Measurement of Higgs boson production in the diphoton decay channel in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>p</mml:mi><mml:mi>p</mml:mi></mml:math>collisions at center-of-mass energies of 7 and 8 TeV with the ATLAS detector

A measurement of the production processes of the recently discovered Higgs boson is performed in the two-photon final state using 4.5 fb -1 of proton-proton collisions data at ffiffi ffi s p 7 TeV and 20.3 fb -1 at ffiffi ffi s p 8 TeV collected by the ATLAS detector at the Large Hadron Collider. The number of observed Higgs boson decays to diphotons divided by the corresponding Standard Model prediction, called the signal strength, is found to be 1.17 AE 0.27 at the value of the Higgs boson mass measured by ATLAS, m H 125.4 GeV. The analysis is optimized to measure the signal strengths for individual Higgs boson production processes at this value of m H . They are found to be