Combined Higgs measurements ATLAS and CMS jointly published in Physical Review Letters
The renowned journal Physical Review Letters recently published the first combined article by the ATLAS and CMS experiments at the Large Hadron Collider (LHC) in Geneva, describing the measurements of the mass of the Higgs boson by both collaborations.
The University of Amsterdam contributes to the ATLAS experiment at the LHC through Nikhef, the National Institute for Subatomic Physics in Amsterdam. The recently published result, obtained by joining the analyses of the decay of Higgs particles into either two Z bosons (‘ZZ’) or two photons (‘gamma gamma’) provides a highly accurate estimate of the mass of the Higgs boson: 125.09 ± 0.24 GeV: an uncertainty of only 0.2%.The publication also shows that the independent measurements of the Higgs boson mass are consistent, both among the two experiments and among the ZZ and gamma gamma decay channels studied. The measurement is limited by the finite size of the data set, and will thus be improved significantly with the new data expected from Run 2 of the LHC, which is about to start.
The Higgs mass is an important parameter within the Standard Model for subatomic physics. An accurate measurement of the Higgs mass and other observables allows for a thorough consistency test for the Standard Model. New physics can possibly lead to quantum corrections that show up as deviations from the Standard Model expectations.
The value found for the Higgs mass turns out to be quite a special one: this value brings our universe in a metastable vacuum state close to a phase transition. To be continued…
G. Aad et al. (ATLAS Collaboration, CMS Collaboration), Combined Measurement of the Higgs Boson Mass in pp Collisions at √s=7 and 8 TeV with the ATLAS and CMS Experiments, Physical Review Letters 114, 191803 (2015).