$B$ meson anomalies and large $B^{+}\to K^{+}\nu\bar{\nu}$ in non-universal $U(1)^\prime$ models

TL;DR

This paper analyzes recent anomalies in B meson decays, showing that non-universal U(1)' models without flavor violation cannot fully explain the data, but introducing lepton flavor violation can reconcile the models with observations.

Contribution

It demonstrates the limitations of flavor-conserving non-universal U(1)' models and proposes a new approach involving lepton flavor violation to fit experimental anomalies.

Findings

Non-universal U(1)' models without flavor violation cannot fully explain B decay anomalies.

Such models can only modify BR(B+→K+νν¯) by about 10%.

Introducing lepton flavor violation allows these models to accommodate the data.

Abstract

In view of both the latest LHCb measurement of $R_{K^{(*)}}$ and the new $2.8\sigma$ deviation reported by Belle II on $B^{+}\to K^{+}\nu\bar{\nu}$ decays, we present a fit to the $B$ meson anomalies for various one and two dimensional hypothesis including complex Wilson coefficients. We show in a model-independent way that the generic non-universal $U(1)^{\prime}$ extensions of the SM, without flavour violation, fail to simultaneously fit those observables and corroborate that they can modify $\mathrm{BR}(B^{+}\to K^{+}\nu\bar{\nu})$ up to only a $10\%$. In view of this deficit, we propose a new way in which those models can accommodate the data at tree level by introducing lepton flavour violating couplings and non-diagonal elements of the charged lepton mixing matrix, with implications in future charged lepton flavour violation searches.