Complete Vector-like Fourth Family with $\mathrm{U(1)}^\prime$: A Global Analysis

TL;DR

This paper analyzes a Standard Model extension featuring a complete vector-like fourth generation and a new U(1)' gauge symmetry, aiming to explain muon anomalies through a comprehensive global fit of 98 observables.

Contribution

It provides the first detailed global analysis of a vector-like fourth family with U(1)' symmetry, demonstrating its potential to address muon anomalies and predicting accessible new particles.

Findings

Many model points fit data with chi-squared per degree of freedom ≤ 1

New heavy Z' and vector-like leptons are typically below 1 TeV

Model can simultaneously explain muon g-2 and B decay anomalies

Abstract

In this paper we present an in-depth analysis of a recently proposed Standard Model extension with a complete fourth generation of quarks and leptons, which are vector-like with respect to the Standard Model gauge group and charged under a new spontaneously broken vector-like $\mathrm{U(1)^\prime}$ gauge symmetry. The model is designed to explain the known muon anomalies, i.e. the observed deviations from Standard Model predictions in the anomalous magnetic moment of the muon, $\Delta a_\mu$, and in $b \rightarrow s \ell^+ \ell^-$ processes. We perform a global $\chi^2$ analysis of the data with $65$ model parameters and including $98$ observables. We find many points with $\chi^2$ per degree of freedom $\leq 1$. The vector-like leptons and the new heavy $Z^\prime$ are typically much lighter than a TeV and would, thus, be eminently visible at the HL-LHC.