Physicists at Texas A&M University are celebrating a flagship result out of the Collider Detector at Fermilab (CDF) that could have big implications in explaining dark matter.
After sifting through 10 years of data gleaned from roughly 350 trillion proton-antiproton collisions by Fermilab’s powerful atom-smashing Tevatron, the CDF collaboration — which features about a dozen Texas A&M physicists — has detected a slight excess in the data analyzed as part of their painstaking search for rare particle decays.
This anomaly, detailed in a paper submitted Wednesday (July 13) on http://arXiv.org and feted today (July 15) in a 2 p.m. seminar presentation at Fermilab as its “Result of the Week,” may represent the first hints of such rare decays — important because they can shed light on subatomic processes impossible to be directly observed — as well as potential vindication of a novel idea conceived nearly a decade ago at Texas A&M.
In 2002 Texas A&M high-energy physics experts Teruki Kamon (an experimentalist), Richard Arnowitt and Bhaskar Dutta (both theorists) first proposed a new and powerful method to test for special connections between particle physics (the smallest things in the universe) and cosmology (the entire universe itself), noting the huge potential of the Tevatron to discover a new theory, supersymmetry, that could be consistent with cosmology.
The Texas A&M trio, pioneers in combining theory and experiment at a single university, published their findings in the international journal “Physics Letters B,” zeroing in on rare particle decays — which have never been observed to date — as their preferred technique and suggesting that the first evidence for supersymmetry might be observed through the CDF experiment.
After initially finding nothing of significance in three previous analyses reported in 2004, 2005 and 2008, Kamon says persistence — not to mention 20 times the data — has paid off in what appears to be a slight deviation in the decay rate as predicted by standard model. While the jury’s definitely still out, he says it’s a strong indication of the possible existence of something new, potentially a new elementary particle or, at the very least, novel interactions between those known to exist in the universe.
“This is a remarkable and unusual synergy of experiment and theory, done at very few places around the country,” Kamon says. “If our ideas are correct, then the dark matter that fills the universe could be a type of supersymmetric particle which can be detected directly. If the type of supersymmetry we are looking for is correct, our novel method could be the best way to discover it at a collider — the only way in which it could be discovered.”
Kamon notes the standard model predicts that the rate of one specific particle found in the universe known as a bottom-strange quark meson (Bs) decaying into two muons (the rough equivalent of heavy electrons) is extremely small — comparable to the odds of a specific person being selected at random from the entire population of the United States — and would require quadrillions of collisions to be seen. He says the new result provides tantalizing hope ― given that it is based on more collisions and data obtained with increased sensitivity, thanks to a sophisticated neural net technique that separates signal noise from background noise ― but also cautions that it’s not conclusive, because the number of observed decays indicated is not yet significant or consistent enough to warrant anything beyond further study. However, he says it does begin to constrain the predictions from supersymmetry and other theories, thus narrowing the region of searches for new physics.
“This is a very nice example of the synergy between Texas A&M theorists and experimentalists that helped lead to one of the most significant results in modern searches for supersymmetry,” Kamon adds. “Although supersymmetry may not have been definitively discovered, these results allow for a much better understanding of what kind of supersymmetry can still be realized in nature.”
To learn more about the CDF collaboration and Texas A&M’s role in it as well as view past papers and related research, visit the Texas A&M Collider Physics website at http://collider.physics.tamu.edu.
For more information on high-energy physics at Texas A&M, go to http://physics.tamu.edu/research/list-high_energy.html.
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