US physicists see 'strong hints' of elusive Higgs particle

US-based physicists Monday reported finding strong hints of the Higgs boson, the elusive particle that is believed to give objects mass, but said European data is needed to confirm any potential discovery. If physicists can confirm the existence of the Higgs boson, the last missing piece in the standard model of physics, the announcement would rank among the most important scientific breakthroughs of the last century. The findings from Fermi National Accelerator Laboratory (Fermilab) in the midwestern US state of Illinois, will be followed by the announcement of more definitive results from a potent European atom-smasher on Wednesday. "Our data strongly point toward the existence of the Higgs boson, but it will take results from the experiments at the Large Hadron Collider in Europe to establish a discovery," said Fermilab spokesman Rob Roser. The results come from 10 years of data from the Tevatron, a powerful atom-smasher that began its collider work in 1985 and closed down last year. "During its life, the Tevatron must have produced thousands of Higgs particles, if they actually exist, and it's up to us to try to find them in the data we have collected," said Luciano Ristori, a physicist at Fermilab and the Italian Istituto Nazionale di Fisica Nucleare (INFN). "We have developed sophisticated simulation and analysis programs to identify Higgs-like patterns. Still, it is easier to look for a friend's face in a sports stadium filled with 100,000 people than to search for a Higgs-like event among trillions of collisions." The Tevatron results show that the Higgs particle, if it exists, has a mass between 115 and 135 gigaelectronvolts (GeV/c2), or about 130 times the mass of the proton. Based on two experiments, known as CDF and DZero, the team found that there is only a one-in-550 chance that the signal is a mere statistical fluke. However, the statistical significance of the signal measures 2.9 sigma, and is not strong enough to meet the five sigma threshold required to say whether or not the particle has been discovered. "We achieved a critical step in the search for the Higgs boson," said Dmitri Denisov, DZero spokesman and physicist at Fermilab. "While 5-sigma significance is required for a discovery, it seems unlikely that the Tevatron collisions mimicked a Higgs signal. Nobody expected the Tevatron to get this far when it was built in the 1980s." A more powerful machine at the European Center for Nuclear Research (CERN) in December 2011 announced "tantalizing hints" that the sought-after particle was hiding inside a narrow range of mass. CERN's Large Hadron Collider -- the world's largest atom-smasher, located along the French-Swiss border -- showed a likely range for the Higgs boson between 115 to 127 gigaelectronvolts. US-based experiments echoed those findings in March 2012, though in a slightly larger range. Now, the scientific community is eagerly anticipating the European results later this week. "It is a real cliffhanger," said DZero spokesman Gregorio Bernardi, physicist at the Laboratory of Nuclear and High Energy Physics at the University of Paris VI & VII. "We are very excited about it.