God particle glimpsed?

Nothing makes my ears prick up more than a rumour that the Higgs boson has been found. For years physicists have been searching for this fleeting speck of matter using the most powerful colliders they have to hand at CERN and Fermilab. The Higgs boson tops the list of physicists? most-wanted discoveries - some have even dubbed it the God particle.

So when I stumbled across a blog by Tommaso Dorigosuggesting that his experiment might just have found the Higgs, I avidly read on.

Dorigo is in the know. He is a particle physicist at the University of Padova in Italy and works on the CDF experiment (pictured), one of two vast detectors built to analyse collisions between protons and antiprotons at Fermilab?s Tevatron accelerator.

The rumour that CDF has seen the Higgs is already spreading.

So why the fuss? Our best theory of matter and the forces that glue it together predicts that the Higgs is what gives other particles their mass.

You?re made up of atoms - some of us more than others. And atoms get their mass from the protons, neutrons and electrons inside. But start asking where electrons and the quarks that reside inside protons and neutrons get their mass from and you?ve hit one of the biggest unknowns in physics.

In the 1960s, theorist Peter Higgs at the University of Edinburgh worked out a mechanism to do it, involving a particle later named after him. It?s our best stab at an answer, so finding the Higgs is a really big deal.

In the CDF experiment, the energy created when protons and antiprotons smash together transforms itself via the equation E=mc² into massive particles, including (physicists hope) the Higgs. In fact, recent results from CDF showed in a roundabout way that the Higgs should probably weigh no more than about 153 GeV, or 160 times heavier than a proton and well within reach of the Tevatron.

According to theory, the Higgs boson lives for less than the blink of an eye before decaying into other particles. Among the easiest to spot amid all the detritus in the detector should be the decay to two heavy electron-like particles called taus. From the momentum and energy of the tau pairs, the CDF team can work out the mass of the mother particle.

CDF found a small bump in their mass plot near 160 GeV ? on the fringes of the allowed range. Dorigo is careful to point out that the statistical significance of the result is not yet strong enough to claim a discovery. The measurement lies only two standard deviations outside the theory.

?We?d need 3 standard deviations before we claimed we?d seen a hint of the Higgs,? says Mark Lancaster, a particle physicist at University College London and a CDF team member, ?and we?d need 5 standard deviations before we said anything officially.?

My guess is that when the experiment collects more data, this enigmatic signal will disappear. Which would be a shame. I?d love the Tevatron to find the Higgs before the next big atom smasher, the Large Hadron Collider (LHC) at CERN, gets into its stride.

Though the LHC is due to turn on later this year, it will take months or years to get enough collisions to claim a discovery.

So there still a chance that the Tevatron could pip the LHC to one of the biggest prizes in physics. It?s just what particle physics, especially in the US, needs to maintain the public?s interest and government funding.

Dorigo?s blog raises another interesting point. Particle physics is big science and its collaborations are getting bigger. More than 400 physicists are members of the CDF team. At the LHC, the teams are 1800 strong. With so many team members and the ever fattening blogosphere, how will the teams stop news of their results from leaking out before they are ready to publish? And should they even try to stop it?

Valerie Jamieson, features editor (Image of Central Detector at CDF: Fermilab)