Geneva (ISJ) ? Scientists at the European Organisation for Nuclear Research, CERN presented for the first time a combination of results on the mass of the Higgs boson, the most precise measurement as yet and the most precise measurements performed at the LHC (Large Hadron Collider, the particle accelerator) to date, said a press release by CERN.
?I?m delighted to see so many brilliant physicists from ATLAS and CMS joining forces for the very first time to obtain this important measurement at the LHC,? said CERN Director General Rolf Heuer.
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.
The Higgs boson decays into different particles. For this measurement, results on the two decay channels that best reveal the mass of the Higgs boson have been combined. These two decay channels are: the Higgs boson decaying to two photons; and the Higgs boson decaying to four leptons ? where the leptons are an electron or muon.
Each experiment has found a few hundred events in the Higgs to photons channel and a few tens in the Higgs to leptons channel, using the data collected at the LHC in 2011 and 2012 at centre-of-mass energies of 7 and 8 TeV.
?The Higgs Boson was discovered at the LHC in 2012 and the study of its properties has just begun. By sharing efforts between ATLAS and CMS, we are going to understand this fascinating particle in more detail and study its behaviour,? said CMS spokesperson Tiziano Camporesi.
?CMS and ATLAS 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.
The Standard Model does not predict the mass of the Higgs boson itself and therefore it must be measured experimentally. However, once supplied with a Higgs mass, the Standard Model does make predictions for all the other properties of the Higgs boson, which can then be tested by the experiments. This mass combination represents the first step towards a combination of other measurements of Higgs boson properties, which will involve also the other decays.
"While we are just getting ready to restart the LHC, it is admirable to notice the precision already achieved by the two experiments and the compatibility of their results. This is very promising for LHC Run 2,? said CERN Director of Research Sergio Bertolucci.
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. India has observer status in the scientific body.
Image courtesy: CERN