WIREDGOV

At a research conference in Italy yesterday CERN experiments ATLAS and CMS presented for the first time a combination of their results on the mass of the Higgs boson. The combined mass of the Higgs boson is mH = 125.09 ± 0.24 (0.21 stat. ± 0.11 syst.), which corresponds to a measurement precision of better than 0.2%. It is the most precise measurement of the Higgs boson mass yet and among the most precise measurements performed at the LHC to date.

In the LHC’s proton-proton collisions, the Higgs boson decays into various different particles.  For this measurement, results on the two decay channels that best reveal the mass of the Higgs boson (H->γγ and H->ZZ*->llll) have been examined. The ATLAS and CMS teams have sifted through data from approximately 4000 trillion proton-proton collisions collected at the LHC in 2011 and 2012. Each experiment has found a few hundred events in the H->γγ channel and a few tens in H->ZZ*->llll.  The two collaborations worked together and reviewed the analyses and their combination.

The Higgs boson is an essential ingredient of the Standard Model of particle physics, the theory that describes all known elementary particles and their interactions. The Brout-Englert-Higgs mechanism, through which the existence of the Higgs boson was predicted, is believed to give mass to all elementary particles.

“ATLAS and CMS use different detector technologies and different detailed analyses to determine the Higgs mass. The measurements made by the experiments are quite consistent, and we have learnt a lot by working together, which stands us in good stead for further combinations.” said ATLAS spokesperson Dave Charlton, University of Birmingham.

"The discovery of the Higgs boson in 2012 was a fundamental breakthrough, and we've followed up on that by combining the ATLAS and CMS capabilities in this measurement. The upgraded LHC will allow us to go even further together later this year and to explore the properties of the new particle in detail" said Dave Newbold of the CMS experiment and University of Bristol.

This result was achieved by bringing together physicists of the ATLAS and CMS collaborations, representing together more than 5,000 scientists from over 50 different countries.

Visit the CERN website to learn more about this latest finding.

STFC & CERN

The Science and Technology Facilities Council (STFC) co-ordinates and manages the UK’s involvement and subscription with CERN.

The UK’s influence on both CERN Council and CERN Finance Committee is coordinated through the UK Committee on CERN (UKCC). UK membership of CERN gives our physicists and engineers access to the experiments and allows UK industry to bid for contracts, UK nationals to compete for jobs and research positions at CERN, and UK schools and teachers to visit. UK scientists hold many key roles at CERN.

Firms in the UK win contracts for work at CERN worth millions of pounds each year. The impact of winning contracts is often even greater as it enables companies to win business elsewhere.