136 research outputs found
Non-thermal leptogenesis and baryon asymmetry in different neutrino mass models
In the present work we study non-thermal leptogenesis and baryon asymmetry in the universe in different neutrino mass models discussed recently. For each model we obtain a formula relating the reheating temperature after inflation to the inflaton mass. It is shown that all but four cases are excluded and that in the cases which survive the inflaton mass and the reheating temperature after inflation are bounded from below and from above
Temperature dependence of absorption in photorefractive iron-doped lithium niobate crystals
We present experimental data showing a significant dependence of light absorption on temperature in photorefractive LiNbO3:Fe crystals. The results are successfully explained by assuming that the widths of the Fe2+ absorption bands in the visible and in the infrared spectral region depend on temperature. The findings are of relevance for thermal fixing of holograms. Furthermore, a temperature-induced increase of the infrared absorption is promising for improved infrared recording
Black hole shadow of a rotating polytropic black hole by the Newman--Janis algorithm without complexification
In this work, starting from a spherically symmetric polytropic black hole, a
rotating solution is obtained by following the Newman--Janis algorithm without
complexification. Besides studying the horizon, the static conditions and
causality issues of the rotating solution, we obtain and discuss the shape of
its shadow. Some other physical features as the Hawking temperature and
emission rate of the rotating polytropic black hole solution are also
discussed.Comment: 9 pages, 2 figures, some references adde
Novel charged black hole solutions of Born-Infeld type: General properties, Smarr formula and Quasinormal frequencies
We investigate two novel models of charged black holes in the framework of
non-linear electrodynamics of Born-Infeld type. In particular, starting from
two concrete Lagrangian densities, the corresponding metric potentials, the
electric field, the Smarr formula and finally, the (scalar) quasinormal modes
are computed for each model. Our findings show that although the models look
very similar, their quasinormal spectra are characterized by certain
differences.Comment: 18 pages, 7 figures, 3 tables, to be published in Annals of Physic
Gravitino dark matter in brane-world cosmology
The gravitino dark matter hypothesis in the brane cosmology is studied. The
theoretical framework is the CMSSM for particle physics and RS II brane model
for gravity. It is found that the gravitino can play the role of dark matter in
the universe and we determine what the gravitino mass should be for different
values of the five-dimensional Planck mass. An upper bound is obtained for the
latter.Comment: Improved version with minor corrections, to appear in JCA
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