Measurements of fiducial and differential cross sections for Higgs boson production in the diphoton decay channel at s = 8 $$ \sqrt{s}=8 $$ TeV with ATLAS

Abstract

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 = 8 TeV. The analysis is performed in the H → γγ 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 → γγ 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.

Searching for degenerate Higgs bosons

“…For ease of comparison, and even if more recent data are available [6,[14][15][16][17][18][19][20][21][22][23][24][25][26][27], the following numerical examples are carried out using the same signal strength matrix presented in Ref. [4], namely…”

NNLO QCD corrections to Higgs boson production at large transverse momentum

“…With more and more statistics collected by the experiments, differential measurements in kinematical variables will become increasingly precise, thereby allowing detailed tests of the underlying Standard Model theory. A first glimpse at the potential of these studies can already be gained from the LHC 8 TeV data, with ATLAS [3] and CMS [4] performing, among other observables, a first measurement of the transverse momentum distribution of the Higgs boson in the diphoton decay mode. An important discriminator between Higgs production modes is the production of hadronic jets in association with the Higgs boson, with first cross section measurements available [3,4] from the 8 TeV data set.…”

Higgs Boson Properties

“…[15][16][17][18][19][20][21] The black check marks indicate channels entering the combined signal and coupling strength measurements. 14 These channels are documented in the references given in the …”

“…15,16,18,19 ATLAS also combined the H → γγ and H → ZZ ( * ) → llll channels in a common fiducial volume. 17 Measurements using the H → W W ( * ) decay channel were also performed 20,21 but not considered in the following examples.…”

“…However, some sensitivity to the VBF production is also reached in the high p T and N jets = 2 part of the phase space, where dedicated measurements for VBF-related observables were done in the H → γγ analyses. 15,18 With increasing luminosity, the sensitivity to other production modes can be expected to increase.…”