Vector leptoquarks beyond tree level. III. Vectorlike fermions and flavor-changing transitions

Abstract

Extending previous work on this subject, we evaluate the impact of vectorlike fermions at next-to-leading order accuracy in models with a massive vector leptoquark embedded in the SU(4)×SU(3)′×SU(2)L×U(1)X gauge group. Vectorlike fermions induce new sources of flavor symmetry breaking, resulting in tree-level flavor-changing couplings for the leptoquark not present in the minimal version of the model. These, in turn, lead to a series of nonvanishing flavor-changing neutral-current amplitudes at the loop level. We systematically analyze these effects in semileptonic, dipole and ΔF=2 operators. The impact of these corrections in b→sνν and b→cτν observables are discussed in detail. In particular, we show that, in the parameter region providing a good fit to the B-physics anomalies, the model predicts a 10% to 50% enhancement of B(B→K(*)νν).