Understanding the B->K*mu+mu- Anomaly

TL;DR

This paper analyzes anomalies in B->K*mu+mu- decays, suggesting they may be due to new physics affecting Wilson coefficients, with a significant deviation from the Standard Model predictions.

Contribution

It provides a comprehensive global analysis of recent LHCb data, identifying potential new physics contributions to Wilson coefficients C7 and C9 as explanations for observed anomalies.

Findings

4.5 sigma deviation from SM with primary observables

Reduced significance to 3.9 sigma when including low-recoil data

No systematic errors found that alter conclusions

Abstract

We present a global analysis of the B->K*(->K pi)mu+mu- decay using the recent LHCb measurements of the primary observables P_{1,2} and P'_{4,5,6,8}. Some of them exhibit large deviations with respect to the SM predictions. We explain the observed pattern of deviations through a large New Physics contribution to the Wilson coefficient of the semileptonic operator O9. This contribution has an opposite sign to the SM one, i.e., reduces the size of this coefficient significantly. A good description of data is achieved by allowing for New Physics contributions to the Wilson coefficients C7 and C9 only. We find a 4.5 sigma deviation with respect to the SM prediction, combining the large-recoil B->K*(->K pi)mu+mu- observables with other radiative processes. Once low-recoil observables are included the significance gets reduced to 3.9 sigma. We have tested different sources of systematics, none of them modifying our conclusions significantly. Finally, we propose additional ways of measuring the primary observables through new foldings.