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

<p>Searches are performed for resonant and nonresonant Higgs boson pair production in the <inline-formula><mml:math display="inline"><mml:mi>γ</mml:mi><mml:mi>γ</mml:mi><mml:mi>b</mml:mi><mml:mover accent="true"><mml:mi>b</mml:mi><mml:mo accent="true" stretchy="false">¯</mml:mo></mml:mover></mml:math></inline-formula> final state using <inline-formula><mml:math display="inline"><mml:mrow><mml:mn>20</mml:mn><mml:mtext> </mml:mtext><mml:mtext> </mml:mtext><mml:msup><mml:mrow><mml:mi>fb</mml:mi></mml:mrow><mml:mrow><mml:mo>-</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math></inline-formula> 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 nonresonant 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 <inline-formula><mml:math display="inline"><mml:mi>X</mml:mi><mml:mo stretchy="false">→</mml:mo><mml:mi>h</mml:mi><mml:mi>h</mml:mi></mml:math></inline-formula> resonance ranges between 0.7 and 3.5 pb as a function of the resonance mass.</p>