By Eugenie Samuel Reich of Nature magazine
Research groups at the Tevatron, the proton-antiproton collider at Fermilab in Batavia, Illinois, have reached starkly different conclusions about a possible sighting of new particles beyond what is expected under the standard model of particle physics.
In April, researchers on the Collider Detector at Fermilab (CDF) experiment reported tentative evidence that particles not predicted by the standard model had surfaced in collisions that produced a W boson--a particle of the weak nuclear force--and jets of other particles. In May, they released data strengthening the case for the novel particles, and theorists have submitted at least a dozen articles to the online preprint server arXiv trying to explain them.
But today, researchers on the independent D0 experiment, also at Fermilab, announced that their data do not confirm the signal. "The result is not good for the CDF. We are not confirming the signal. We just see nothing," says Dmitri Denisov, spokesman for D0, which released its results online today.
Comparisons needed
Disagreement between the CDF and D0 is rare. Denisov estimates that of the roughly 500 papers produced by the two experiments over the past decade, there have been only two or three significant disagreements. As spokesman for D0, he's naturally more confident in its result, and he suspects that something may be wrong with the way the CDF modeled background events from which its signal was extracted.
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http://www.scientificamerican.com/article.cfm?id=tevatron-teams-clash-over-new-physics