June 9, 2004

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Contact: Dan Lara, University Relations, (785) 864-8855.

KU researchers part of group unlocking secrets of the 'top quark'

LAWRENCE -- Unlocking the secret of quarks, types of particles that reside inside protons, is a massive undertaking, but that's what 600 scientists from around the world are attempting to do in a laboratory 40 miles west of Chicago.

Four University of Kansas researchers are among a group studying the "top quark," a particle that might help scientists better understand the theories of mass and matter in our world as well as explain the earliest formation stages of the universe, among other atomic mysteries. Some of their research is being published in the June 10 edition of the journal Nature.

"We think the top quark may give us clues to a bunch of things," said Alice Bean, professor of physics and astronomy at KU. "We hope it can help us figure out why some objects around us have more mass than other objects."

The mass of the top quark is an important parameter in the theory of matter, said Philip Baringer, also a professor of physics and astronomy at KU.

"What does it mean for something to have mass?" he asked. "What's holding matter together? What's causing matter to behave the way it does? These are some of the questions the top quark can help us answer."

Quarks are fundamental particles, meaning they can't be broken down into smaller parts.

There are six types, or "flavors," of quarks, Bean said. Inside protons, there are "up" and "down" quarks. Other flavors of quarks have more mass and must be created in high-energy collisions. The top quark is like the up quark, but it has more mass. In fact, the top quark has the most mass of the six flavors.

Scientists started searching for the top quark in the late 1970s, Bean said, and they discovered it in 1995. The article in Nature describes the complex data analysis used to measure the mass of the top quark.

"At the earliest stages of the universe, there was a lot of energy in a small space," Baringer said. "By observing how the top quark behaves in the laboratory, we can better understand what rules and conditions governed the formation of the universe."

Beyond providing more knowledge of the universe's early beginnings, the top quark may help Bean, Baringer and their colleagues locate Higgs particles. Like quarks, Higgs particles, named for physicist Peter Higgs, who postulated their existence in the 1960s, may give all matter their mass. No one has ever seen a Higgs particle, but precise knowledge of the mass of the top quark can help narrow the areas to search for it, Bean said.

"We have to understand how nature works," Bean said. "The research on the top quark is the discovery stage. It will be up to someone else to figure out what to do with the information we find."

Along with Bean and Baringer, Don Coppage, postdoctoral researcher in physics and astronomy, and Christina Hebert, a 2003 doctoral graduate now at the University of Hawaii, are the other KU researchers who are authors on the Nature article.

The KU group has four postdoctoral researchers, two graduate students and three faculty members conducting further study on top quarks.

The actual research is taking place at Fermilab in Batavia, Ill., a suburb of Chicago. The lab contains the world's highest-energy proton-antiproton collider. It's the only lab that allows scientists to study the top quark. The collider makes it possible to "break open" protons. The 600 scientists studying these collisions are called the DZero Collaboration.

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