Leptogenesis in Inflationary Universe

TL;DR

This paper explores leptogenesis in the early universe through non-thermal decays of heavy Majorana neutrinos produced during inflaton decay, demonstrating successful baryon asymmetry generation across various SUSY inflation models at low reheating temperatures.

Contribution

It provides a comprehensive analysis of leptogenesis in different SUSY inflation scenarios, showing viability at low reheating temperatures compatible with gravitino constraints.

Findings

Leptogenesis can produce sufficient baryon asymmetry in multiple SUSY inflation models.

Successful leptogenesis occurs even at reheating temperatures as low as 10^6 GeV.

The results are consistent with big-bang nucleosynthesis and gravitino abundance constraints.

Abstract

We investigate the leptogenesis via decays of heavy Majorana neutrinos which are produced non-thermally in inflaton decays. We make a comprehensive study on the leptogenesis assuming various supersymmetric (SUSY) models for hybrid, new and topological inflations. For an estimation of the lepton asymmetry we adopt the Froggatt-Nielsen mechanism for mass matrices of quarks and leptons. We find that all of these models are successful to produce the lepton asymmetry enough to explain the baryon number in the present universe. Here we impose low reheating temperatures such as $T_R \lesssim 10^8$ GeV in order to suppress the abundance of gravitinos not to conflict with the big-bang nucleosynthesis. Furthermore, we find that the leptogenesis works very well even with $T_R \simeq 10^{6}$ GeV in the SUSY hybrid or new inflation model. It is known that such a reheating temperature is low enough to suppress the abundance of gravitinos of mass $m_{3/2} \simeq 100$ GeV--1 TeV. Thus, the leptogenesis is fully consistent with the big-bang nucleosynthesis in a wide region of the gravitino mass.