A "Vector-like chiral" fourth family to explain muon anomalies

TL;DR

This paper proposes a string theory-motivated, UV-complete model with a vector-like fourth family that explains muon g-2 and B-meson anomalies without conflicting with existing data, predicting new particles at the TeV scale.

Contribution

It introduces a novel vector-like fourth family model with a new U(1) gauge symmetry that simultaneously addresses multiple flavor anomalies and is compatible with GUT and string theory.

Findings

Explains muon g-2 and B-meson anomalies simultaneously.

Predicts TeV-scale VL quarks, leptons, and Z' boson.

Foresees observable tau decays in future experiments.

Abstract

The Standard Model (SM) is amended by one generation of quarks and leptons which are vector-like (VL) under the SM gauge group but chiral with respect to a new $\mathrm{U}(1)_{3-4}$ gauge symmetry. We show that this model can simultaneously explain the deviation of the muon $g-2$ as well as the observed anomalies in $b\rightarrow s\mu^+\mu^-$ transitions without conflicting with the data on Higgs decays, lepton flavor violation, or $B_s-\bar{B}_s$ mixing. The model is string theory motivated and GUT compatible, i.e. UV complete, and fits the data predicting VL quarks, leptons and a massive $Z'$ at the $\mathrm{TeV}$ scale, as well as $\tau\to3\mu$ and $\tau\to\mu\gamma$ within reach of future experiments. The Higgs couplings to SM generations are automatically aligned in flavor space.