Phenomenology of decays in a scalar leptoquark model * * Supported by the National Natural Science Foundation of China (11775092, 11521064, 11435003, 11805077). XY is also supported in part by the startup research funding from CCNU

Abstract

During the past few years, signs of lepton flavor universality (LFU) violation have been observed in and transitions. Recently, the and polarization fractions and in decay were likewise measured by the Belle collaboration. Motivated by these intriguing results, we revisit the and anomalies in a scalar leptoquark (LQ) model, where two scalar LQs, one of which is a singlet and the other a triplet, are introduced simultaneously. We consider five mediated decays, , , , and , and focus on the LQ effects on the distributions of the branching fractions, LFU ratios, and various angular observables in these decays. Under the combined constraints of the available data on , , , and , we perform scans for the LQ couplings and make predictions for a number of observables. Numerically it is found that both the differential branching fractions and LFU ratios are largely enhanced by the LQ effects, with the latter expected to provide testable signatures at the SuperKEKB and High-Luminosity LHC experiments.