1202.2348 (Devin G. E. Walker)

Dark Baryogenesis    [PDF]

Devin G. E. Walker

We first suggested a scenario in which a generic, dark chiral gauge group
undergoes a first order phase transition in order to generate the observed
baryon asymmetry in the universe, provide a viable dark matter candidate and
explain the observed baryon-to-dark matter ratio of relic abundances
[arXiv:1003.0899]. We now provide a model in which a copy of the electroweak
gauge group is added to the Standard Model. We spontaneously break this new
gauge group to the diagonal Z_2 center which is used to stabilize a dark matter
candidate. In addition to the dark matter candidate, anomaly free messenger
fermions are included which transform non-trivially under all the gauge groups.
In analogy to electroweak baryogenesis, the model generates an excess of
messenger "baryons". These "baryons" subsequently decay to the Standard Model
and dark matter to generate an excess of Standard Model baryons. The
baryon-to-dark matter number density ratio is ultimately due to the requirement
of gauge anomaly freedom. Dark sphalerons generate operators which violate B -
L but preserves B + L. Thus, the asymmetry is not washed out by the Standard
Model. The model radiatively generates a dark matter mass of order of the
electroweak vacuum expectation value suppressed by a loop factor therefore
setting the dark matter-to-baryon relic abundance. We outline some distinctive
experimental signatures and ensure these models are consistent with existing
constraints. As first discussed in [arXiv:0907.3146], these dark matter
scenarios feature long-lived particles which can be observed at colliders. We
finally show how approximate global symmetries in the higgs sector stabilize
both the dark and electroweak scales thereby mitigating the hierarchy problem.
Light dark higgses are needed to ensure the correct relic abundance. Thus, by
construction the SM and dark higgses generate masses at two- and three-loops,
respectively.

View original: http://arxiv.org/abs/1202.2348