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Electroweak Baryogenesis
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Title: Electroweak Baryogenesis And The Fermi Gamma-Ray Line
Authors: Jonathan Kozaczuk, Stefano Profumo, Carroll L. Wainwright

Many particle physics models attempt to explain the 130 GeV gamma-ray feature that the Fermi-LAT observes in the Galactic Center. Neutralino dark matter in non-minimal supersymmetric models, such as the NMSSM, is an especially well-motivated theoretical setup which can explain the line. We explore the possibility that regions of the NMSSM consistent with the 130 GeV line can also produce the observed baryon asymmetry of the universe via electroweak baryogenesis. We find that such regions can in fact accommodate a strongly first-order electroweak phase transition (due to the singlet contribution to the effective potential), while also avoiding a light stop and producing a Standard Model-like Higgs in the observed mass range. Simultaneously, CP-violation from a complex phase in the wino-higgsino sector can account for the observed baryon asymmetry through resonant sources at the electroweak phase transition, while satisfying current constraints from dark matter, collider, and electric dipole moment (EDM) experiments. This result is possible by virtue of a relatively light pseudoscalar Higgs sector with a small degree of mixing, which yields efficient s-channel resonant neutralino annihilation consistent with indirect detection constraints, and of the moderate values of required to obtain a bino-like LSP consistent with the line. The wino mass is essentially a free parameter which one can tune to satisfy electroweak baryogenesis. Thus, the NMSSM framework can potentially explain the origins of both baryonic and dark matter components in the Universe. The tightness of the constraints we impose on this scenario makes it extraordinarily predictive, and conclusively testable in the near future by modest improvements in EDM and dark matter search experiments.

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RE: Baryogenesis
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Title: Baryon asymmetry and dark matter from soft leptogenesis
Authors: Heidi Kuismanen, Iiro Vilja

The framework for soft leptogenesis minimally extended with a DM sector is studied. A heavy singlet neutrino superfield acts as the source for (s)lepton asymmetry and by coupling to the singlet DM superfield it produces a DM particle density through decays. The nature of DM generated is twofold depending on whether the Yukawa and DM couplings are either small or large. With sufficiently small Yukawa and DM couplings DM annihilations into MSSM particles are slow and as a consequence all DM particles form the DM component. The solutions to Boltzmann equations are given and the dependence between the DM masses and coupling are presented in this weak coupling regime. Also, the behaviour of the efficiency of producing asymmetric DM is determined with weak couplings. We note that a different outcome arises if the couplings are larger because then the ADM component is dominant due to the effectiveness of DM decays into the MSSM sector.

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Title: Baryogenesis from Mixing of Lepton Doublets
Authors: Bjorn Garbrecht

It is shown that the mixing of lepton doublets of the Standard Model can yield sizeable contributions to the lepton asymmetry, that is generated through the decays of right-handed neutrinos at finite temperature in the early Universe. When calculating the flavour-mixing correlations, we account for the effects of Yukawa as well as of gauge interactions. We compare the freeze-out asymmetry from lepton-doublet mixing to the standard contributions from the mixing and direct decays of right-handed neutrinos. The asymmetry from lepton mixing is considerably large when the mass ratio between the right-handed neutrinos is of order of a few, while it becomes Maxwell-suppressed for larger hierarchies. For an intermediate range between the case of degenerate right-handed neutrinos (resonant Leptogenesis) and the hierarchical case, lepton mixing can yield the main contribution to the lepton asymmetry.

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Title: Matter and Antimatter in the Universe
Authors: Laurent Canetti, Marco Drewes, Mikhail Shaposhnikov

We review observational evidence for a matter-antimatter asymmetry in the early universe, which leads to the remnant matter density we observe today. We also discuss observational bounds on the presence of antimatter in the present day universe, including the possibility of a large lepton asymmetry in the cosmic neutrino background. We briefly review the theoretical framework within which baryogenesis, the dynamical generation of a matter-antimatter asymmetry, can occur. As an example, we discuss a testable minimal model that simultaneously explains the baryon asymmetry of the universe, neutrino oscillations and dark matter.

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Title: Neutrino Mass Hierarchy and neutron-anti-neutron Oscillation from Baryogenesis
Authors: K. S. Babu, P. S. Bhupal Dev, R. N. Mohapatra
(Version v3)

It has been recently proposed that the matter-antimatter asymmetry of the universe may have its origin in "post-sphaleron baryogenesis" (PSB). It is a TeV scale mechanism that is testable at the LHC and other low energy experiments. In this paper we present a theory of PSB within a quark-lepton unified scheme based on the gauge group SU(2)_L x SU(2)_R x SU(4)_c that allows a direct connection between the baryon asymmetry and neutrino mass matrix. The flavour changing neutral current constraints on the model allow successful baryogenesis only for an inverted mass hierarchy for neutrinos, which can be tested in the proposed long base line neutrino experiments. The model also predicts observable neutron--antineutron oscillation accessible to the next generation of experiments as well as TeV scale coloured scalars within reach of LHC.

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