Explaining the $R_{K}$ and $R_{D^{(*)}}$ anomalies with vector leptoquarks

TL;DR

This paper explores how vector leptoquarks can simultaneously explain anomalies in $R_K$ and $R_{D^{(*)}}$ observed in B meson decays, by constraining their parameters with experimental data and analyzing various decay observables.

Contribution

It demonstrates that vector leptoquarks can account for multiple B decay anomalies simultaneously, providing a unified explanation within this new physics framework.

Findings

Vector leptoquarks can explain $R_{D^{(*)}}$ and $R_K$ anomalies.

Leptoquark parameter space is constrained by B decay measurements.

Predictions for polarization and asymmetries in B decays are consistent with anomalies.

Abstract

Recently the $B$ factories BaBar and Belle as well as the LHCb experiment have reported several anomalies in the semileptonic $B$ meson decays such as $R_{K}$ and $R_{D^{(*)}}$ etc. We investigate these deviations by considering the vector leptoquarks relevant for both $b \to s l^+ l^-$ and $b \to c l \bar \nu_l$ transitions. The leptoquark parameter space is constrained by using the experimentally measured branching ratios of $B_s \to l^+ l^-$, $\bar B \to X_s l^+ l^- (\nu \bar \nu)$ and $B_u^+ \to l^+ \nu_l$ processes. Using the constrained leptoquark couplings, we compute the branching ratios, forward-backward asymmetries, $\tau$ and $D^*$ polarization parameters in the $\bar B \to D^{(*)} l \bar \nu_l$ processes. We find that the vector leptoquarks can explain both $R_{D^{(*)}}$ and $R_K$ anomalies simultaneously. Furthermore, we study the rare leptonic $B_{u, c}^* \to l \bar\nu$ decay processes in this model.