arXiv subjects

M. Peloso

Publications and source records attributed to M. Peloso.

21 records · Page 2Linked to original sources

arXiv1999

Can unstable relics save pure Cold Dark Matter?

The standard CDM model fails to describe the power spectrum of fluctuations since it gives too much power at small scales. Among other possible improvements, it has been suggested that an agreement with observations can be achieved with the addition of a late decaying particle, through the injection of non-thermal radiation and the consequent increase of the horizon length at the equivalence time. We analyze the possibility of implementing this idea in some extensions of the electroweak standard model, discussing the cosmological and astrophysical bounds to which these schemes are subject.

hep-ph↗

arXiv1999

Leptogenesis via preheating

Leptogenesis constitues a very simple scenario to achieve the baryon asymmetry that we observe today. It requires only the presence of right handed neutrinos (which arise very naturally in many extensions of the Standard Model) and depends crucially on the mechanism responsible for their production. In particular, when their mass exceeds the inflaton mass (10^13 GeV in chaotic inflation) only non perturbative production can occur. It is shown here that non perturbative production of fermions in an expanding Universe is a very efficient mechanism up to masses of order of (10^17 - 10^18) GeV, and that it can be easily applied to solve the baryon asymmetry problem.

hep-ph↗

arXiv1999

Production of Massive Fermions at Preheating and Leptogenesis

We present a complete computation of the inflaton decay into very massive fermions during preheating. We show that heavy fermions are produced very efficiently up to masses of order 10^{17}-10^{18} GeV; the accessible mass range is thus even broader than the one for heavy bosons. We apply our findings to the leptogenesis scenario, proposing a new version of it, in which the massive right-handed neutrinos, responsible for the generation of the baryon asymmetry, are produced during preheating. We also discuss other production mechanisms of right-handed neutrinos in the early Universe, identifying the neutrino mass parameters for which the observed baryon asymmetry is reproduced.

hep-ph↗