Measurement of Higgs boson production in the diphoton decay channel inppcollisions at center-of-mass energies of 7 and 8 TeV with the ATLAS detector

Abstract

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 ¼ 7 TeV and 20.3 fb −1 at ffiffi ffi s p ¼ 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 μ ¼ 1.17 AE 0.27 at the value of the Higgs boson mass measured by ATLAS, m H ¼ 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 μ ggF ¼ 1.32 AE 0.38, μ VBF ¼ 0.8 AE 0.7, μ WH ¼ 1.0 AE 1.6, μ ZH ¼ 0.1 þ3.7 −0.1 , and μ ttH ¼ 1.6 þ2.7 −1.8 , for Higgs boson production through gluon fusion, vector-boson fusion, and in association with a W or Z boson or a top-quark pair, respectively. Compared with the previously published ATLAS analysis, the results reported here also benefit from a new energy calibration procedure for photons and the subsequent reduction of the systematic uncertainty on the diphoton mass resolution. No significant deviations from the predictions of the Standard Model are found.

Effects of two inert scalar doublets on Higgs boson interactions and the electroweak phase transition

“…Here we address some of the potential implications for our scenario of interest. Especially, the existing experimental information on the possible Higgs decay into invisible/nonstandard final states [26][27][28][29][30] and on the observed h → γγ mode [24,31] can supply further restrictions on the inert scalars.…”

“…For the γγ signal strengths, the ATLAS and CMS Collaborations measured σ=σ SM ¼ 1.17 AE 0.27 [31] and 1.13 AE 0.24 [24], respectively. These numbers need to be respected by the ratio of Γðh → γγÞ to its SM value,…”

Boosted Higgs bosons from chromomagneticb’s:bb¯hat high luminosity

“…II A and II B, the SM-O ghd interference is not suppressed by m b , and it is possible to enhance the O ghd effects by looking at regions of phase space where ffiffi f s p is large. The Higgs-plus-jets channel with the tightest constraint on new physics contributions is the diphoton decay mode, hðγγÞ þ jj; specifically, the rate in this channel in any extension of the SM relative to the SM-the signal strength μ collider -is restricted to 0.8 AE 0.7 by ATLAS [76], 3 and μ collider hjj ¼ 1.11 þ0.32 −0.30 by CMS [77]. Since O ghd has a different structure than the SM, we do not expect SM and "SM þ O ghd " events to have the same cut acceptance.…”

Predictions for the Isolated Prompt Photon Production at the LHC ats= 13 TeV

“…The associated production of prompt photons and heavy quarks, where the heavy quarks are either charm or bottom, can also provide a powerful tool for searching the intrinsic heavy quark components of the nucleon [50][51][52]. Moreover, a better understanding of prompt photon production is essential to have accurate QCD predictions for physical processes for which the prompt photons represent an important background such as diphoton decays of the Higgs boson [53][54][55][56].…”