Disentangling left and right-handed neutrino effects in $B\to K^{(\ast )}\nu \nu$

Abstract

The first observation of $\mathcal{B}\left(B^{+}\to K^{+}\nu \nu \right)$ by the 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 measured decay rate and other observables, such as $\mathcal{B}\left(B\to K^{\ast }\nu \nu \right)$ and $F_L\left(B\to K^{\ast }\nu \nu \right)$, showing that they could disentangle among scenarios involving left-handed neutrinos and those with the right-handed ones. Furthermore, we find that the high-$p_T$ 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.

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