A search for the dimuon decay of the Standard Model Higgs boson with the ATLAS detector

TL;DR

This study searches for the Higgs boson decaying into two muons using ATLAS data, finding a modest excess over background and setting limits close to Standard Model predictions.

Contribution

It provides the most recent search for Higgs to dimuon decay with the full Run 2 dataset, improving sensitivity and setting new upper limits.

Findings

Observed significance of 2.0 sigma for Higgs to dimuon decay

Upper limit on cross section times branching ratio is 2.2 times SM prediction

Best-fit signal strength parameter is 1.2 ± 0.6

Abstract

A search for the dimuon decay of the Standard Model (SM) Higgs boson is performed using data corresponding to an integrated luminosity of 139 fb$^{-1}$ collected with the ATLAS detector in Run2 $pp$ collisions at $\sqrt{s}=13$ TeV at the Large Hadron Collider. The observed (expected) significance over the background-only hypothesis for a Higgs boson with a mass of 125.09 GeV is $2.0\,\sigma$ ($1.7\,\sigma$). The observed upper limit on the cross section times branching ratio for $pp \to H \to \mu\mu$ is 2.2 times the SM prediction at 95% confidence level, while the expected limit on a $H \to \mu\mu$ signal assuming the absence (presence) of a SM signal is $1.1$ ($2.0$). The best-fit value of the signal strength parameter, defined as the ratio of the observed signal yield to the one expected in the SM, is $\mu = 1.2 \pm 0.6$.