Indeed, Tommaso Dorigo, a member of the CMS collaboration at CERN in Geneva, which is also concerned with the analysis of symmetry in particle decays, cautions that the anomaly might not be so large if the uncertainty in the predicted asymmetry has in fact been underestimated. One potential cause of such an underestimation could be the modelling of how quarks and gluons are distributed within the colliding protons and antiprotons. So-called parton distribution functions, he points out, are measured in other experiments and then extrapolated to the energies at which the Tevatron operates and it is possible, he says, that this extrapolation produces a larger uncertainty than estimated. "The predicted asymmetry is just like a soup," he adds, likening the soup's recipe to the Standard Model. "There are many ingredients in the soup, and if the soup tastes bad, this may mean that one ingredient was not fresh; it does not necessarily mean that the recipe is wrong."

Establishing whether or not the latest result is watertight will require collecting more data at the Tevatron, says Roser. As he points out, the Tevatron is ideally suited to studying this asymmetry because the proton/anti-proton collisions automatically lead to pairs of top quarks and anti-top quarks. Producing anti-top quarks at the LHC, in contrast, requires collecting huge amounts of data because the accelerator's collision energy must be just right to produce an anti-top quark out of the vacuum. Roser adds that he is "disappointed but not surprised" that the Tevatron has not been granted a hoped-for extension beyond September, but expects the US collider to "still dominate the physics landscape for the next year to 18 months".

REF:http://physicsworld.com/cws/article/news/44784