arXiv subjects

Izumi Joichi

Publications and source records attributed to Izumi Joichi.

4 recordsLinked to original sources

arXiv2001

On the Power Spectrum Density of Gamma Ray Bursts

Gamma ray bursts (GRBs) are known to have short-time variability and power-law behavior with the index -1.67 in the power spectrum density. Reanalyzing the expanded data, we have found a) the power-law comes from the global profile of the burst and not from the self-similar shots nor rapid fluctuations in the luminosity profile. b) The power indices vary from burst to burst and the value -1.67 is given simply as the mean value of the distribution; there is no systematic correlation among GRBs to yield the power law.

astro-ph↗

arXiv2000

Galaxy Distributions and Tsallis Statistical Mechanics

Large-scale astrophysical systems are non-extensive due to their long-range force of gravity. Here we show an approach toward the statistical mechanics of such self-gravitating systems (SGS). This is a generalization of the standard statistical mechanics based on the new definition of entropy; Tsallis statistical mechanics. Developing the composition of entropy and the generalized Euler relation, we investigate the galaxy distributions in count-in-cell method. This is applied to the data of CfA II South redshift survey.

astro-ph↗

arXiv1994

Heavy Polonyi Field as a Solution of the Polonyi Problem

We study properties of the Polonyi field in the renormalizable hidden sector in supergravity models. It is shown that radiative corrections induce a sizable coupling of the Polonyi field to gravitinos as well as raise its mass to an intermediate scale. We find it serves a solution of the Polonyi problem and show that the gravitino abundance produced by the Polonyi decay is not large. It is also pointed out that soft supersymmetry breaking terms induced by this hidden sector are very restricted.

hep-ph↗

arXiv1994

Stability of Gauge Hierarchy in Einstein Supergravity

In supersymmetric grand unified theories, the gauge hierarchy achieved by a fine-tuning in the superpotential can be violated in the presence of soft breaking terms. We examine this problem in Einstein supergravity with hidden-sector supersymmetry breaking. We show that the hierarchy is preserved if couplings of the hidden sector to visible-sector fields in the superpotential satisfy a certain requirement.

hep-ph↗