AnomalousB-meson mixing and baryogenesis

Abstract

There exist experimental hints from the B sector for CP violation beyond the Standard Model (SM) CKM paradigm. An anomalous dimuon asymmetry was reported by the D0 collaboration, while tension exists between $B \to \tau \nu$ and $S_{\psi K}$. These measurements, disfavoring the SM at the ~3$\sigma$ level, can be explained by new physics in both $B_d$-$\bar{B}_d$ and $B_s$- $\bar{B}_s$ mixing, arising from (1) new bosonic degrees of freedom at or near the electroweak scale, and (2) new, large CP-violating phases. These two new physics ingredients are precisely what is required for electroweak baryogenesis to work in an extension of the SM. We show that a simple two Higgs doublet model with top-charm flavor violation can explain the B anomalies and the baryon asymmetry of the Universe. Moreover, the presence of a large relative phase in the top-charm Yukawa coupling, favored by $B_{d,s}$-$\bar{B}_{d,s}$ mixing, weakens constraints from $\epsilon_K$ and $b \to s \gamma$, allowing for a light charged Higgs mass of O(100 GeV).