Record precision on the measurement of the Higgs mass
"At this Summer's Lepton Photon Conference the ATLAS collaboration reported a news result for the Higgs boson mass: 125.11 GeV with an uncertainty of 0.11 GeV. With a precision of 0.09%, this is the most precise measurement yet of this fundamental parameter."
The mass of the Higgs boson is not predicted by the Standard Model (SM) and must therefore be determined by experimental measurement. Its value governs the strengths of the interactions of the Higgs boson. A precise knowledge of this parameter is key to accurate theoretical calculations which, in turn, allow us to confront measurements of the Higgs boson’s properties with SM predictions. The Higgs mass is also a crucial parameter driving the evolution and the stability of the Universe’s vacuum.
The ATLAS and CMS collaborations have been making ever more precise measurements of the Higgs boson’s mass since the particle’s discovery. The new ATLAS result combines a new mass measurement based on an analysis of the particle’s decay into two high-energy photons and an earlier measurement based on a study of its decay into four leptons.
While the analysis of the full ATLAS Run 2 data set reduced the statistical uncertainty by a factor of two, a very detailed understanding of the data allowed to decrease the systematic uncertainty by almost a factor of four.