Abstract
We consider a model in which baryogenesis occurs at low scale, at a temperature below the electroweak phase transition. This model involves new diquark-type scalars which carry baryon number. Baryon number violation is introduced in the scalar potential, permitting $\Delta B=2$ violating process involving Standard Model quarks while avoiding stringent proton decay constraints. Depending on their quantum number assignment, the diquark-type scalars can couple to either right or left handed quarks, or to both. We show that this model can provide a viable explanation of the baryon asymmetry of the universe provided that the coupling to left handed quarks are present. However, the coexistence of couplings to left and right handed quarks introduces important phenomenological constraints on the model, such as radiative contributions to quark masses and the generation of electric dipole moments for nuclei, which probe the CP even and CP odd products of the relevant couplings constants, respectively. We demonstrate that the strongest such constraints arise from electric dipole moment measurements of the neutron and $^{199}$Hg. These constraints are sufficiently strong that, in the absence of an intricate flavor structure, baryogenesis must be dominated by the couplings of the new scalars to left handed quarks.
Highlights
A major outstanding question in fundamental physics is the origin of the cosmological matter-antimatter asymmetry
A well studied mechanism is that of electroweak baryogenesis (EWBG) [1,2,3,4] where an asymmetry is generated via CP violating interactions during a first order electroweak phase transition with the requisite B violation provided by electroweak sphalerons
Calculating the one loop generated up quark mass at the quark mass scale after running down from the new physics (NP) scale and requiring it be smaller than the tree level quark mass gives the constraint: δmuj jGÃijG0ijj log ðmuj Þ2 M2Δud
Summary
A major outstanding question in fundamental physics is the origin of the cosmological matter-antimatter asymmetry. New sources of CPV must be introduced as the SM Jarlskog factor is suppressed by small CKM matrix elements and small quark masses These challenges notwithstanding, electroweak baryogenesis has the appealing feature of being a weakscale mechanism and eminently testable. In this paper we consider an out-of-equilibrium decay process which occurs at an experimentally accessible energy scale In this sense, the mechanism shares the endearing features of both leptogenesis and EWBG. We shall calculate EDMs together with naturalness constraints on radiative quark mass contributions, which place bounds on CP odd and CP even products, respectively, of the new coupling parameters in our model. These constraints will dictate which of the new couplings can play a role in baryogenesis.
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