Search for Higgs boson decays into a pair of light bosons in the bbμμ final state in pp collision at √s = 13 TeV with the ATLAS detector

Abstract

A search for decays of the Higgs boson into a pair of new spin-zero particles, H→aa, where the a-bosons decay into a b-quark pair and a muon pair, is presented. The search uses 36.1fb⁻¹ of proton–proton collision data at √s = 13 TeVrecorded 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 (σH/σSM) ×B(H→aa →bbμμ), ranging from 1.2 ×10⁻⁴ to 8.4 ×10⁻⁴ 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 bbμμfinal state for new physics, σvis(X) ×B(X→bbμμ), ranging from 0.1fb to 0.73fb for mμμbetween 18 and 62GeV.