Exciting ... Mark Scarcella works on particle collisions from the Hadron Collider. Credit:Ben Rushton But they may have discovered the exact opposite, that it is not there, says Geoffrey Taylor, director of the ARC Centre of Excellence for Particle Physics at the Tera-Scale. ''Whatever happens, the importance of this announcement cannot be understated,'' he said. Finding the Higgs boson would fill in the last major missing piece in the Standard Model that describes how particles and forces interact, and show that scientists are on the right track in their quest to understand the cosmos. The Higgs boson is central to this theory because it is thought to give all other particles their mass - just as hangers-on at a party can weigh down a celebrity moving through a crowd. But ruling out its existence would be just as important as finding it, says Mark Scarcella, a physics PhD student at the University of Sydney. ''It would still tell us about how the universe works, and force us to come up with new models to explain what is happening,'' he said.

Even though it is tiny, searching for the Higgs boson requires enormous equipment. In the Large Hadron Collider, beams of protons are accelerated to almost the speed of light around a 27-kilometre-long loop before being smashed into each other. Australian researchers helped design the 7000-tonne ATLAS detector that, along with the CMS detector, analyses the myriad of particles produced in the 40 million or so collisions a second. The mysterious boson would be so short-lived it could be spotted only from the excesses of lighter particles it decays into. Finding it has been likened to detecting zebra tracks under those from a stampede of horses. ''It's very hard to see,'' Scarcella says. In December last year, the ATLAS team and their friendly rivals at CMS both announced they had captured a tantalising glimpse of the particle, after analysing 3 trillion collisions. The signals from both detectors suggested the Higgs particle was where it should be, at a mass of 124-126 gigaelectronvolts. This is equivalent to about 130 times the mass of a proton. Researchers declare a discovery only when a result has a statistical significance of five sigma, which means a less than one-in-a-million chance of it being just a fluke. The results were only 2.5 sigma for ATLAS and 1.9 sigma for CMS.

''It was very exciting. But not conclusive,'' says Scarcella, who mainly works on detecting different particles, called taus, with ATLAS. In April the energy of the collisions was increased from a record seven to a record eight teraelectronvolts. And that is why there is such great anticipation among physicists. ''We have more than twice the amount of data, we have a much better understanding of analysis techniques and the way the machine works. So we can be much more confident in the results we get,'' Scarcella says. The 24-year-old spent three months at the collider in late 2010, training to work in the control room, and hopes to help run the giant instrument next time he visits. Loading

Before the collider started up in 2008, scientists had to hose down claims it would destroy the world by creating a giant black hole. Scientists also do not like the term God particle. ''We kind of shake our heads and roll our eyes when we hear it,'' Scarcella says. But the young physicist is pleased the Higgs boson has captured the public's imagination, with rumours of its discovery popular on Twitter ''It's sparked a lot of interest.''