Feature - Friendly but fierce competition for the Higgs |
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The two Tevatron experiments at Fermilab, CDF and D0, have nearly ruled out the hoped-for mass value for the Higgs boson-the particle regarded by some as one of the last big mysteries of the universe. Its discovery could help explain dark matter, dark energy and why particles have mass. Against a tradition of friendly rivalry, the Higgs search provides sufficient motivation for these competitors to combine their analyses. Teams from each experiment run simulations on the Open Science Grid and compare their models to actual data. The process of combining results is a significant analysis in itself. The scientists must account for the unique uncertainties in each component of their different detectors. "You don't want one group to say they've discovered the Higgs and, using the same data, the other group to say it's background," says CDF physicist Tom Junk. "That would be embarrassing." Sharing hard-earned data requires trust. "We spend almost the entire year dug down in our trenches, staring across at each other," says D0's Wade Fisher. "Now we're giving them our data, saying, 'Here, open up the hood and poke around the engine a bit'." Through their combined efforts, the joint CDF/D0 collaboration has amassed enough data to state with 90% certainty-and likely 95% by year's end-that the Higgs does not have a mass of 160 GeV/c2. That may seem a funny way to state a result, but it gets to the heart of the matter. The Large Hadron Collider, CERN's massive new accelerator, will be seven times more powerful than the Tevatron. Its Higgs "sweet spot," however, sits at 160 GeV/c2. If the Higgs isn't there, the CERN experiments will have to work harder to find it. |
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Meanwhile, the Tevatron physicists will continue to accumulate and process data. "Two years ago, we didn't appear to have much chance of finding the Higgs," said CDF's Mark Kruse. "The use of Open Science Grid resources has enabled us to run more simulated samples, and larger ones, which in turn has enabled us to exploit the data in increasingly sophisticated ways. I think people are starting to believe we have a realistic shot at the Higgs." |