Tevatron experiments double-team Higgs boson

August 4, 2008
Scientists from the CDF and DZero collaborations at DOE's Fermilab have combined Tevatron data from their two experiments to increase sensitivity for their search for the Higgs boson. While no Higgs boson has been found yet, the results announced today exclude a mass for the Higgs of 170 GeV/c2 with 95 percent probability (see graphs). This is the first time that the Tevatron experiments directly restrict the Higgs mass. Earlier experiments at the Large Electron-Positron Collider at CERN excluded a Higgs boson with a mass of less than 114 GeV/c2 at 95 percent probability. The results show that CDF and DZero are sensitive to potential Higgs signals. The Fermilab experimenters will test more and more of the available mass range for the Higgs as their experiments record more collision data and as they continue to refine their experimental analyses. The expected exclusion limit (red-dotted line with green and yellow bands in lower graph) will move up as the two collaborations collect and analyze more data. Credit: 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. Their results indicate that Fermilab researchers have for the first time excluded, with 95 percent probability, a mass for the Higgs of 170 GeV.

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.

According to the Standard Model of particles and forces, the Higgs mechanism gives mass to elementary particles such as electrons and quarks. Its discovery would answer one of the big questions in physics: What is the origin of mass? Credit: Fermilab
"These results mean that the Tevatron experiments are very much in the game for finding the Higgs," said Pier Oddone, director of Fermilab.

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. In the near future, the Fermilab experimenters expect to test more and more of the available mass range for the Higgs.

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.

The CDF and DZero experiments each comprise some 600 physicists from universities and laboratories from across the nation and around the world. 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.

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.

The Tevatron accelerator and the experiments are operating at peak performance. The Tevatron continues to break records for luminosity, the number of high-energy proton-antiproton collisions it produces. The more luminosity the Tevatron delivers, the more chances experimenters have to see the Higgs. Moreover, by continually improving their experimental techniques, the CDF and DZero physicists have been able to boost their sensitivity to the Higgs and other phenomena by more than the margin afforded by the increased data alone.

"The Fermilab collider program is running at full speed," said Dennis Kovar, director of the Office of High Energy Physics at the U.S. Department of Energy. "In the past year alone, the two experiments have produced 77 Ph.D.s and 100 publications that advance the state of our knowledge across the span of particle physics at the energy frontier."

The new Higgs results are among the approximately 150 results that the two experiments presented at the International Conference on High Energy Physics in Philadelphia held July 29-August 5.

"The discovery of the Higgs boson would answer one of the big questions in physics today," said Joseph Dehmer, director of the Division of Physics for the National Science Foundation. "We have not heard the last from the Tevatron experiments."

Source: Fermi National Accelerator Laboratory

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2.3 / 5 (4) Aug 04, 2008
We are here to report there is nothing here to report.
2.3 / 5 (4) Aug 04, 2008
I think I have had a stroke and lost my ability to read. I can understand how they can rule out lower values but how do they exclude the higher energies without being able to test them yet?
3 / 5 (3) Aug 05, 2008
the higgs particle theory cannot even explain the variety of particles each with a different mass. Maybe the Higgs theory is a lot of hot air.
1 / 5 (1) Aug 05, 2008
What the hell is "It's all 'relative'" supposed to mean in Velanarris' comment? Probably one of those idiots who think Einstein's theory has something to say about ethics. I don't understand it myself, but I understand it, and people, well enough to know most people (including many "scientists") who pretend they have an inkling of understanding about relativity or quantum physics are clueless losers.
4 / 5 (1) Aug 05, 2008
jburchel- I take Velanarris' comment to mean that the value of such knowledge is relevant to some lines of questioning and not others (such as earls' view of the report). Now I feel obligated to point out that "I don't understand it myself, but I understand it..." could also be hard to interpret, though obviously there is a logical thought behind your words (it just takes reading that sentence a few times).

Perhaps we can all just accept that the written word is not a perfect conveyor of thought, and gloss over the occasional misspeak without getting angry?
5 / 5 (1) Aug 05, 2008
@velanarris: The primary mode of human learning is facilitated by the knowledge of what we know something to be because we know what it is NOT. By determining what not to look for we can understand what we should look for. In any event, if the Higgs Theory is wrong, we will only know by looking in every possible place and coming up with, as NeilFarbstein put it (above this comment), nothing but a lot of "hot air".
4 / 5 (1) Aug 05, 2008
@mattytheory- seems like velanarris is one of the ones who agree with you.
not rated yet Aug 05, 2008
Standard science is using an educated guess to figure out the starting reason for where to look and then bounding this location with a bunch of "is nots"
not rated yet Oct 20, 2008
I find it fun that most people think scientists are boring when in fact they are adventurers.

Going where no man has gone before seeking out new ...

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