ten countries became
members, including Japan. It is an international non-governmental and non-profit scientific organization, with the
purpose of promoting international cooperation in mathematics. Currently, more than 80 countries are members.
The IMU is famous for awarding scientific prizes deemed to be the highest distinction in mathematics, including the
Fields Medals.
Nakajima has served on several IMU-related committees since 2006. He will take over as IMU President from 2023
and serve for four years.

Masahito Yamazaki awarded the 19th JSPS Prize
Masahito Yamazaki, Professor at Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU), wasselected to share the 19th JSPS Prize, it was announced by the Japan Society for the Promotion of Science (JSPS) on
December 15.
The JSPS Prize was established in 2004 and recognizes young researchers under the age of 45 who have made significant contributions to the humanities, social sciences, or natural sciences. This year, 25 awardees were selected.
Yamazaki has been recognized for his work on integrable models using supersymmetric quiver gauge theories andthe 4-dimensional Chern-Simons theory.

Awards & Honors

6

AWARDS & HONORSAwards & Honors

Credit: Kavli IPMU

Hitoshi Murayama named Chair of P5 Committee

Hiromi Yokoyama awarded the Tokyo Academy of Physics Award

Hitoshi Murayama, Professor at the Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU) was
selected as the Chair of the Particle Physics Project Prioritization Panel (P5) in the US, it was announced by the US
Department of Energy and the National Science Foundation in November 2022.
The P5 recommends priorities in particle physics research projects for the next ten years, and reports to the HighEnergy Physics Advisory Panel that in turn advises the High-Energy Physics of the US Department of Energy Officeof Science, and the Division of Physics at the National Science Foundation.

Hiromi Yokoyama, Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU) Professor and Deputy Director, was awarded the 5th Tokyo Academy of Physics Award (Tokyo University of Science).
The Tokyo Academy of Physics Award (Tokyo University of Science) was established in 2018, and recognizes past
graduates or past employees of Tokyo University of Science who have made significant contributions to science,and raised awareness about the university.

Credit: Hitoshi Murayama
Credit: Tokyo University of Science

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Invited talks given by the Kavli IPMU researchers (Selected 12 of 198)

Conference Title

Attendees(from abroad)

Presenter

Kyiv Formula and Related Aspects

85
(14)

Elisa Gouvea Mauricio
Ferreira

Ultra-light dark matter: the light andfuzzy side of dark matter

SynCRETism 2022
June 25, 2022

Geometric Representation Theory

279
(244)

Takeo Higuchi

Recent Results from Belle and Belle II

International Conference on Kaon Physics 2022
(KAON2022)
September 15,2022

Jia Liu

Cosmology with Massive Neutrinos

Unsolved Problems in Astrophysics andCosmology Workshop
December 5, 2022

Shigeki Matsumoto

Decay of the Mediator Particle at theThreshold

IAS Program on High Energy Physics
February 16, 2023

Hitoshi Murayama

Theory vision: the questions before us

Seattle Snowmass 2022
July 17, 2022

Hiraku Nakajima

Coulomb branches of 3d N=4 SUSY
gauge theories and bow varieties

Workshop on Interactions between
Representation Theory, Combinatorics, andGeometry
December 27-29, 2022

Toshiya Namikawa

A quick overview of delensing for largescale B-modes

Key Challenges in Galaxy & CMB Lensing
July 8, 2022

145
(35)

Hirosi Ooguri

Summary Talk:Perspectives andProspects

Strings 2022
July 22, 2022

March 2 - 3, 2023, Media Hall, The University of Tokyo Kashiwa Campus, Chiba

155
(67)

Satoshi Shirai

On Detection of Axion Dark Matter

FY2022 “What Is Dark Matter? - Comprehensive Study of the Huge Discovery Space in
Dark Matter”

Asian-European-Institutes Workshop for BSM
November 17, 2022

158
(14)

