Disentangling left and right-handed neutrino effects in B→K(∗)νν

The first observation of B(B+-> K+nu nu)bythe Belle II experiment lies almost 3 sigma 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 measureddecay rate and other observables, such asB(B -> K & lowast;nu nu)andFL(B -> K & lowast;nu nu), showing that they could disentangle among scenarios involving left-handed neutrinos and those with the right-handed ones. Furthermore, we find that thehigh -p Ttails of D rell-Yan processes studied at LHC pro-vide important constraints that help us exclude some of the scenarios consistent with the Belle II result.