Evidence for the Higgs Boson Decay to a Z Boson and a Photon at the LHC

Abstract

The first evidence for the Higgs boson decay to a <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>Z</a:mi></a:math> 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 datasets collected at the CERN Large Hadron Collider (LHC) from 2015 to 2018. These correspond to integrated luminosities of around <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mrow><c:mn>140</c:mn><c:mtext> </c:mtext><c:mtext> </c:mtext><c:msup><c:mrow><c:mi>fb</c:mi></c:mrow><c:mrow><c:mo>−</c:mo><c:mn>1</c:mn></c:mrow></c:msup></c:mrow></c:math> for each experiment, at a center-of-mass energy of 13 TeV. The measured signal yield is <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:mrow><e:mn>2.2</e:mn><e:mo>±</e:mo><e:mn>0.7</e:mn></e:mrow></e:math> times the standard model prediction, and agrees with the theoretical expectation within 1.9 standard deviations. © 2024 CERN, for the ATLAS and CMSs Collaboration 2024 CERN