Vector leptoquark resolution of $R_K$ and $R_{D^{(*)}}$ puzzles

Abstract

We propose that three recent anomalies in $B$ meson decays, $R_{D^{(*)}}$, $R_K$, and $P_5'$, might be explained by a single vector leptoquark weak triplet state. The constraints on the parameter space are obtained by considering $t \to b \tau^+ \nu$ data, lepton flavor universality tests in the kaon sector, bounds on $B \to K^{(*)} \bar \nu \nu$, bound on the lepton flavor violating decay $B \to K \mu \tau$, and measurements of $b \to c \mu^- \bar\nu$ decays. The presence of such vector leptoquark could be exposed in precise measurements of $t \to b \tau \nu$ and $B \to K^{(*)} \bar \nu \nu$ decays. The model also predicts approximate equality of lepton flavor universality ratios $R_{K^*}$, $R_{K}$, and suppressed branching fraction of $B_s \to \mu^+ \mu^-$.