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 2018

10/4 Suzuki
Searching for Dark Matter with Paleo-Detectors
Sebastian Baum, Andrzej K. Drukier, Katherine Freese, Maciej Górski, Patrick Stengel

10/11 Hasegawa
Cosmic strings and primordial black holes
Alexander Vilenkin, Yuri Levin, Andrei Gruzinov

10/18 Otani
Dark energy as a remnant of inflation and electroweak symmetry breaking
Konstantinos Dimopoulos, Tommi Markkanen

10/25 Ibe
Constraints on symmetry from holography
Daniel Harlow, Hirosi Ooguri

11/1 Hayashi
Dwarf spheroidal J-factors without priors: A likelihood-based analysis for indirect dark matter searches
A. Chiappo, J. Cohen-Tanugi, J. Conrad, L. E. Strigari, B. Anderson, M.A. Sanchez-Conde
Dwarf spheroidal J-factors without priors: approximate likelihoods for generalised NFW profiles
A. Chiappo, J. Cohen-Tanugi, J. Conrad, L. E. Strigari

11/15 Ando
Single-Field Consistency relation and δN-Formalism
Ali Akbar Abolhasani, Misao Sasaki

11/22 Inomata
The Primordial Black Hole Dark Matter - LISA Serendipity
N. Bartolo, V. De Luca, G. Franciolini, M. Peloso, A. Riotto
Testing Primordial Black Holes as Dark Matter through LISA
N. Bartolo, V. De Luca, G. Franciolini, M. Peloso, D. Racco, A. Riotto

11/29 Kawasaki
Weighing the Solar Axion
Theopisti Dafni, Ciaran A. J. O'Hare, Biljana Lakić, Javier Galán, Francisco J. Iguaz, Igor G. Irastorza, Krešimir Jakovčić, Gloria Luzón, Javier Redondo, Elisa Ruiz Chóliz

12/6 Obata
Searching for Axion Dark Matter with Birefringent Cavities
Hongwan Liu, Brodi D. Elwood, Matthew Evans, Jesse Thaler

12/13 Sonomoto
Can Light Dark Matter Solve the Core-Cusp Problem?
Heling Deng, Mark P. Hertzberg, Mohammad Hossein Namjoo, Ali Masoumi

12/20 Nakano
Exploring High Multiplicity Amplitudes: The QM Analogue of the Spontaneously Broken Case
Joerg Jaeckel, Sebastian Schenk

1/31 Nakatsuka
Adiabatic Electroweak Baryogenesis Driven by an Axion-like Particle
Kwang Sik Jeong, Tae Hyun Jung, Chang Sub Shin

2/7 Kobayashi
Radio Signals from Axion Dark Matter Conversion in Neutron Star Magnetospheres
Anson Hook, Yonatan Kahn, Benjamin R. Safdi, Zhiquan Sun

2/14 Nagai
Cosmology With a Very Light Lμ−Lτ Gauge Boson
Miguel Escudero, Dan Hooper, Gordan Krnjaic, Mathias Pierre

2/21 Murai
Audible Axions
Camila S. Machado, Wolfram Ratzinger, Pedro Schwaller, Ben A. Stefanek

3/1 Sato
Primordial Black Holes With Multi-Modal Mass Spectra
Bernard Carr, Florian Kuhnel


In Colloquium, we talk about our research.

Second semester in 2018

10/5 Obata

10/19 Hayashi

11/2 Inomata

Interim report for doctoral thesis

Interim report for doctoral thesis

Interim report for master's thesis

Interim report for master's thesis

1/25 Nakano

2/1 Sonomoto

2/15 Ando

3/1 Nagai



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).