Collisions hint that quarks might not be indivisible

When two groups of particle physicists at the Fermi National Accelerator Laboratory announced last March that they found the top quark, they put the capstone on the current theory of the fundamental structure of matter, called the Standard Model. Now, just short of a year later, Science has learned that one of those groups has evidence that could challenge the model. During a yearlong run on Fermilab's Tevatron particle accelerator, the CDF collaboration-for Collider Detector at Fermilab-observed an unexpectedly large number of open-quotes hardclose quotes or violent, collisions between quarks, which the Standard Model identifies as a fundamental building block of matter. open-quotes This is just the sort of effect you would see,close quotes says CDF co-spokesperson William Carithers, open-quotes if quarks were not fundamental particles but had some sort of internal structure.close quotes