A search for the decay mode of the Higgs boson in Collisions at with the ATLAS detector

A search for the Zγ decay of the Higgs boson, with Z boson decays into pairs of electrons or muons is presented. The analysis uses proton–proton collision data at $\sqrt{s}$ = 13 TeV corresponding to an integrated luminosity of 139 fb$^{−1}$ recorded 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\to H\to Z\gamma $ is set at 3.6 times the Standard Model prediction while 2.6 times 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 ${2.0}_{-0.9}^{+1.0}$ where the statistical component of the uncertainty is dominant.