Search For Higgs Boson Pair Production in the $\gamma\gamma b\bar{b}$ Final State using $pp$ Collision Data at $\sqrt{s}=8$ TeV from the ATLAS Detector

TL;DR

This paper reports on a search for Higgs boson pair production in proton-proton collisions at 8 TeV using the ATLAS detector, setting upper limits on production cross sections and observing a modest excess of events.

Contribution

The study provides the first limits on Higgs pair production in the $\,\gamma\gamma b\bar{b}$ final state at 8 TeV, including both resonant and non-resonant scenarios.

Findings

Set a 95% CL upper limit of 2.2 pb on non-resonant production

Observed a modest excess with 2.4 sigma significance

Limits on narrow resonance production range from 0.7 to 3.5 pb

Abstract

Searches are performed for resonant and non-resonant Higgs boson pair production in the $\gamma\gamma b\bar{b}$ final state using 20 fb$^{-1}$ of proton-proton collisions at a center-of-mass energy of 8 TeV recorded with the ATLAS detector at the CERN Large Hadron Collider. A 95% confidence level upper limit on the cross section times branching ratio of non-resonant production is set at 2.2 pb, while the expected limit is 1.0 pb. The difference derives from a modest excess of events, corresponding to 2.4 standard deviations from the background-only hypothesis. The limit observed in the search for a narrow $X \to hh$ resonance ranges between 0.7 and 3.5 pb as a function of the resonance mass.