Search for Higgs boson decays into a pair of light bosons in the $bb\mu\mu$ final state in $pp$ collision at $\sqrt{s} = $13 TeV with the ATLAS detector

TL;DR

This paper reports a search for Higgs boson decays into a pair of light bosons that decay into $b$-quark and muon pairs, using 13 TeV proton-proton collision data from ATLAS, setting upper limits on such processes.

Contribution

It presents the first search for $H o aa o bb\,\mu\mu$ decays at 13 TeV with ATLAS, establishing new upper limits on the branching ratio and production cross-section.

Findings

No significant deviation from the Standard Model was observed.

Upper limits on the branching ratio range from $2\times 10^{-4}$ to $10^{-3}$.

Model-independent limits on cross-section times branching ratio range from 0.1 fb to 0.73 fb.

Abstract

A search for decays of the Higgs boson into a pair of new spin-zero particles, $H \to aa$, where the $a$-bosons decay into a $b$-quark pair and muon pair, is presented. The search uses 36.1 fb$^{-1}$ of proton-proton collision data at $\sqrt{s}=13$ TeV recorded by the ATLAS experiment at the LHC in 2015 and 2016. No significant deviation from the Standard Model prediction is observed. Upper limits at 95% confidence level are placed on the branching ratio $(\sigma_H / \sigma_{SM}) \times B(H\to aa\to bb\mu\mu)$, ranging from $2\times 10^{-4}$ to $10^{-3}$ in the $a$-boson mass range of 20-60 GeV. Model-independent limits are set on the visible production cross-section times the branching ratio to the $bb\mu\mu$ final state for new physics, $\sigma_{vis}(X) \times B(X\to bb\mu\mu)$, ranging from 0.1 fb to 0.73 fb for $m_{\mu\mu}$ between 18 and 62 GeV.