Search For Higgs Bosons Produced In Association With A High-Energy Photon Via Vector-Boson Fusion And Decaying To A Pair Of B-Quarks In The ATLAS Detector

Abstract

A search for Standard Model Higgs bosons produced in association with a high-energy photon and decaying to bb¯ is performed using 133 fb−1 of s=13 TeV pp collision data collected with the ATLAS detector at the Large Hadron Collider at CERN. The photon requirement reduces the multijet background, and the H→bb¯ decay is the dominant decay mode. Event selection requirements target events produced by vector-boson fusion, the dominant production mode in this channel. Several improvements enhance the search sensitivity compared to previous measurements. These improvements include better background modelling and characterization, the use of a neural-network classifier, and an updated signal extraction strategy adopting a direct binned-likelihood fit to the classifier output. With these improvements, the Higgs boson signal strength is measured to be 0.2 ± 0.7 relative to the Standard Model prediction. This corresponds to an observed significance of 0.3 standard deviations, compared to an expectation of 1.5 standard deviations assuming the Standard Model