11 research outputs found
Wash-Out in N_2-dominated leptogenesis
We study the wash-out of a cosmological baryon asymmetry produced via
leptogenesis by subsequent interactions. Therefore we focus on a scenario in
which a lepton asymmetry is established in the out-of-equilibrium decays of the
next-to-lightest right-handed neutrino. We apply the full classical Boltzmann
equations without the assumption of kinetic equilibrium and including all
quantum statistical factors to calculate the wash-out of the lepton asymmetry
by interactions of the lightest right-handed state. We include scattering
processes with top quarks in our analysis. This is of particular interest since
the wash-out is enhanced by scatterings and the use of mode equations with
quantum statistical distribution functions. In this way we provide a
restriction on the parameter space for this scenarios.Comment: 26 pages, 4 figures, profound revision, exposition is now in flavor
notation, one plot and discussion added, numerical error corrected, three
plots changed, text polished, main results remain unchanged, reference
added,matches published versio
Leptogenesis from Soft Supersymmetry Breaking (Soft Leptogenesis)
Soft leptogenesis is a scenario in which the cosmic baryon asymmetry is
produced from a lepton asymmetry generated in the decays of heavy sneutrinos
(the partners of the singlet neutrinos of the seesaw) and where the relevant
sources of CP violation are the complex phases of soft supersymmetry-breaking
terms. We explain the motivations for soft leptogenesis, and review its basic
ingredients: the different CP-violating contributions, the crucial role played
by thermal corrections, and the enhancement of the efficiency from lepton
flavour effects. We also discuss the high temperature regime GeV in
which the cosmic baryon asymmetry originates from an initial asymmetry of an
anomalous -charge, and soft leptogenesis reembodies in -genesis.Comment: References updated. Some minor corrections to match the published
versio
Examining leptogenesis with lepton flavor violation and the dark matter abundance
Within a supersymmetric (SUSY) type-I seesaw framework with flavor-blind
universal boundary conditions, we study the consequences of requiring that the
observed baryon asymmetry of the Universe be explained by either thermal or
non-thermal leptogenesis. In the former case, we find that the parameter space
is very constrained. In the bulk and stop-coannihilation regions of mSUGRA
parameter space (that are consistent with the measured dark matter abundance),
lepton flavor-violating (LFV) processes are accessible at MEG and future
experiments. However, the very high reheat temperature of the Universe needed
after inflation (of about 10^{12} GeV) leads to a severe gravitino problem,
which disfavors either thermal leptogenesis or neutralino dark matter.
Non-thermal leptogenesis in the preheating phase from SUSY flat directions
relaxes the gravitino problem by lowering the required reheat temperature. The
baryon asymmetry can then be explained while preserving neutralino dark matter,
and for the bulk or stop-coannihilation regions LFV processes should be
observed in current or future experiments.Comment: 20 pages, 5 figures, 1 tabl
Towards leptogenesis at NLO: the right-handed neutrino interaction rate
We compute quantum and thermal corrections to the right-handed neutrino
interaction rate in the early universe at next-to-leading order in all the
relevant SM couplings (gauge, top Yukawa and higgs couplings). Previous
computations considered 2 -> 2 scatterings, finding infra-red divergences. The
KLN theorem demands that infra-red divergences cancel in the full result: after
adding 1 -> 3 and one-loop virtual corrections that enter at the same order we
find a simple result.Comment: 20 pages, 9 figures, error fixed in an equation right after Eqs.
(18); v4: experimental value of the Higgs mass consistently include
Higgs, Moduli Problem, Baryogenesis and Large Volume Compactifications
We consider the cosmological moduli problem in the context of high-scale
supersymmetry breaking suggested by the recent discovery of the standard-model
like Higgs boson. In order to solve the notorious moduli-induced gravitino
problem, we focus on the LARGE volume scenario, in which the modulus decay into
gravitinos can be kinematically forbidden. We then consider the Affleck-Dine
mechanism with or without an enhanced coupling with the inflaton, taking
account of possible Q-ball formation. We show that the baryon asymmetry of the
present Universe can be generated by the Affleck-Dine mechanism in LARGE volume
scenario, solving the moduli and gravitino problems. We also find that the
overall volume modulus decays into a pair of the axionic superpartners, which
contribute to the extra relativistic degrees of freedom.Comment: 46 pages; v2: Comments and references added; v3: dilution factor in
the published version corrected, conclusion unchange