The hunt for the most elusive subatomic particle of them all might finally caught its quarry, as the European Organisation for Nuclear Research (CERN), the world’s largest particle physics laboratory, said on July 4 that its experiments at the large hadron collider (LHC) have found “clear signs of a new particle” consistent with the predicted Higgs boson.
Occasionally referred to as “the god particle”, the Higgs boson is the theoretical elementary particle that is the key component of the mechanism that gives other sub-atomic particles their mass.
“The results are preliminary but the 5 sigma signal at around 125 GeV we’re seeing is dramatic. This is indeed a new particle. We know it must be a boson and it’s the heaviest boson ever found,” CMS experiment spokesperson Joe Incandela said in the CERN statement.
In simple terms, 5-sigma is the highest degree of certainty used by physicists to describe observed phenomena and the ability to replicate them – the probability of that is in excess of 99.999 per cent.
The large mass of the newly-discovered particle, 125 billion electronVolts (GeV), required a very large particle accelerator to be observed, and the hunt for the Higgs boson, first predicted in the 1960s, was one of the reasons for CERN to build the large hadron collider.
The results, presented on the same day at a seminar in Geneva and a major particle physics conference in Melbourne, were labelled preliminary, meaning more work would be needed to confirm the findings, based on data collected in 2011 and 2012, with the 2012 data still under analysis.
Publication of the analyses shown on July 4 was expected at the end of July, CERN said. A more complete picture was expected to emerge later this year after the LHC provides the experiments with more data.
“It’s hard not to get excited by these results,” CERN research director Sergio Bertolucci said. “We stated last year that in 2012 we would either find a new Higgs-like particle or exclude the existence of the Standard Model Higgs. With all the necessary caution, it looks to me that we are at a branching point: the observation of this new particle indicates the path for the future towards a more detailed understanding of what we’re seeing in the data.”
CERN’s next step will be to determine the precise nature of the particle and “its significance for our understanding of the universe”.
British theoretical physicist Peter Higgs (83), after whom the particle is named, was in attendance in Geneva. “For me it’s a really incredible thing that it’s happened in my lifetime,” he said, as quoted by The Guardian, congratulating everyone involved in what he described as a “tremendous achievement”.
(Illustration of the cross section of an large hadron collider dipole in the tunnel by CERN)