Speaker
Description
Semileptonic flavor changing neutral current transitions of $B$-mesons with a pair of neutrinos in the final state are very accurately determined in the standard model (SM) and, thus, provide a sensitive probe for physics beyond the SM. Until recently, the poor tagging efficiency for the $B\to K^{(*)}\nu\bar{\nu}$ modes made them less advantageous as a probe of new physics (NP) compared to the charged lepton counterparts. The most recent Belle II result on $B^+\to K^+\nu\bar{\nu}$ indicates a possible enhancement in the branching fraction of $B^+\to K^+\nu\bar{\nu}$. Therefore we explore the possibilities of an enhancement in a set of observables for $B\to K^{(*)}\nu\bar{\nu}$. We considered the weak effective theory extended by vector effective operators both with light left- and right-handed neutrinos. The latter can appear in various SM extensions, e.g., in models with additional $Z'$ boson.
