On new physics contributions to the Higgs decay to Z gamma

Abstract

The authors thank Yi Chen, Kevin Earl, and Dylan Linthorne for helpful discussions. P.A.S is supported in part by the Ontario Graduate Scholarship (OGS). D.S. is supported in part by the Natural Sciences and Engineering Research Council of Canada (NSERC). The work of R.V.M. has been partially supported by the Ministry of Science and Innovation under grant number FPA2016-78220-C3-1-P (FEDER), SRA under grant PID2019106087GB-C22 (10.13039/501100011033), and by the Junta de Andalucia grants FQM 101, and A-FQM-211-UGR18 and P18-FR-4314 (FEDER). ; We explore models of new physics that can give rise to large (100% or more) enhancements to the rate of Higgs decay to Z gamma while still being consistent with other measurements. We show that this is impossible in simple models with one additional multiplet and also in well motivated models such as the MSSM and folded SUSY. We do find models with several multiplets that carry electroweak charge where such an enhancement is possible, but they require destructive interference effects. We also show that kinematic measurements in Higgs decay to four leptons can be sensitive to such models. Finally we explore the sensitivity of four lepton measurements to supersymmetric models and find that while the measurement is difficult with the high luminosity LHC, it may be possible with a future high energy hadron collider. ; Ontario Graduate Scholarship ; Natural Sciences and Engineering Research Council of Canada (NSERC) ; Spanish Government FPA2016-78220-C3-1-P ; Sugar Research Australia PID2019106087GB-C22 (10.13039/501100011033) ; Junta de Andalucia FQM 101 A-FQM-211-UGR18 P18-FR-4314