Vector Leptoquark Mediated Leptonic Decay of the Charged $B$-Meson
We study the purely leptonic decay of the charged $B$-meson within the $U_1$ Vector Leptoquark model at both leading-order and with one-loop QCD corrections. The structure of this amplitude is characterised by direct quark-lepton couplings which allow for lepton flavour universality violation (LFUV) and additional loop-level topologies. The leptoquark channel contributions to the $B$-meson decay constant are computed and accommodated in its lattice-improved uncertainty bounds by constraining the parameter space of this model in two distinct new-physics scenarios. Under these constraints, we provide predictions for both the LFUV and non-LFUV contributions to the branching fractions of this decay.
hep-ph↗