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

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 $b\to s{\ell }^{+}{\ell }^{-}$ 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 $\le 1$. 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.

Comments: 80 pages, 9 figures and 21 tables