Mark Vagins

A Gadolinium-Loaded SuperKamiokande

Neutrino 2022
June 2, 2022

Masahito Yamazaki

Elliptic Hypergeometric Integrals in
Mathematics and Physics

Dynamics of SCFTs and Special Functions
April 19, 2022

Octagon and ELSI segment for AI

HCC15 (Human Choice and Digital by Default:
Autonomy vs Digital Determination: 15th IFIP
International Conference on Human Choice
and Computers, HCC 2022)
September 9, 2022

Date, Place

April 5-6, 2022 [Online]

June 27 - July 2, 2022 [Online]

Hyper-Kamiokande Collaboration Meeting

138
(83)

Non-linear Aspects of Cosmological Gravitational Waves

32
(19)

HirosiFest @ Kavli IPMU

191
(39)

June 20 - July 2, 2022 [Online]

July 18 - 22, 2022, Lecture Hall, Kavli IPMU

October 20 - 21, 2022, Lecture Hall, Kavli IPMU

What the Heck Happens When the Universe Boils?

63
(40)

Current Trends in Categorically Approach to Algebraic and Symplectic Geometry

19(4)

Geometry and Automorphicity of Supersymmetric Partitions (GASP)
February 13 - 17, 2023, Lecture Hall, Kavli IPMU

69
(44)

Gauge Theory, Moduli Spaces and Representation Theory -In Honor of the 60th Birthdayof Hiraku Nakajima-

135
(42)

December 5 - 9, 2022, Lecture Hall, Kavli IPMU
February 4 - 6, 2023, Lecture Hall, Kavli IPMU

February 27 - March 3, 2023, Lecture Hall, Kavli IPMUInterdisciplinary Science Conference in Okinawa (Isco 2023) -Physics and Mathematics
Meet Medical ScienceFebruary 27 - March 3, 2023, OIST, Okinawa

PFS Collaboration Meeting

March 7 - 9, 2023, Media Hall, The University of Tokyo Kashiwa Campus, Chiba

Hiromi Yokoyama

44

8

CONFERENCE PRESENTATIONSAND SEMINAR TALKS

Kavli IPMU Annual Report 2022

Presentation title

Conference name and date

Kavli IPMU Annual Report 2022

Conference Presentations and Seminar Talks

7

CONFERENCES

45

9

OUTREACH AND
PUBLIC RELATIONS

46

Date

Venue

Number ofParticipants

26th Kavli IPMU × ICRR Joint Public Lecture "The Mystery of the
Faraway Galaxy and Universe"

April 9, 2022

Amuser Kashiwa &Online421

15th Anniversary Symposium: World Premier International ResearchCenter Initiative (WPI) “Kavli IPMU’s 15 Years of Science and Future
Prospects”

April 24, 2022

Yasuda Auditorium,
The University ofTokyo & Online

1,022

Kavli IPMU presents film screening "M.C. Escher: Journey to Infinity"

June 12, 2022

Online427

Science Café in English "Universe" 2022 "The Dark Side of the
Universe: How We Know It's There and How We Might Find It"

July 10, 2022

Online45

Science Café in English "Universe" 2022 "Strange Telescopes:
Universes Are Made by Machines"

September 24,
2022

Online40

Open Campus Kashiwa 2022

October 22-23,
2022

Online3,287

7th Of Course I Love Physics: Careers for Girls in Physics

November 19,
2022

Online43

8th Kavli IPMU / ELSI / IRCN Joint Public Lecture: "A Question of
Origins"November 23,
2022

Online508

11th Annual WPI Science Symposium: "The Infinite Possibilities
Opened by Science"

November 23,
2022

Ito Hall,
The University ofTokyo & Online

284

Kavli IPMU × ICRR Joint Online Public Lecture: "The Forefront of the
Exploration for Dark Matter"

December 11,
2022

Online407

Event Title

Kavli IPMU Annual Report 2022

April 2022–March 2023

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 2022

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