Higgs boson still eludes capture – but now we know where it isn't

Scientists are a step closer to discovering an elusive particle that is thought to give mass to the basic building blocks of nature.

Physicists hunting the Higgs boson at the Tevatron particle collider near Chicago said their latest results will help researchers close in on the long-sought prize.

The Tevatron, which is the main rival to the Large Hadron Collider (LHC) at Cern, near Geneva, has ruled out a quarter of the energy range where the Higgs particle is expected to be lurking, scientists told the International Conference on High Energy Physics in Paris today.

The announcement follows weeks of speculation that physicists had seen glimpses of the Higgs particle at the US collider. The rumours were denied by staff at Fermilab, where the Tevatron is based.

"We've updated and upgraded all of our analyses and right now, we just need the Tevatron to keep running the way it is," said Robert Roser, co-spokesman for a collaboration of 550 physicists who work on the Tevatron's CDF detector.

The Tevatron collides beams of protons with beams of antiprotons (their antimatter counterparts) at close to the speed of light inside a four-mile underground ring. The machine is less powerful than the LHC, but has been running for longer and has a head start in the hunt for the Higgs particle.

Previous experiments suggest the Higgs particle has a mass somewhere between 114 and 185 GeV (gigaelectronvolts), where one GeV is roughly equivalent to the mass of a proton, a subatomic particle found in atomic nuclei.

The latest results from the Tevatron, which combine the efforts to find the Higgs particle from its two detectors, CDF and DZero, rule out the possibility that its mass is between 158 and 175 GeV.

"Our goal first of all is to find the particle if we can, not to exclude where it might be, but we'll take what we can get," said Roser. ...

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