Shedding light on dark matter with recent muon $(g-2)$ and Higgs exotic decay measurements

TL;DR

This paper explores potential explanations for recent experimental anomalies in muon magnetic moment measurements and Higgs exotic decays, proposing a dark matter model with a pseudoscalar mediator and vector-like muon lepton.

Contribution

It introduces a simplified dark matter model with a pseudoscalar mediator and vector-like muon lepton to simultaneously explain the observed anomalies.

Findings

The model can account for the $(g-2)_4$ deviation.

It provides a possible explanation for the Higgs decay excess.

The proposed particles are consistent with current null dark matter detection results.

Abstract

Recently, we have witnessed two hints of physics beyond the standard model: A 3.3$\sigma$ local excess ($M_{A_0} = 52$ GeV) in the search for $H_0\to A_0 A_0\to b\bar{b}\mu^{+}\mu^{-}$ and a 4.2$\sigma$ deviation from the SM prediction in the $(g-2)_\mu$ measurement. The first excess was found by the ATLAS Collaboration using 139 fb$^{-1}$ data at $\sqrt{s}=13$ TeV. The second deviation is a combination of the results from the Brookhaven E821 and the recently reported Fermilab E989 experiment. We attempt to explain these deviations in terms of a renormalizable simplified dark matter model. Inspired by the null signal result from dark matter (DM) direct detection, we interpret the possible new particle, $A_0$, as a pseudoscalar mediator connecting DM and the standard model. On the other hand, a new vector-like muon lepton can explain these two excesses at the same time while contributiong to the DM phenomenology.