Electroweak baryogenesis, CDM and anomaly-free supersymmetric U(1)′ models

We construct an anomaly-free supersymmetric U(1)' model with a secluded U(1)'-breaking sector (sMSSM), with E-6 embedding. Then we systematically study electroweak baryogenesis (EWBG) driven by spontaneous CP-violation (SCPV), using the sMSSM as an example. Unlike the Minimal Supersymmetric Standard Model (MSSM), CP violation in the Higgs sector can be both spontaneous and explicit in the sMSSM, even at tree level. These new CP sources do not introduce significant new contributions to electric dipole moments of the electron and neutron. Novel features are found in the EWBG driven by SCPV (significantly different from the ones in the MSSM). First, due to the space-dependence of the relevant CP phases, the CP-violating stop and chargino currents do not require a variation of tan beta in the bubble wall to have a non-trivial structure at the lowest order of Higgs insertion. Second, there exists a new type of CP-violating current at the leading order. Because of this, in addition to leptons and charginos, top quarks and top squarks can also play a significant role in the EWBG. Numerical results show that the baryon asymmetry is large enough to explain the cosmological observation today. We illustrate that EWBG and neutralino cold dark matter can be accommodated in the same framework, i.e., there exists parameter space where a strong enough first order EWPT, large CP phase variations across the bubble wall, a reasonable baryon asymmetry as well as an acceptable neutralino dark matter relic density can be achieved simultaneously.