$b\to s\gamma$, electron EDM and electroweak baryogenesis: a study in general 2HDM

Abstract

We study inclusive $b\to s\gamma$ decay in the context of electron EDM and baryogenesis. The general 2HDM (i.e. without $Z_2$) that possesses an extra set of Yukawa matrices can drive electroweak baryogensis via ${\lambda }_t\mathrm{Im}{\rho }_{tt}$, where ${\rho }_{tt}$ is the extra diagonal top Yukawa coupling, with the $e$EDM constraint evaded by an exquisite flavor cancellation mechanism. We touch upon the current status of direct search for exotic $H$, $A$ and $H^{+}$ scalars at the LHC, while for the plethora of flavor observables in $g$2HDM, we focus on $b\to s\gamma$, pointing out $chiral$ enhancement of a ${\rho }_{tt}{\rho }_{bb}$ effect in $g$2HDM, which can bring in a CPV phase. We first explore the inclusive $\mathcal{B}(b\to s\gamma )$ rate, then showcase the progress that Belle II can make in the future, illustrating a potential 3$\sigma$ effect for the inclusive $B^{+}\to X_s^{+}\gamma$ vs $B^0\to X_s^0\gamma$ CPV rate difference, $\Delta A_{\mathrm{CP}}$. Especially if $e$EDM emerges swiftly, perhaps one should pursue further upgrade beyond Belle II.

Comments: 6 pages, 7 figures, EPS-HEP2023