'God particle may not exist'

Computers recorded the tracks of debris particles

The most sought after object in particle physics, the Higgs boson, may not even exist.

It's more likely than not that there is no Higgs

John Swain, Northeastern University

This is the astonishing conclusion of researchers at the Cern nuclear physics lab near Geneva who have just reviewed five years' worth of data from experiments they thought would confirm the legendary particle's role in the construction of the Universe.

The Higgs, according to the Standard Model of particle physics, is the particle that explains why all others have mass. Its importance is so central to current thinking that some have even dubbed it the "God particle".

But the Cern researchers have told New Scientist magazine that studies in its giant accelerator which should have shown up the presence of the Higgs found absolutely nothing - and this could mean particle physics having to revisit some of its most cherished ideas.

Higgs 'shadows'

If there is no Higgs, science will be left totally unable to explain mass.

Higgs boson

The Higgs is named after British physicist Peter Higgs

He postulated its existence more than 30 years ago to explain how matter has mass

Theory suggests the Higgs gives rise to a field through which all other subatomic particles, such as quarks, gluons, photons and electrons, must pass

As they interact with the field, the particles experience a drag; the more drag, the more massive the particle

Physicists at Cern used what was then the largest atom smasher in the world, the Large Electron Positron (Lep) collider, to search for the Higgs boson.

The theory was that if atoms were hurtled into each other at high enough energies, the Higgs would eventually reveal itself in the sub-atomic rubble.

Just before the Lep was due to be closed down and scrapped, one team declared last year that it was within a hair's-breadth of identifying the Higgs - it had seen tantalizing "shadows" of something which could be the sought after particle.

The Lep got a one-month reprieve for follow-up work and was then closed to make way for a much larger machine. Since then, researchers at Cern have been sifting their data.

Higher energies

Their conclusion is that there was nothing in the data at all to suggest the Higgs is out there - certainly not at energy masses of up to 115 Gigaelectronvolts (GeV), way past the level of 80 GeV where the boson was expected to show itself.

The existence of the Higgs is looking "less and less likely," Steve Reucroft of Northeastern University, Boston, US, a member of the working group, told New Scientist.

"We've eliminated most of the hunting area," confirmed Cern scientist Neil Calder.

And John Swain, also of Northeastern University, said: "It's more likely than not that there is no Higgs."

The collider at Fermilab still hopes to find the Higgs

Not everyone is downcast, however. Frank Wilczek, a particle physics theorist at the Massachusetts Institute of Technology, pointed out that you could take the Lep results as evidence that the Higgs must be sitting at an improbably high energy.

He said he would start to get uncomfortable if the Higgs did not show up by about 130 GeV. "Then I would have a good long think," he said.

And Cern's David Plane is also still hopeful. "It's just at a higher energy than we're sensitive to," he told the magazine.

The Lep is making way for a bigger facility, the Large Hadron Collider, which is due to start crunching particles at even higher energies in 2007.

In the meantime, the baton has been handed to the Fermi National Accelerator Laboratory outside Chicago, US. Researchers there are hopeful they can succeed where Lep failed.