arXiv subjects

Shinta Kasuya

Publications and source records attributed to Shinta Kasuya.

41 records · Page 3Linked to original sources

arXiv2002

Adiabatic density perturbations and matter generation from the MSSM

We propose that the inflaton is coupled to ordinary matter only gravitationally and that it decays into a completely hidden sector. In this scenario both baryonic and dark matter originate from the decay of a flat direction of the minimal supersymmetric standard model (MSSM), which is shown to generate the desired adiabatic perturbation spectrum via the curvaton mechanism. The requirement that the energy density along the flat direction dominates over the inflaton decay products fixes the flat direction almost uniquely. The present residual energy density in the hidden sector is typically shown to be small.

hep-ph↗

arXiv2002

Surface reheating as a new paradigm

In this talk we briefly review the standard idea of reheating and then present a new paradigm of reheating the Universe through surface evaporation.

hep-ph↗

arXiv2002

Inflatonic Solitons In Running Mass Inflation

The inflaton condensate associated with a global symmetry can fragment into quasistable Q balls, provided the inflaton oscillations give rise to an effective equation of state with negative pressure. We study chaotic inflation with a running inflaton mass and show that, depending on the sign of the radiative mass correction, the process of fragmentation into inflatonic Q balls can actually take place even though no net charge exists. If the main decay channel of the Q ball is to fermions, the universe will be reheated slowly via surface evaporation.

hep-ph↗

arXiv2002

Reheating as a surface effect

We describe a new mechanism for reheating the Universe through evaporation of a surface charge of a fragmented inflaton condensate. We show that for a range of Yukawa coupling of the inflaton to the matter sector evaporation gives rise to a much smaller reheat temperature compared to the standard perturbative decay. As a consequence, reheating through a surface effect could solve the gravitino and moduli over production problem in inflationary models without fine tuning the Yukawa sector.

hep-ph↗

arXiv1997

Restriction to Parametric Resonant Decay after Inflation

We study parametric resonant decay of inflaton field with emphasis on its physical meaning. We show that the parametric resonance is indeed an induced process, which means that the more numbers of produced particles, the more inflaton field decays. We also consider the dissipative effects of produced particles and find that the dissipation reduces the resonant decay rate of inflaton field.

hep-ph↗