Self-interacting dark matter and muon $g-2$ in a gauged U$(1)_{L_{\mu} - L_{\tau}}$ model

TL;DR

This paper proposes a gauged U(1)_{L_{μ}-L_{τ}} model that explains the muon g-2 anomaly and provides self-interacting dark matter with velocity-dependent cross sections, consistent with astrophysical and cosmological constraints.

Contribution

It introduces a novel U(1)_{L_{μ}-L_{τ}} extension with a dark matter candidate and a light Higgs boson, linking muon g-2 and dark matter self-interactions in a unified framework.

Findings

The model explains muon g-2 within experimental bounds.

Dark matter self-interactions are velocity-dependent and consistent with galaxy observations.

Astrophysical and cosmological constraints are satisfied due to decay channels of the light mediator.

Abstract

We construct a self-interacting dark matter model that could simultaneously explain the observed muon anomalous magnetic moment. It is based on a gauged U$(1)_{L_{\mu} - L_{\tau}}$ extension of the standard model, where we introduce a vector-like pair of fermions as the dark matter candidate and a new Higgs boson to break the symmetry. The new gauge boson has a sizable contribution to muon $(g-2)$, while being consistent with other experimental constraints. The U$(1)_{L_{\mu} - L_{\tau}}$ Higgs boson acts as a light force carrier, mediating dark matter self-interactions with a velocity-dependent cross section. It is large enough in galaxies to thermalize the inner halo and explain the diverse rotation curves and diminishes towards galaxy clusters. Since the light mediator dominantly decays to the U$(1)_{L_{\mu} - L_{\tau}}$ gauge boson and neutrinos, the astrophysical and cosmological constraints are weak. We study the thermal evolution of the model in the early Universe and derive a lower bound on the gauge boson mass.