Z' models for the LHCb and g-2 muon anomalies

TL;DR

This paper analyzes Z' models as explanations for LHCb B decay anomalies and muon g-2, showing they are highly constrained but can be viable with specific coupling suppressions or dark matter decays.

Contribution

It introduces a simplified framework with a TeV-scale Z' that can explain both LHCb anomalies and muon g-2, considering various experimental constraints.

Findings

Z' models are tightly constrained by multiple experimental data.

Suppression of Z' couplings to electrons and light quarks can evade constraints.

A Z' decaying into dark matter can still explain anomalies.

Abstract

We revisit a class of Z' explanations of the anomalies found by the LHCb collaboration in $B$ decays, and show that the scenario is tightly constrained by a combination of constraints: (i) LHC searches for di-muon resonances, (ii) pertubativity of the Z' couplings; (iii) the $B_s$ mass difference, and (iv) and electro-weak precision data. Solutions are found by suppressing the Z' coupling to electrons and to light quarks and/or by allowing for a Z' decay width into dark matter. We also present a simplified framework where a TeV-scale Z' gauge boson that couples to standard leptons as well as to new heavy vector-like leptons, can simultaneously accommodate the LHCb anomalies and the muon g-2 anomaly.