Implications for New Physics in $b\to s\mu \mu$ transitions after recent measurements by Belle and LHCb

Abstract

We present a Bayesian analysis of the implications for new physics in semileptonic $b\to s$ transitions after including new measurements of $R_K$ at LHCb and new determinations of $R_{K^{\ast }}$ and $R_{K^{\ast +}}$ at Belle. We perform global fits with 1, 2, 4, and 8 input Wilson coefficients, plus one CKM nuisance parameter to take into account uncertainties that are not factorizable. We infer the 68% and 95.4% credibility regions of the marginalized posterior probability density for all scenarios and perform comparisons of models in pairs by calculating the Bayes factor given a common data set. We then proceed to analyzing a few well known BSM models that can provide a high energy framework for the EFT analysis. These include the exchange of a heavy $Z^{{}^{\prime }}$ boson in models with heavy vector-like fermions and a scalar field, and a model with scalar leptoquarks. We provide predictions for the BSM couplings and expected mass values.

Comments: 22 pages, 6 figures, 23 tables. v3: Minor modifications to the text, references added. Published version