Abstract
With pp collision data sample recorded by the ATLAS experiment at the CERN Large Hadron Collider at center-of-mass energies of 7 TeV and 8 TeV, corresponding to an integrated luminosity of 25 fb-1, an improved measurement of the mass of the Higgs boson is derived from a combined fit to the decay channels H→γγ and H→ZZ⁎→4l with improved energy-scale calibrations for photons, electrons and muons as well as other analysis improvements. It is mH=125.36±0.37(stat)±0.18(syst) GeV. Furthermore, measurement of fiducial and differential cross sections are presented in the H→γγ decay channel using only the 8 TeV data sample with a luminosity of 20.3fb-1. The observed spectra are statistically limited but broadly in line with the theoretical expectations.
Highlights
In 2012, the ATLAS and CMS collaborations announced a new particle [1, 2] in the search for the Standard Model (SM) Higgs boson [3, 4] at the CERN Large Hadron Collider
The Higgs mass is not predicted in the SM, which is important for precise calculations of electroweak observables including the production and decay properties of the Higgs boson, as well as the coupling structure of the SM Higgs boson, etc
After correcting for modifications of the data taking conditions with time, the stability of the LAr calorimeter response is at the level of 0.05% and the residual non-uniformal is at the level of 0.7% or better
Summary
In 2012, the ATLAS and CMS collaborations announced a new particle [1, 2] in the search for the Standard Model (SM) Higgs boson [3, 4] at the CERN Large Hadron Collider. The latest major improvement includes energy-scale calibrations and photon PID efficiency measurement. The achieved calibration accuracy for electrons from Z decays is typically 0.05% in most of the detector acceptance, rising to 0.2% in regions with large amounts of passive material; 0.2% to 1% for electrons with a transverse energy of 10 GeV, and on average of 0.3% for photons. There is a combination of three different methods of measurements of Z → llγ decays, extrapolation from electron in Z → ee decays, and Matrix methods based on photon purity, the PID uncertainty is at the level of 1% as shown in Fig. 2 [7]
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