# ICRR THEORY GROUP

The University of Tokyo

## A B O U T   U S

We are working on solving theoretical problems of physics in the Institute for Cosmic Ray Research (ICRR) in the Kashiwa campus of the Unviersity of Tokyo. In paticular, we concentrate on two interesting fields, Cosmology and Particle Phenomenology. In Cosmology, we are trying to reveal misteries of the early universe. In Particle Phenomenology, we are searching the more fundamental law of nature. Both of them focus on the extremely early history, about 1 second from the beginning of the universe.

## R E C E N T

2022-09-20
publishment
"Asymmetric Mediator in Scotogenic Model"
Kento Asai, Yuhei Sakai, Joe Sato, Yasutaka Takanishi, Masato Yamanaka
2022-09-19
publishment
"Isotropic cosmic birefringence from early dark energy"
Eiichiro Komatsu, Kai Murai, Toshiya Namikawa, Fumihiro Naokawa
2022-07-06
publishment
"Revisiting sterile neutrino dark matter in gauged $U(1)_{B-L}$ model"
Shintaro Eijima, Osamu Seto, Takashi Shimomura
2022-06-28
publishment
"Chiral $Z^\prime$ in FASER, FASER2, DUNE, and ILC beam dump experiments"
Kento Asai, Arindam Das, Jinmian Li, Takaaki Nomura, Osamu Seto

## C O S M O L O G Y

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.

### P A R T I C L E P H E N O M E N O L O G Y

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.

## A C C E S S

#### A d d r e s s

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

#### D i r e c t i o n s

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).