Evidence for the Higgs boson decay to a $Z$ boson and a photon at the LHC

TL;DR

This paper reports the first evidence of the Higgs boson decaying into a Z boson and a photon, based on combined data from ATLAS and CMS at the LHC, with a significance of 3.4 sigma.

Contribution

It provides the first experimental evidence for the Higgs decay to Z gamma, combining results from two major experiments at the LHC.

Findings

Significance of 3.4 standard deviations for the decay

Measured signal yield is 2.2±0.7 times the Standard Model prediction

Result consistent with the Standard Model within 1.9 standard deviations

Abstract

The first evidence for the Higgs boson decay to a $Z$ boson and a photon is presented, with a statistical significance of 3.4 standard deviations. The result is derived from a combined analysis of the searches performed by the ATLAS and CMS Collaborations with proton-proton collision data sets collected at the CERN Large Hadron Collider (LHC) from 2015 to 2018. These correspond to integrated luminosities of around 140 fb$^{-1}$ for each experiment, at a center-of-mass energy of 13 TeV. The measured signal yield is $2.2\pm0.7$ times the Standard Model prediction, and agrees with the theoretical expectation within 1.9 standard deviations.