Signal of right-handed currents using $B\to K^*\ell^+\ell^-$ observables at the kinematic endpoint

TL;DR

This paper analyzes $B\to K^*\ell^+\ell^-$ decay observables at the kinematic endpoint to find evidence of right-handed currents, providing a hadronic correction-free method that complements low $q^2$ studies.

Contribution

It introduces a novel approach using heavy quark symmetries at the maximum $q^2$ endpoint to detect right-handed currents without hadronic uncertainties.

Findings

Evidence for right-handed currents in LHCb data

Method free from hadronic correction uncertainties

Complementary to low $q^2$ new physics probes

Abstract

The decay mode $B\to K^*\ell^+\ell^-$ is one of the most promising modes to probe physics beyond the standard model (SM), since the angular distribution of the decay products enable measurement of several constraining observables. LHCb has recently measured these observables using $3fb^{-1}$ of data as a binned function of $q^2$, the dilepton invariant mass squared. We find that LHCb data implies evidence for right-handed currents, which are absent in the SM. These conclusions are derived in the maximum $q^2$ limit and are free from hadronic corrections. Our approach differs from other approaches that probe new physics at low $q^2$ as it does not require estimates of hadronic parameters but relies instead on heavy quark symmetries that are reliable at the maximum $q^2$ kinematic endpoint.