Disentangling left and right-handed neutrino effects in B K^ (*)

The first observation of B (B^+ K^+) by the Belle II experiment lies almost 3 away from the Standard Model expectation. In this letter we study this result in the SMEFT, extended by a light right-handed neutrino. We explore the correlations between the measured decay rate and other observables, such as B (B K^*) and FL (B K^*), showing that they could disentangle among scenarios involving left-handed neutrinos and those with the right-handed ones. Furthermore, we find that the high-pT tails of Drell-Yan processes studied at LHC provide important constraints that help us exclude some of the scenarios consistent with the Belle II result.