Eur. Phys. J. C (2022) 82: 480
https://doi.org/10.1140/epjc/s10052-022-10437-3

Regular Article - Theoretical Physics

Explaining lepton-flavor non-universality and self-interacting dark matter with $L_{\mu }-L_{\tau }$

Department of Physics, University of Virginia, 22904-4714, Charlottesville, VA, USA

^b wtd8kz@virginia.edu

Received: 8 March 2022
Accepted: 13 May 2022
Published online: 25 May 2022

Abstract

Experimental hints for lepton-flavor universality violation in the muon’s magnetic moment as well as neutral- and charged-current B-meson decays require Standard-Model extensions by particles such as leptoquarks that generically lead to unacceptably fast rates of charged lepton flavor violation and proton decay. We propose a model based on a gauged $U{(1)}_{L_{\mu }-L_{\tau }}$ that eliminates all these unwanted decays by symmetry rather than finetuning and efficiently explains ${(g-2)}_{\mu }$, $R_{K^{(\ast )}}$, $R_{D^{(\ast )}}$, and neutrino masses. The $U{(1)}_{L_{\mu }-L_{\tau }}$ furthermore acts as a stabilizing symmetry for dark matter and the light $Z^{\prime }$ gauge boson mediates velocity-dependent dark-matter self-interactions that resolve the small-scale structure problems. Lastly, even the Hubble tension can be ameliorated via the light $Z^{\prime }$ contribution to the relativistic degrees of freedom.