Global Bayesian Analysis of new physics in $b \to s \mu\mu$ transitions after Moriond-2019

TL;DR

This paper conducts a comprehensive Bayesian analysis of new physics effects in $b o s \mu\mu$ transitions, incorporating recent experimental data to evaluate and compare various beyond Standard Model scenarios.

Contribution

It introduces a global Bayesian framework for analyzing $b o s \\mu\\mu$ anomalies, including new measurements and model comparisons with predictions for BSM couplings and masses.

Findings

Support for lepton flavor universality violation from recent data

Bayesian credibility regions for various NP scenarios

Model comparison via Bayes factors indicating favored BSM models

Abstract

The recent measurement of $R_K$ at LHCb continues to support the hint of violation of lepton flavor universality. We perform a global fit for new physics in semileptonic $b\to s$ transitions using all the relevant data with a Bayesian analysis technique. We include new measurements of $R_K$ at LHCb and new determinations of $R_{K^*}$ and $R_{K^{*+}}$ at Belle. We perform the scan for various NP scenarios and infer the 68\% and 95.4\% credibility regions of the marginalized posterior probability density for all scenarios. We also compare the models in pairs by calculating the Bayes factor given a common data set. A few well-known BSM models are analyzed that can provide a high energy framework for the EFT analysis. These include the exchange of a heavy $Z^{'}$ 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.