Hard-thermal-loop corrections in leptogenesis I:CP-asymmetries

Abstract

We investigate hard-thermal-loop (HTL) corrections to the CP -asymmetries in neutrino and, at high temperature, Higgs boson decays in leptogenesis. We pay special attention to the two leptonic quasiparticles that arise at non-zero temperature and find that there are four contributions to the CP -asymmetries, which correspond to the four combinations of the two leptonic quasiparticles in the loop and in the final states. In two additional cases, we approximate the full HTL-lepton propagator with a zero-temperature propagator that employs the thermal lepton mass m ℓ (T ), or the asymptotic thermal lepton mass √ 2 m ℓ (T ). We find that the CPasymmetries in the one-mode approaches differ by up to one order of magnitude from the full two-mode treatment in the interesting temperature regime T ∼ M 1 . The asymmetry in Higgs boson decays turns out to be two orders of magnitude larger than the asymmetry in neutrino decays in the zero-temperature treatment. The effect of HTL corrections on the final lepton asymmetry are investigated in paper II of this series.

Three-loop HTLpt thermodynamics at finite temperature and chemical potential

“…Quantities such as the dilepton production rate [96,97], photon production rate [98], single quark and quark anti-quark potentials [99][100][101][102][103][104][105][106][107], fermion damping rate [108][109][110], photon damping rate [111], gluon damping rate [112,113], jet energy loss [114][115][116][117][118][119][120][121][122][123][124][125], plasma instabilities [126][127][128][129][130][131][132], thermal axion production [133], and lepton asymmetry during leptogenesis [134,135] have also been calculated using HTLpt. We note, however, that most of the papers above have only worked at what we would call leading order in HTLpt.…”

NonthermalCPviolation in soft leptogenesis

“…The above also implies that in Eq. (A7) we have ignored the fact that due to the interactions with the thermal bath the two poles of the fermion propagator have different dispersion relations which can lead to an order of magnitude correction to leptogenesis in the weak washout regime and an order of 1 correction in the strong washout regime [45][46][47].…”

CP asymmetry in heavy Majorana neutrino decays at finite temperature: the hierarchical case

“…Several investigations of the lepton-number asymmetry have been carried out either within the Boltzmann rate equations and their quantum version known as Kadanoff-Baym equations [22][23][24][25]. Thermal effects are typically accounted for by including thermal masses and thermal distributions for the Higgs bosons and leptons appearing as decay products of heavy Majorana neutrinos.…”

“…The present study complements an analogous recent study [19] for the case of two heavy Majorana neutrinos with nearly degenerate masses relevant for resonant leptogenesis. Thermal corrections at zeroth order in SM couplings of the type given in [22][23][24] are exponentially suppressed in the non-relativistic regime and, therefore, not accounted for by an expansion in T /M 1 . Nevertheless, as discussed in appendix C of [19], one could easily retain the leading exponentially suppressed terms by a suitable modification of the calculation.…”