A search for the Zγ decay mode of the Higgs boson in pp collisions at s=13 TeV with the ATLAS detector

Abstract

A search for the Zγdecay of the Higgs boson, with Zboson decays into pairs of electrons or muons is presented. The analysis uses proton–proton collision data at √s= 13TeV corresponding to an integrated luminosity of 139fb−1recorded by the ATLAS detector at the Large Hadron Collider. The observed data are consistent with the expected background with a p-value of 1.3%. An upper limit at 95% confidence level on the production cross-section times the branching ratio for pp →H→Zγis set at 3.6times the Standard Model prediction while 2.6times is expected in the presence of the Standard Model Higgs boson. The best-fit value for the signal yield normalised to the Standard Model prediction is 2.0+1.0−0.9where the statistical component of the uncertainty is dominant.