B meson anomalies and large B + → K + ν ν ¯ $$ {B}^{+}\to {K}^{+}\nu \overline{\nu} $$ in non-universal U(1) ′ models

Abstract

Abstract In view of both the latest LHCb measurement of R K ∗ $$ {R}_{K^{\left(\ast \right)}} $$ and the new 2.7σ deviation reported by Belle II on B + → K + ν ν ¯ $$ {B}^{+}\to {K}^{+}\nu \overline{\nu} $$ 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)′ extensions of the SM, without flavour violation, fail to simultaneously fit those observables and corroborate that they can modify BR B + → K + ν ν ¯ $$ \textrm{BR}\left({B}^{+}\to {K}^{+}\nu \overline{\nu}\right) $$ 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.

Keywords

• Semi-Leptonic Decays
• New Gauge Interactions
• Specific BSM Phenomenology
• Lepton Flavour Violation (charged)