Joint CDF, DZero effort lands Fermilab in Higgs territory

Aug 04, 2008

Wintertime at Fermilab.

Scientists from the CDF and DZero collaborations at the U.S. Department of Energy's Fermilab have combined Tevatron data from the two experiments to advance the quest for the long-sought Higgs boson. They have presented their results on August 3rd at the International Conference on High Energy Physics in Philadelphia indicating that they have for the first time excluded, with 95 percent probability, a mass for the Higgs of 170 GeV (about 170 proton masses). This value lies near the middle of the possible mass range for the particle established by earlier experiments. This result not only restricts the possible masses where the Higgs might lie, but it also demonstrates that the Tevatron experiments are sensitive to potential Higgs signals.

The Standard Model of Particles and Forces--the theoretical framework for particle physics--predicts the existence of a particle, the Higgs boson, that interacts with other particles of matter to give them mass. The mechanism by which particles acquire different mass values is unknown, and finding evidence for the existence of the Higgs boson would address this fundamental mystery of nature.

In this plot the solid black line is above the "95% CL" blue line in a small mass range around 170 Gev/c2. This indicates that the existence of a Higgs boson in this mass range is excluded with a 95% probability.

Combining results from the two collider experiments effectively doubles the data available for analysis by experimenters and allows each experimental group to cross check and confirm the other's results. "These results mean that the Tevatron experiments are very much in the game for finding the Higgs," said Pier Oddone, director of Fermilab. In the near future, the Fermilab experimenters expect to test more and more of the available mass range for the Higgs.

The CDF and DZero experiments each comprise some 600 physicists from universities and laboratories from around the world. CEA Irfu/SPP and CNRS IN2P3 teams play an important role in search for Higgs boson in D0 experiment and then in result combination. Currently, Fermilab’s plans call for the Tevatron experiments to continue operating through 2010. In that time, both groups expect to double their analysis data sets, improving their chances to observe the Higgs.

The D0 control room

Scientists expect operations to begin at the Large Hadron Collider at CERN, in Europe, sometime later this year. Observation of the Higgs is also a key goal for LHC experiments. If the Higgs is “light”, search at LHC and Tevatron will be complementary, because observable production and decay modes are quite different at these two facilities.

More inforamation : Ursula BASSLER, Marc BESANÇON CEA-Saclay, Irfu/SPP

#2475 - Last update : 08/04 2008

Institute of research into the fundamental laws of the Universe

Fundamental Research Division