Measurements of fiducial and differential cross sections for Higgs boson production in the diphoton decay channel at √s = 8 TeV with ATLAS

Measurements of fiducial and differential cross sections are presented for Higgs
boson production in proton-proton collisions at a centre-of-mass energy of √s = 8TeV. The
analysis is performed in the H-> yy decay channel using 20.3 fb−1 of data recorded by the
ATLAS experiment at the CERN Large Hadron Collider. The signal is extracted using a fit
to the diphoton invariant mass spectrum assuming that the width of the resonance is much
smaller than the experimental resolution. The signal yields are corrected for the effects of
detector inefficiency and resolution. The pp ->H ->yy fiducial cross section is measured to
be 43.2 ±9.4 (stat.) +3.2−2.9 (syst.) ±1.2 (lumi) fb for a Higgs boson of mass 125.4 GeV decaying
to two isolated photons that have transverse momentum greater than 35% and 25% of
the diphoton invariant mass and each with absolute pseudorapidity less than 2.37. Four
additional fiducial cross sections and two cross-section limits are presented in phase space
regions that test the theoretical modelling of different Higgs boson production mechanisms,
or are sensitive to physics beyond the Standard Model. Differential cross sections are also
presented, as a function of variables related to the diphoton kinematics and the jet activity
produced in the Higgs boson events. The observed spectra are statistically limited but
broadly in line with the theoretical expectations.