Leptoquarks in Flavour Physics

Dario Müller

doi:10.1051/epjconf/201817901015

Abstract

While the LHC has not directly observed any new particle so far, experimental results from LHCb, BELLE and BABAR point towards the violation of lepton flavour universality in b ⟶ sℓ+ and b ⟶ c-ℓν. In this context, also the discrepancy in the anomalous magnetic moment of the muon can be interpreted as a sign of lepton flavour universality violation. Here we discuss how these hints for new physics can also be explained by introducing leptoquarks as an extension of the Standard Model. Indeed, leptoquarks are good candidates to explain the anomaly in the anomalous magnetic moment of the muon because of an mg/mμ enhanced contribution giving correlated effects in Z boson decays which is particularly interesting in the light of future precision experiments.

Highlights

The LHC has not directly observed any particles beyond the ones in the Standard Model of particle physics (SM)
The discrepancy in the anomalous magnetic moment of the muon can be interpreted as a sign of lepton flavour universality violation
We discuss how these hints for new physics can be explained by introducing leptoquarks as an extension of the Standard Model

Summary

Introduction

The LHC has not directly observed any particles beyond the ones in the Standard Model of particle physics (SM). If we allow for couplings of the top quark to taus or electrons, lepton flavour violating processes as τ → μγ or Z → μe will be possible. Lint = κ3f iQ f γμ τ · V3μ Li. If we only allow for couplings to muons, these LQ will give tree-level effects in b → sμ+μ− but contribute at looplevel in other flavour observables. If we only allow for couplings to muons, these LQ will give tree-level effects in b → sμ+μ− but contribute at looplevel in other flavour observables This is why LQ can explain the anomalies in b → sμ+μ− transitions but are not in conflict with other observables. We get additional effects in b → se+e− as well as in the lepton flavour violating processes μ → eγ and b → sμe.

Simultaneous Explanation

Conclusion