Brown scientists were recently key members of a team whose work led to the isolation of a single top quark, the smallest fundamental particle of matter. The research, which involved smashing tiny particles together repeatedly, took place at the Fermi National Accelerator Lab, the location of the Tevatron collider - the world's highest-energy particle collider.
The top quark was "one of the key things that was missing" from the Standard Model of particle physics, said Associate Professor of Physics Meenakshi Narain, who spent years working on the research that ultimately produced the discovery. The isolation of the top quark might be the "last step" on the road to observing the Higgs boson, which is believed to generate mass, she said.
"It was one of those nagging things," Narain said.
The research, which was published in Physical Review Letters earlier this month. was written collaboratively by two teams of scientists that had previously competed to produce the discovery - DZero Experiment and Collider Detector at Fermilab.
David Cutts, professor of physics, was one of the original members of the DZero Experiment. Collaboration is very important because the Tevatron "is a very large piece of equipment - it's very complex," Cutts said.
Narain joined the DZero collaboration as a post-doctoral researcher and was involved in the discovery of the top quark, and the anti-top quark in 1995.
DZero and the CDF have been studying the top quark's properties and production mode ever since, Narain said, adding that this month's discovery is "like a dream come true" after 14 years of experimentation.
"Particle physics is just a very exciting time right now," said Monica Pangilinan GS, a Brown Ph.D. student who is currently on site at Fermilab conducting research. "We're closing in on this window of where the Higgs should be, if it exists."
Pangilinan, who is writing her thesis on the "observation of this rare production mode" of the single top quark, has been closely involved in both the observation and the analysis taking place at the Tevatron, Narain said.
Pangilinan and the rest of the DZero physicists had to analyze billions of collisions in order to find just hundreds that matched the production modes for which they were looking. As part of the analysis, Pangilinan "developed this technique to extract a very small signal from a huge background" Narain said.
The Tevatron fires protons and anti-protons at each other every 396 nanoseconds, but "industry can't support" keeping data about each collision as there is not enough computer space, Narain said.
One of Pangilinan's hardest jobs has been helping to determine which collisions are interesting to the researchers and which to ignore, Narain added.
The analysis would have taken about 1.5 million days if it had run on a single computer, Pangilinan said, adding that the weeks leading up to the publication were "very intense."
Still, neither Narain nor Pangilinan have any intention of stopping now. They are hoping to work with the Large Hadron Collider, located on the Switzerald-France border, which is scheduled to resume operations this fall and one of whose primary purposes will be to isolate the elusive Higgs boson.
"I think I'd like to look for the Higgs," Pangilinan said.
"I personally think there's something beyond the Higgs," Narain, said, adding that "something new has to show up" with energies as high as those at the Large Hardron Collider.
