The University of Tokyo

ICRR Theory Group

about us

We are a group of physicists working on theoretical Cosmology and Particle Physics. In paticular, we focus on Particle Cosmology and Particle Phenomenology.

  • Particle Cosmology
    In Particle Cosmology, we investigate the interplay between Particle Physics and Cosmology during the early history of the universe. For example, many physicists consider that the universe underwent an extremely rapid exponential expansion (inflationary epoch) and the inflationary epoch can be described by Particle Physics. Recently, the results of Cosmic Microwave Background(CMB) observations have been shedding the light on some aspects of the inflationary epoch. The future observations, such as DECIGO and LiteBIRD, are expected to reveal the whole picture of the inflationary epoch.
  • Particle Phenomenology
    In Particle Phonomenology, we make new physics models beyond the Standard Model and investigate how the new models can be tested through experiments and observations. Although the Standard Model can explain some phenomena in Particle Physics, there are some problems in the Standard Model, such as "Hierarchy problem" and "Strong CP problem". On-going and future accelerator experiments and cosmic observations are expected to give us some hints of the new physics beyond the Standard Model.


Email addresses are followed by

The list of former members is here.


In our group, we have a Journal Club every Thursday and a Colloquium every other Friday.

Former seminars are here.

Journal Club

In Journal Club, we introduce recent papers.

Second semester in 2017

10/5 Yamaguchi
New solutions for non-Abelian cosmic strings
Mark Hindmarsh, Kari Rummukainen, David J. Weir

10/12 K.Suzuki
Attractive vs. repulsive interactions in the Bose-Einstein condensation dynamics of relativistic field theories
J. Berges, K. Boguslavski, A. Chatrchyan, J. Jaeckel

10/19 Sonomoto
Axion detection via Topological Casimir Effect
ChunJun Cao, Ariel Zhitnitsky

10/26 Hong
The Equation of State and Duration to Radiation Domination After Inflation
Kaloian D. Lozanov, Mustafa A. Amin
Self-resonance after inflation: oscillons, transients and radiation domination
Kaloian D. Lozanov, Mustafa A. Amin

11/2 Hayakawa
How to simulate global cosmic strings with large string tension
Vincent B. Klaer, Guy D. Moore
The dark-matter axion mass
Vincent B. Klaer, Guy D. Moore

11/9 Ando
Limits on primordial black holes from μ distortions in cosmic microwave background
Tomohiro Nakama, Bernard Carr, Joseph Silk

11/16 M.Suzuki
Probing axions with neutron star inspirals and other stellar processes
Anson Hook, Junwu Huang

11/30 Hayakawa
Interim report for doctoral dissertation

12/7 Hong
Interim report for doctoral dissertation

12/14 Nakano
Electrophilic dark matter with dark photon: from DAMPE to direct detection
Pei-Hong Gu, Xiao-Gang He
Interpretations of the DAMPE electron data
Qiang Yuan et al.

12/21 Shoji
Self-Destructing Dark Matter
Yuval Grossman, Roni Harnik, Ofri Telem, Yue Zhang

1/18 Inomata
No LIGO MACHO: Primordial Black Holes, Dark Matter and Gravitational Lensing of Type Ia Supernovae
Miguel Zumalacarregui, Uros Seljak
LIGO Lo(g)Normal MACHO: Primordial Black Holes survive SN lensing constraints
Juan Garcia-Bellido, Sebastien Clesse, Pierre Fleury

1/25 Kawasaki
Primordial Black Holes from Inflaton Fragmentation into Oscillons
Eric Cotner, Alexander Kusenko, Volodymyr Takhistov
Primordial deuterium abundance at z=2.504 towards Q1009+2956
E. O. Zavarygin, J. K. Webb, S. Riemer-Sørensen, V. Dumont

2/1 Ibe
Resonant absorption of bosonic dark matter in molecules
Asimina Arvanitaki, Savas Dimopoulos, Ken Van Tilburg
Neutron Star Cooling via Axion Emission by Nucleon-Nucleon Axion Bremsstrahlung
Avik Paul, Debasish Majumdar, Kamakshya Prasad Modak

2/8 Hasegawa
Axion-Like Particles and Recent Observations of the Cosmic Infrared Background Radiation
Kazunori Kohri, Hideo Kodama
Can decaying particle explain cosmic infrared background excess?
Kazunori Kohri, Takeo Moroi, Kazunori Nakayama

2/15 Kobayashi
Asymmetric dark matter: residual annihilations and self-interactions
Iason Baldes, Marco Cirelli, Paolo Panci, Kalliopi Petraki, Filippo Sala, Marco Taoso

2/22 Otani
Quintessential Inflation with α-attractors
Konstantinos Dimopoulos, Charlotte Owen

3/1 Nakatsuka
Hidden universality in the merger rate distribution in the primordial black hole scenario
Bence Kocsis, Teruaki Suyama, Takahiro Tanaka, Shuichiro Yokoyama


In Colloquium, we talk about our research.

Second semester in 2017

10/6 Hasegawa

10/20 Alex

11/10 Shoji

12/8 Sonomoto, Yamaguchi
Interim report for master's thesis

12/15 Ando, K.Suzuki
Interim report for master's thesis

1/26 Nakano

2/9 M.Suzuki

3/2 Inomata



University of Tokyo, ICRR,5-1-5 Kashiwanoha,Kashiwa, 277-8582 Japan


Get off at Kashiwanoha Campus Station of Tsukuba Express (TX) train.
Walk to the University of Tokyo, Kashiwa Campus (25 min) or take a bus/taxi (5min).