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

Understand

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.