Rutgers Physicists Contribute to Worldwide Search for the Higgs Boson

CERN

Rutgers particle physicists got an early start to their July 4 holiday by watching a 3 a.m. webcast from Switzerland that unveiled a discovery they contributed to: a subatomic particle consistent with the long-sought Higgs boson.

Sometimes dubbed the “God particle” for its role in explaining the physical universe, the Higgs boson is said to confer mass upon all the matter in the universe. Scottish physicist Peter Higgs and others postulated it almost 50 years ago. But of all the pieces that make up the so-called “standard model” of particle physics, this particle has been most elusive. Scientists have been using powerful accelerators to find it by smashing atomic particles together at close to the speed of light and examining the debris that spews out of these high-energy collisions.

The carefully worded announcement, in which scientists declare they’ve seen a new particle but cautiously label their discovery as merely “consistent with” the Higgs boson, might leave laypeople scratching their heads. But physicists are excited about the news.

“It’s a new particle, but the fun has really just begun,” said Yuri Gershtein, associate professor in the Department of Physics and Astronomy in the School of Arts and Sciences. “Everything we observed is consistent with it being the standard model Higgs boson, but we need more data to absolutely figure this thing out.”

Gershtein attended the webcast at the Melbourne Convention and Exhibition Centre in Australia, where scientists packed into a large meeting room on the eve of a biennial high-energy physics conference.

“This is a reflection of how global our science is,” he said. “Many people are involved in studies like these.”

CERN

Gershtein explained that the new particle could actually be other types of Higgs particles described by extensions to the standard model of particle physics, most notably one called supersymmetry. Two Rutgers professors, Eva Halkiadakis and John Paul Chou, are leading a research team searching for evidence of theories beyond the standard model.

The search in earnest for the Higgs boson began more than a decade ago at Fermilab, where Rutgers physicists joined a worldwide team to study proton-antiproton collisions in a four-mile ring buried under the Illinois prairie west of Chicago. They stepped up their search in 2008 at CERN, the European Organization for Nuclear Research, examining proton-proton collisions in the more powerful 17-mile Large Hadron Collider (LHC) beneath the mountains of France and Switzerland near Geneva.

Rutgers is involved in one of the two major particle collision detectors at the LHC, known as the Compact Muon Solenoid experiment, or CMS.

“Since 1995, we have made major contributions to constructing and operating the detector, as well as analyzing the data that hold clues of the Higgs,” said Amit Lath, associate professor in the Department of Physics and Astronomy. Rutgers contributions include electronic chips for a 60 megapixel digital camera that captures images of particles scattering from the collisions, and a device called a calorimeter that measures the energy of photons produced in those collisions. For the Higgs search, Rutgers developed analysis routines that looked for evidence of the Higgs particle decaying to two photons.

Scott Thomas

“While physicists don’t actually see the short-lived Higgs boson itself, we can see its footprints – the evidence of its decay,” said Lath. He explained that a Higgs decay to photons is quite rare, but when it happens, it’s much easier to discern amid the “noise” of collision debris than the more typical decay route to particles known as W and Z bosons.

Lath and several colleagues attended the Geneva webcast at a “pajama party” held at the Institute for Advanced Study in Princeton. It was one of many post-midnight gatherings at universities around the country, including one in Washington state at a bar – perhaps the only time a physics conference displaced a sporting event on a bar's TV screens.

He agrees that the discovery paves the way for new studies. Rutgers scientists are particularly interested in delving into one of the ways that Higgs bosons are produced at the moment when two protons collide. Their study of “vector boson fusion” will help determine if the new particle is a standard model Higgs or one of its variants.

Rutgers participants in the Higgs search and other studies at the LHC include faculty members Lath, Gershtein, Halkiadakis, Chou, Sunil Somalwar, Steve Schnetzer and Scott Thomas. They also include senior scientist Robert Stone and another dozen or so postdoctoral researchers, graduate students and undergraduates.

CERN announcement of search for Higgs boson

Fermilab announcement of search for Higgs boson

Rutgers Research Highlights, 2010: Scientists Cheer Restart of "World's Largest Physics Experiment." in Switzerland