Publications by Shintaro Eijima

Freeze-in and freeze-out generation of lepton asymmetries after baryogenesis in the nu MSM

Mikhail Chapochnikov, Shintaro Eijima, Inar Timiryasov

The nu MSM an extension of the Standard Model by three relatively light singlet Majorana fermions N-1,N-2,N-3 allows for the generation of lepton asymmetry which is several orders of magnitude larger than the observed baryon asymmetry of the Universe. The ...

IOP Publishing Ltd2022

Parameter space of baryogenesis in the nu MSM

Mikhail Chapochnikov, Shintaro Eijima, Inar Timiryasov

The Standard Model accompanied with two right-handed neutrinos with masses below the weak scale can explain the observed baryon asymmetry of the Universe. Moreover, this model is at least partially testable in the forthcoming experiments such as NA62, SHiP ...

Springer Nature2019

Freeze-out of baryon number in low-scale leptogenesis

Mikhail Chapochnikov, Shintaro Eijima, Inar Timiryasov

Low-scale leptogenesis provides an economic and testable description of the origin of the baryon asymmetry of the Universe. In this scenario, the baryon asymmetry of the Universe is reprocessed from the lepton asymmetry by electroweak sphaleron processes. ...

Iop Publishing Ltd2017

Fermion number violating effects in low scale leptogenesis

Mikhail Chapochnikov, Shintaro Eijima

The existence of baryon asymmetry and dark matter in the Universe may be related to CP-violating reactions of three heavy neutral leptons (HNLs) with masses well below the Fermi scale. The dynamical description of the lepton asymmetry generation, which is ...

Elsevier2017

Initial condition for baryogenesis via neutrino oscillation

Shintaro Eijima

We consider a baryogenesis scenario via the oscillation of right-handed neutrinos with Majorana masses of the order of GeV, which are also responsible for neutrino masses by the seesaw mechanism. We study how the initial condition alters the prediction of ...

American Physical Society2017

On neutrinoless double beta decay in the nu MSM

Shintaro Eijima

We consider the neutrinoless double beta (0 nu beta beta) decay in the nu MSM, in which three right-handed neutrinos with masses below the electroweak scale are additionally introduced to the Standard Model. In this model there appear three heavy neutral l ...

Elsevier2016

Neutrinoless double beta decay and low scale leptogenesis

Marco Drewes, Shintaro Eijima

The extension of the Standard Model by right handed neutrinos with masses in the GeV range can simultaneously explain the observed neutrino masses via the seesaw mechanism and the baryon asymmetry of the universe via leptogenesis. It has previously been cl ...

Elsevier2016

A facility to search for hidden particles at the CERN SPS: the SHiP physics case

Mikhail Chapochnikov, Anurag Tripathi, Alexey Boyarsky, Oleg Ruchayskiy, Lesya Shchutska, Marco Drewes, Shintaro Eijima, Kyrylo Bondarenko

This paper describes the physics case for a new fixed target facility at CERN SPS. The SHiP (search for hidden particles) experiment is intended to hunt for new physics in the largely unexplored domain of very weakly interacting particles with masses below ...

Institute of Physics2016

Lepton universality in the nu MSM

Shintaro Eijima

We consider the nu MSM which is an extension of the Standard Model by three right-handed neutrinos with masses below the electroweak scale, in which the origins of neutrino masses, dark matter, and baryon asymmetry of the universe are simultaneously explai ...

Elsevier Science Bv2015