A ’double Z’ event observed at the heart of ATLAS: physicists believe Higgs boson decay would look like this, producing two Z bosons
Liverpool physicists celebrate Higgs success
Liverpool physicists who have played a major role in the search for the Higgs boson particle, are celebrating following new results which appear to confirm the existence of the Higgs.
The results were announced at a seminar at CERN , the European Organisation for Nuclear Research, which is home to the Large Hadron Collider (LHC). Scientists confirmed that a new particle had been observed in two LHC experiments, ATLAS and CMS, which appears to be the fabled Higgs Boson.
The LHC - the world’s highest energy particle accelerator - works by accelerating two beams of protons to almost the speed of light. The protons collide together 40 million times a second, recreating the conditions of the Universe immediately after the Big Bang, and enabling scientists to reconstruct fundamental particles produced at that time.
Results presented by the LHC experiments last December and by the Tevatron accelerator in Illinois earlier this week provided tantalising but inconclusive indications of a new particle with a mass of about 125 times that of a proton. After painstaking analysis of the all the data obtained so far, scientists have confirmed the observation of this new particle with a statistical significance which exceeds the golden ’5 sigma’ standard above which they can announce a discovery.
Professor Themis Bowcock, Head of Particle Physics at the University, said: "This is cast-iron proof that a new particle has been discovered. It looks like the Higgs.
"Half a century after it was first proposed, and after a monumental effort by generations of physicists around the world, the discovery of the Higgs represents a major breakthrough in our fundamental understanding of nature. For physicists, this is the equivalent of Columbus discovering America."
Liverpool scientists have been major contributors to the LHC’s ATLAS experiment from the start. One of the tracking detectors that sits at the heart of ATLAS was constructed at the University’s Semiconductor Detector Centre. Liverpool physicists also contribute to a broad particle physics research program carried out by the experiment and a team led by Andrew Mehta and Joost Vossebeld has been responsible for results produced in several Higgs search channels. A statistical combination of the results in several search channels is the basis of the results reported today.
"Although we knew the ATLAS results, none of us had seen the results from the other LHC experiment, CMS", said Helen Hayward, who also works on Higgs searches in ATLAS. "Once it became clear that the results of CMS confirmed those of ATLAS, there was little doubt that a real breakthrough had been achieved."
Although a formal discovery can only be claimed when both experiments submit the results for publication in a scientific journal, most likely by the end of July, there is no doubt that the Higgs particle has finally been pinned down. In the months and years to come physicists at the LHC will collect more data and try to establish the properties of the new particle.
Members of the Liverpool ATLAS group (left to right): Carl Gwilliam, Joost Vossebeld, Andrew Mehta and Matthew Jackson
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