Improved separation of the Higgs boson signal from background in the high transverse momentum in the diphoton channel

The diphoton decay channel of the Higgs boson provides a clean experimental signature despite its small branching ratio. At high Higgs transverse momenta, the signal-to-background ratio improves considerably, though with lower statistics. This phenomenological study aims to enhance the separation of the Higgs signal from the diphoton background in this high pT regime using event-level observables. Using Monte Carlo samples enriched in high pT events, we examine variables such as the ratio of the leading to sub-leading photon transverse momenta and the diphoton invariant mass to assign event by event probabilities for being signal-like or background-like. In the longer term, this approach may be used to help distinguish between different Higgs production modes including gluon-gluon fusion (ggF), vector-boson fusion (VBF), and associated production (VH/ttH), providing a foundation for machine learning based approaches for high pT Higgs studies.