arXiv subjects

Masahiro Kawasaki

Publications and source records attributed to Masahiro Kawasaki.

238 records · Page 14Linked to original sources

arXiv2000

Double Inflation in Supergravity and the Boomerang Observations

One of the biggest mystery of the recent observation of cosmic microwave background anisotropies by the boomerang team is insignificance of the second acoustic peak in the angular power spectrum. It is very difficult to explain such a low amplitude without assuming the higher baryon density than predicted by the Big Bang Nucleosynthesis (BBN). Employing the double inflation model in supergravity, we show that the density fluctuations produced by this inflation model can produce a sufficient low second acoustic peak with the standard value of the baryon density from BBN. It is shown that these density fluctuations are also consistent with the observations of cluster abundances and galaxy distributions.

astro-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↗

arXiv1996

Solving the Crisis in Big-Bang Nucleosynthesis by the Radiative Decay of an Exotic Particle

We discuss a new mechanism which can solve the crisis in standard big-bang nucleosynthesis. A long-lived particle $X$ ($10^4 sec \lesssim τ_X \lesssim 10^6 sec$) which decays into photon(s) will induce cascade photons, and destroy significant amounts of D and $^3$He without destroying $^4$He or too much $^7$Li. We numerically investigate this process and derive a constraint on the properties of $X$ such that the theoretical values of the primordial light-element abundances agree with observation. We also present some candidates for the unstable particle $X$.

hep-ph↗

arXiv1994

Collapse of Axionic Domain Wall and Axion Emission

We examine the collapse of an axion domain wall bounded by an axionic string. It is found that the collapse proceeds quickly and axion domain walls disappear. However axions are emitted in the collapse and its energy density increases during radiation dominated era and contributes significantly to the present mass density of the universe. In particular the axion emitted from the wall can account for the dark matter in the universe for $F_a\gsim 10^{10}\GeV$.

astro-ph↗