New Physics in the Flavour Sector

TL;DR

This paper reviews recent experimental anomalies in the flavour sector involving muons and taus, discusses their potential correlations, and explores models that could explain these deviations from the Standard Model.

Contribution

It provides a comprehensive overview of current flavour anomalies and evaluates models that could simultaneously address multiple deviations.

Findings

Multiple experiments observe deviations from the SM in flavour transitions.

Hints of lepton flavour universality violation are present in B decays.

Potential models can explain several anomalies simultaneously.

Abstract

Several experiments observed deviations from the Standard Model (SM) in the flavour sector: LHCb found a $4-5\,\sigma$ discrepancy compared to the SM in $b\to s\mu^+\mu^-$ transitions (recently supported by an Belle analysis) and CMS reported a non-zero measurement of $h\to\mu\tau$ with a significance of $2.4\,\sigma$. Furthermore, BELLE, BABAR and LHCb founds hints for the violation of flavour universality in $B\to D^{(*)}\tau\nu$. In addition, there is the long-standing discrepancy in the anomalous magnetic moment of the muon. Interestingly, all these anomalies are related to muons and taus, while the corresponding electron channels seem to be SM like. This suggests that these deviations from the SM might be correlated and we briefly review some selected models providing simultaneous explanations.