Explaining the Flavor Anomalies with a Vector Leptoquark (Moriond 2019 update)

Several experiments revealed intriguing hints for lepton flavor universality (LFU) violating new physics (NP) in semi-leptonic $B$ meson decays, mainly in $b \to c \tau \nu$ and $b \to s \ell^+ \ell^-$ transitions at the $3-5\,\sigma$ level. Leptoquarks (LQ) are prime candidates to address these anomalies as they contribute to semi-leptonic decays already at tree level while effects in other flavor observables, agreeing with the standard model (SM), are loop suppressed. In these proceedings we review the vector leptoquark $SU(2)_L$ singlet, contained in the famous Pati-Salam model, which is able to address both $b \to c\tau \nu$ and $b \to s \mu^+ \mu^-$ data simultaneously. Due to the large couplings to tau leptons needed to account for the $b \to c \tau \nu$ data, sizable loop effects arise which we include in our phenomenological analysis. Updating our previous result with the recent measurements of LHCb and BELLE we find an even better fit to data than before.