Vector Leptoquark Mediated Leptonic Decay of the Charged $B$-Meson

TL;DR

This paper investigates the impact of a vector leptoquark model on the purely leptonic decay of the charged B-meson, including one-loop QCD corrections, and constrains the model using lattice data to predict potential lepton flavor universality violation effects.

Contribution

It provides the first detailed calculation of B-meson decay within the U1 vector leptoquark model, incorporating one-loop QCD corrections and lattice data constraints.

Findings

Predicted branching fractions with and without LFUV effects.

Constraints on leptoquark parameters from lattice-improved bounds.

Identification of potential signals of lepton flavor universality violation.

Abstract

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.