Measurement of the Higgs boson mass from the H→γγ and H→ZZ^∗→4ℓ channels with the ATLAS detector using 25 fb⁻¹ of pp collision data

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.

Detailed measurements of Higgs' boson properties are a part of strategy that will determine whether this recently discovered particle fits in the Standard Model of particle physics or represents a hint of new physics beyond this model.

Institute of Physics is a co-founder of the ATLAS experiment. Our staff has participated on development, construction and operation of path detectors and calorimeter. Both devices have played an important part in the Higgs boson discovery and are essential for detailed measurement of its parameters.

Four-lepton invariant mass spectrum measured by ATLAS experiment. Blue regions corresponds to the fitted Higgs boson signal, other colors represent Standard Model expectations without the presence of Higgs boson.

¹Fakultät für Mathematik und Physik, Albert-Ludwigs-Universität, Freiburg, Germany
²Institute of Physics, Academy of Sciences of the Czech Republic, Praha, Czech Republic.