Fermilab collider experiments discover rare single top quark

Scientists of the CDF and DZero collaborations at the Department of Energy's Fermi National Accelerator Laboratory have observed particle collisions that produce single top quarks. The discovery of the single top confirms important parameters of particle physics, including the total number of quarks, and has significance for the ongoing search for the Higgs particle at Fermilab's Tevatron, currently the world's most powerful operating particle accelerator.

Previously, top quarks had only been observed when produced by the strong nuclear force. That interaction leads to the production of pairs of top quarks. The production of single top quarks, which involves the weak nuclear force and is harder to identify experimentally, has now been observed, almost 14 years to the day of the top quark discovery in 1995.

Searching for single-top production makes finding a needle in a haystack look easy. Only one in every 20 billion proton-antiproton collisions produces a single top quark. Even worse, the signal of these rare occurrences is easily mimicked by other "background" processes that occur at much higher rates.

"Observation of the single top quark production is an important milestone for the Tevatron program," said Dr. Dennis Kovar, Associate Director of the Office of Science for High Energy Physics at the U.S. Department of Energy. "Furthermore, the highly sensitive and successful analysis is an important step in the search for the Higgs."

Discovering the single top quark production presents challenges similar to the Higgs boson search in the need to extract an extremely small signal from a very large background. Advanced analysis techniques pioneered for the single top discovery are now in use for the Higgs boson search. In addition, the single top and the Higgs signals have backgrounds in common, and the single top is itself a background for the Higgs particle.

Read more

Reminder

Daylight-saving time began yesterday. While those of us in the Central Standard Time zone turned our clocks ahead one hour, our collabortors throughout the rest of the world may not have. France and Switzerland don't change their clocks until Sunday, March 29. So, for the next few weeks, there will only be a six hour time difference between Fermilab and CERN.

Learn more information on Daylight-saving time in other countries around the globe.

IMSA founder to be honored in D.C.

From Geneva Sun, March 6, 2009

Nobel Laureate Leon Lederman, a one-time director of Fermilab in Batavia, will receive a national award today honoring his long-lasting impact in the science.

Lederman, a high energy physicist and one of the founders of the Illinois Math and Science Academy in Aurora, will receive the 2009 National Space Grant Distinguished Service Award in Washington, D.C.

Lederman is only the sixth person to receive the award, which aims to expand opportunities for Americans to participate in NASA's projects by creating and supporting programs in science, engineering, research and public outreach.

Read more

The latest from the LHC

From symmetrybreaking, March 6, 2009

This week at the LHC, the third sector to be warmed up due to a suspected faulty magnet splice is now at room temperature, and removal of the magnet in question is underway. A prototype for a new anchoring system for another type of LHC magnet is now being tested in the tunnel. If successful, the system would prevent collateral damage to magnets were another large helium leak to occur.

CERN also reports that its Enhanced Quench Protection system for the LHC was favorably reviewed last week by a panel of outside experts. The system, to be installed before the LHC restart later this year, will identify and protect against the type of problem that led to last September’s incident.

Read more