Enhanced $B_q\to \ell {\ell }^{\prime }$ and $B\to (K,\pi )\ell {\ell }^{\prime }$ in light of $(g-2{)}_{\mu }$

Abstract

We study lepton flavor violating (LFV) $B$ decays in a general two Higgs doublet model with sub-TeV exotic scalars. Two different parameter spaces are explored: one dominated by extra top Yukawa coupling ${\rho }_{tt}$, the other by LFV couplings relevant for the muon $g-2$ anomaly. In the first case, flavor constraints such as $\ell \to {\ell }^{\prime }\gamma$, $h\to \ell {\ell }^{\prime }$ imply LFV $B$ decays are far below experimental sensitivities. The second case needs to be close to the alignment limit, but $B_q\to \tau \mu$ and $B\to (K,\pi )\tau \mu$ rates can lie within the sensitivities of Belle II and LHCb Upgrade II. Neutral $B$ meson mixings and $B,K,\pi \to \ell \nu$ decays provide important flavor constraints on parameter space. $B$ decays involving $e$-$\tau$ violation are constrained by $\mu \to e$ processes.

Comments: 11 pages, 6 captioned figures, added a discussion of collider signatures in section IV and included a new appendix; matches published version