Muon $(g-2)$ and Flavor Puzzles in the $U(1)^{}_{X}$-gauged Leptoquark Model

TL;DR

This paper proposes a unified model with a leptoquark and a new gauge symmetry to explain muon g-2, flavor anomalies, and flavor mixing, aligning with recent experimental results.

Contribution

It introduces a novel $U(1)_X$ gauge symmetry combined with an $S_1$ leptoquark to simultaneously address multiple flavor anomalies and muon g-2.

Findings

Explains muon g-2 discrepancy with the leptoquark.

Accounts for $R_{K^{(*)}}$ and $R_{D^{(*)}}$ anomalies via $Z'$ gauge boson.

Generates flavor mixing patterns through spontaneous symmetry breaking.

Abstract

We present an economical model where an $S^{}_1$ leptoquark and an anomaly-free $U(1)^{}_X$ gauge symmetry with $X = B^{}_3-2L^{}_\mu/3-L^{}_\tau/3$ are introduced, to account for the muon anomalous magnetic moment $a^{}_\mu \equiv (g^{}_\mu-2)$ and flavor puzzles including $R^{}_{K^{(\ast)_{}}}$ and $R^{}_{D^{(\ast)_{}}}$ anomalies together with quark and lepton flavor mixing. The $Z^\prime_{}$ gauge boson associated with the $U(1)^{}_X$ symmetry is responsible for the $R^{}_{K^{(\ast)_{}}}$ anomaly. Meanwhile, the specific flavor mixing patterns of quarks and leptons can be generated after the spontaneous breakdown of the $U(1)^{}_X$ gauge symmetry via the Froggatt-Nielsen mechanism. The $S^{}_1$ leptoquark which is also charged under the $U(1)^{}_X$ gauge symmetry can simultaneously explain the latest muon $(g-2)$ result and the $R^{}_{D^{(\ast)_{}}}$ anomaly. In addition, we also discuss several other experimental constraints on our model.