3 research outputs found
Hard-Thermal-Loop Corrections in Leptogenesis I: CP-Asymmetries
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 sqrt{2}
m_l(T). We find that the CP-asymmetries 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 \sim 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.Comment: 38 pages, 14 figure
Decay of a Yukawa fermion at finite temperature and applications to leptogenesis
We calculate the decay rate of a Yukawa fermion in a thermal bath using
finite temperature cutting rules and effective Green's functions according to
the hard thermal loop resummation technique. We apply this result to the decay
of a heavy Majorana neutrino in leptogenesis. Compared to the usual approach
where thermal masses are inserted into the kinematics of final states, we find
that deviations arise through two different leptonic dispersion relations. The
decay rate differs from the usual approach by more than one order of magnitude
in the temperature range which is interesting for the weak washout regime. We
discuss how to arrive at consistent finite temperature treatments of
leptogenesis.Comment: 16 pages, 5 figure
Hard-Thermal-Loop Corrections in Leptogenesis II: Solving the Boltzmann Equations
We investigate hard-thermal-loop (HTL) corrections to the final lepton
asymmetry in leptogenesis. To this end we solve the Boltzmann equations with
HTL-corrected rates and CP asymmetries, which we calculated in paper I of this
series. We pay special attention to the influence of the two leptonic
quasiparticles that arise at non-zero temperature. We include only decays and
inverse decays and allow for the lepton modes to be either decoupled from each
other, or to be in chemical equilibrium by some strong interaction, simulating
the interaction with gauge bosons. In two additional cases, we approximate the
full HTL lepton propagators with zero-temperature propagators, where we replace
the zero-temperature mass by the thermal mass of the leptons or the
asymptotic mass . We compare the final lepton
asymmetries of the four thermal cases and the zero-temperature case for zero,
thermal and dominant initial neutrino abundance. The final lepton asymmetries
of the thermal cases differ considerably from the vacuum case and from each
other in the weak washout regime for zero initial neutrino abundance and in the
intermediate regime for dominant initial neutrino abundance. In the strong
washout regime, the final lepton asymmetry can be enhanced by a factor of two
in the case of strongly interacting lepton modes.Comment: 51 pages, 27 figure