Effects of reheating on leptogenesis

Abstract

We study the evolution of a cosmological baryon asymmetry in leptogenesis when the right-handed neutrinos are produced in inflaton decays. By performing a detailed numerical study over a broad range of inflaton-neutrino couplings we show that the resulting asymmetry can be larger by two orders of magnitude or more than in thermal leptogenesis, if the reheating temperature T RH is of the same order as the right-handed neutrino mass M 1 . Hence, the lower limit on the baryogenesis temperature obtained in thermal leptogenesis can be relaxed accordingly.

Spontaneous breaking as the origin of the hot early universe

“…It is remarkable that the initial conditions of this radiation dominated phase are not free parameters but are determined by the parameters of a Lagrangian, which in principle can be measured by particle physics experiments and astrophysical observations. Our work is closely related to previous studies of thermal leptogenesis [11,12] and nonthermal leptogenesis via inflaton decay [13][14][15][16], where the inflaton lifetime determines the reheating temperature. In supersymmetric models with global B−L symmetry the scalar superpartner N 1 of the lightest heavy Majorana neutrino N 1 can play the role of the inflaton in chaotic [17,18] or hybrid [19,20] inflation models.…”

“…Eq. (16), which corresponds to a scale factor of a S 7.2 × 10 5 . Roughly up to this time the main part of the total energy is stored in these particles.…”

Dark-matter candidates

“…Moreover, for (nearly) mass-degenerate heavy righthanded Majorana neutrinos, resonant leptogenesis can explain the matter-antimatter asymmetry at smaller values of T R [248][249][250][251]. Another example for a framework in which the limit T R > 10 9 GeV is relaxed is non-thermal leptogenesis; see, e.g., [252] and references therein.…”

Gravitino Dark Matter

“…The type and masses of NLSP's consistent with leptogenesis and gravitino dark matter are strongly restricted by constraints from BBN (cf. ., the reheating temperature required for leptogenesis is smaller by about one order of magnitude [21,22]. If the reheating process, which leads to the temperature T R , is taken into account the constraints are sometimes relaxed.…”