Ryo Nagai

J-GLOBAL         Last updated: Oct 22, 2018 at 10:36
Ryo Nagai
Tohoku University

Research Areas


Academic & Professional Experience

Apr 2017
Tohoku University, Particle Theory and Cosmological Group


Apr 2008
Mar 2012
Tohoku University

Published Papers

Ryo Nagai, Fuminobu Takahashi, Norimi Yokozaki
Phys.Lett. B784 (2018) 37-42      May 2018
The absence of supersymmetric particles at the weak scale is a puzzle if
supersymmetry solves the gauge hierarchy problem. We show that, if the
right-handed neutrino masses arise from hidden gaugino condensation via
GUT-suppressed operators, succe...
Tomohiro Abe, Junji Hisano, Ryo Nagai
   Dec 2017
We derive a Wilson coefficient of a CP-violating purely gluonic dimension-6
operator called the Weinberg operator (Tex) generated by a scalar and
two fermions at the two-loop level. We do not specify the representation of
SU(3)Tex for t...
Norimi Yokozaki, Ryo Nagai
   Nov 2017
We provide a simple solution to the Tex-Tex problem in the
"Tex-invariant direct gauge mediation model". With the solution, the Higgsino
and gluino are predicted to be light as TexGeV and
TexTeV, respectively. Tho...
Tomohiro Abe, Ryo Nagai
Phys. Rev. D 95, 075022 (2017)      Jul 2016
We investigate decay modes of spin-1 heavy vector bosons (Tex) from the
viewpoint of perturbative unitarity in a model-independent manner. Perturbative
unitarity requires some relations among couplings. The relations are called
unitarity sum rule...
Tomohiro Abe, Ryo Nagai, Shohei Okawa, Masaharu Tanabashi
Phys. Rev. D 92, 055016 (2015)      Jul 2015
We investigate Tex interpretations for the ATLAS 2 TeV diboson anomalies.
The roles of the unitarity sum rules, which ensure the perturbativity of the
longitudinal vector boson scattering amplitudes, are emphasized. We find the
unitarity sum rule...


Junji Hisano, Ryo Nagai, Natsumi Nagata
   Aug 2018
We study the phenomenology of singlet Dirac fermion dark matter in the
simplified models where the dark matter interacts with the Standard Model
particles at loop-level with the help of either colored or non-colored
mediators. We especially focus ...
Ryo Nagai
   Apr 2015
We study perturbative unitarity and electroweak oblique corrections in the
electroweak symmetry breaking models including an arbitrary number of neutral
Higgs bosons. Requiring the perturbative unitarity of the high energy
scattering amplitudes of...

Conference Activities & Talks

Leptogenesis explains little hierarchy
Ryo Nagai
14 Sep 2018   
Geometry and Symmetry in Generalized Higgs Sectors
Ryo Nagai
Workshop on Multi-Higgs Models 2018   4 Sep 2018   
Model independent evaluation of the Wilson coefficient of the Weinberg operator in QCD
Ryo Nagai
RCNP Workshop on Fundamental Physics using Neutrons and Atoms   18 Aug 2018   
Symmetry and Geometry of Generalized Higgs Sectors
Ryo Nagai
6 Aug 2018   
Leptogenesis [Invited]
Ryo Nagai
International symposium neutrino frontiers   15 Jul 2018   

Association Memberships