$U(1)_{B_3-L_2}$ Explanation of the Neutral Current $B-$Anomalies

TL;DR

This paper proposes a $U(1)_{B_3-L_2}$ gauge extension of the Standard Model to explain neutral current B-anomalies, predicting a TeV-scale Z' boson and flavon signals observable at colliders.

Contribution

It introduces a minimal $U(1)_{B_3-L_2}$ model that explains B-anomalies and predicts new particles with specific mass constraints, connecting flavor physics and collider phenomenology.

Findings

The model can explain B-anomalies within certain Z' mass ranges.

Current experimental constraints exclude Z' masses between 0.15 and 1.9 TeV.

Predicted flavonstrahlung signals could be observed at colliders.

Abstract

We investigate a speculative short-distance force, proposed to explain discrepancies observed between measurements of certain neutral current decays of $B$ hadrons and their Standard Model predictions. The force derives from a spontaneously broken, gauged $U(1)_{B_3-L_2}$ extension to the Standard Model, where the extra quantum numbers of Standard Model fields are given by third family baryon number minus second family lepton number. The only fields beyond those of the Standard Model are three right-handed neutrinos, a gauge field associated with $U(1)_{B_3-L_2}$ and a Standard Model singlet complex scalar which breaks $U(1)_{B_3-L_2}$, a `flavon'. This simple model, via interactions involving a TeV scale force-carrying $Z^\prime$ vector boson, can successfully explain the neutral current $B-$anomalies whilst accommodating other empirical constraints. In an ansatz for fermion mixing, a combination of up-to-date $B-$anomaly fits, LHC direct $Z^\prime$ search limits and other bounds rule out the domain 0.15 TeV$< M_{Z^\prime} <$ 1.9 TeV at the 95$\%$ confidence level. For more massive $Z^\prime$s, the model possesses a {\em flavonstrahlung}\ signal, where $pp$ collisions produce a $Z^\prime$ and a flavon, which subsequently decays into two Higgs bosons.