Minimal Lepton Flavor Violation Implications of the $b\to s$ Anomalies

Abstract

The latest measurements of rare $b\to s$ decays in the LHCb experiment have led to results in tension with the predictions of the standard model (SM), including a tentative indication of the violation of lepton flavor universality. Assuming that this situation will persist because of new physics, we explore some of the potential consequences in the context of the SM extended with the seesaw mechanism involving right-handed neutrinos plus effective dimension-six lepton-quark operators under the framework of minimal flavor violation. We focus on a couple of such operators which can accommodate the LHCb anomalies and conform to the minimal flavor violation hypothesis in both their lepton and quark parts. We examine specifically the lepton-flavor-violating decays $B\to K^{(*)}\ell\ell'$, $B_s\to\phi\ell\ell'$, $B\to(\pi,\rho)\ell\ell'$, and $B_{d,s}\to\ell\ell'$, as well as $K_L\to e\mu$ and $K\to\pi e\mu$, induced by such operators. The estimated branching fractions of some of these decay modes with $\mu\tau$ in the final states are allowed by the pertinent experimental constraints to reach a few times $10^{-7}$ if other operators do not yield competitive effects. We also look at the implications for $B\to K^{(*)}\nu\nu$ and $K\to\pi\nu\nu$, finding that their rates can be a few times larger than their SM values. These results are testable in future experiments.