Abstract
An improved measurement of the mass of the Higgs boson is derived from a combined fit to the reconstructed invariant mass spectra of the decay channels H→γγ and H→ZZ*→4ℓ. The analysis uses the 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. The measured value of the Higgs boson mass is mH=125.36±0.37(stat)±0.18(syst) GeV. This result is based on improved energy-scale calibrations for photons, electrons, and muons as well as other analysis improvements, and supersedes the previous result from ATLAS. Upper limits on the total width of the Higgs boson are derived from fits to the invariant mass spectra of the H→γγ and H→ZZ*→4ℓ decay channels.2 MoreReceived 17 June 2014DOI:https://doi.org/10.1103/PhysRevD.90.052004This article is available under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.© 2014 CERN, for the ATLAS Collaboration
Highlights
In 2012, the ATLAS and CMS collaborations published the discovery of a new particle [1,2] in the search for the Standard Model (SM) Higgs boson [3,4,5,6,7,8] at the CERN Large Hadron Collider (LHC) [9]
(v) Uncertainty in the modeling of the lateral shower shape: differences between data and simulation for the lateral development of electromagnetic showers contribute to the uncertainty on the energy scale if they depend on energy or particle type
The parameters of the functional form used to generate these pseudo-experiments are determined from the data. These pseudo-experiments are fitted using the nominal background model. This procedure leads to an uncertainty on the mass measurement between 0.01% and 0.05% depending on the category, and smaller than the uncertainties derived from the baseline method using the large sample of simulated background events
Summary
In 2012, the ATLAS and CMS collaborations published the discovery of a new particle [1,2] in the search for the Standard Model (SM) Higgs boson [3,4,5,6,7,8] at the CERN Large Hadron Collider (LHC) [9]. The measurement of the Higgs boson mass is updated in this work with improved analyses of the two channels H → γγ and H → ZZÃ → 4l, as described in Secs. The H → γγ channel profits from an improved calibration of the energy measurements of electron and photon candidates, which results in a sizable reduction of the systematic uncertainties on their energy scales. In the H → ZZÃ → 4l channel both the expected statistical uncertainty and the systematic uncertainty on the mass measurement have been reduced with respect to the previous publication. IV and V a brief description of the analyses used to measure the Higgs boson mass in the H → γγ and H → ZZÃ → 4l channels is presented, with emphasis on the improvements with respect to the analysis published in Ref. The range for electrons from H → ZZÃ → 4l decays is from 7 GeV to about 50 GeV
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