Kelsey Bilsback is pinching herself. Rarely do the arcana of particle physics dominate global headlines. But physics major Bilsback, an intern at the CERN Laboratory in Geneva, finds herself among physicists from around the world flying high after CERN’s confirmation July 4 of evidence of a new subatomic particle that could dramatically advance our understanding of the universe.
With its faculty and graduate presence at CERN, BU has played a notable role in the massive collaborative effort that after half a century of experiments and analysis of unprecedented amounts of data has found a particle that could prove to be that subatomic Holy Grail known as the Higgs boson. The elusive particle could provide the last ingredient in science’s working model of the universe. CERN posted the announcement under the headline “Higgs within Reach.”
“I feel pretty excited and very, very lucky,” says Bilsback (CAS’13), who along with most of the other BU students opted to watch a live feed of the 9 a.m. announcement rather than queue up before dawn to hear it in person. Bilsback is fortunate in many respects—BU is the only university to offer an academic-year undergraduate internship program at the Large Hadron Collider (LHC), the firmament of particle physics research. Some people waited all night to get into the CERN auditorium to meet a lineup of particle physics luminaries, among them Peter Higgs, the University of Edinburgh professor emeritus who proposed the existence of the Higgs boson in the 1960s.
Kevin Black, a College of Arts & Sciences assistant professor of physics, was there too, and he describes an atmosphere of “elation and jubilation.” Black has been working on the LHC since 2005, three years before it was officially completed. “One thing I should point out is that in ‘big science’ there can often be 10, 20, or even 30 years between the conception, design, and execution of a successful experiment, many of which end in disappointment,” Black says. “When you get a big result—those are typically far and few between.” There are people who have searched for the Higgs for their entire professional careers. Black reports that Higgs himself, now 83, was in tears when he saw the data.
Currently being hailed, deciphered, analyzed, and demystified in scientific and lay press around the world, last Wednesday’s news might best be summed up as the result of supercomputer number-crunching on an epic scale. The data in the Higgs boson quest have been long in coming and will continue to flow, but according to CERN, “the 2012 LHC run schedule was designed to deliver the maximum possible quantity of data to the experiments before the ICHEP conference, and with more data delivered between April and June 2012 than in the whole 2011 run, the strategy has been a success.” And the confirmation level of the data consistent with Higgs boson is 5 sigma, which in the particle physics world means that the chance that the information is wrong is only one in 3.5 million. The massive LHC is the flagship project of CERN (Conseil Européen pour la Recherche Nucléaire), now officially called the European Organization for Nuclear Research, a joint venture recognized by the scientific community as the world’s largest particle physics center. The LHC, a 16-mile underground vacuum tube lined with 4,000 of the world’s most powerful superconducting magnets straddling the Franco-Swiss border, can accelerate two beams of protons so they collide at close to the speed of light, creating explosions of particles similar to the immediate aftermath of the Big Bang. Researchers analyze the debris of the fleeting particles as they decay.
Exceeding its design specifications, the LHC computing grid has analyzed an unprecedented torrent of data to pick out Higgs-like events from the millions of collisions occurring every second. In fact, in the two weeks preceding last week’s announcement, researchers analyzed about 800 trillion proton-proton collisions that had occurred over the last two years.
Lawrence R. Sulak, David M. Myers Distinguished Professor of Physics and director of BU’s internship program, who is on sabbatical at CERN, was among the 3,000 signatories to the July 4 research update that shook the world. “If the accelerator performs as anticipated, by the end of this run in February 2013, we hope to verify whether the new particle is the boson of the Standard theory,” says Sulak.
The Standard theory Sulak refers to is the Standard Model of particle physics, for which Sheldon Glashow, Arthur G. B. Metcalf Professor of Mathematics and Science, shared the 1979 Nobel Prize in Physics. Glashow’s theory has been extended by colleagues Andrew Cohen and Kenneth Lane, CAS physics professors, and Martin Schmaltz, an associate professor. The Standard Model of particle physics, sometimes called “the theory of everything,” concerns the interactions that mediate the behavior of subatomic particles. Long-standing questions revolve around shortcomings in the Standard Model, which lists the simplest particles known to exist (such as electrons, muons, and quarks) and describes how three fundamental forces—electromagnetism, the strong force that holds together the nuclei of atoms, and the weak force that underlies radioactive decay—act on them. But the Standard Model neglects gravity, and it offers no explanation for “dark matter,” a phenomenon indicating that most of the universe’s mass is invisible because it doesn’t emit light. The existence of the Higgs boson and the related Higgs field would provide the missing piece of the model and solve one of physics’ persistent mysteries—why some subatomic particles, like the quarks that make up protons and neutrons, have mass and others, such as electrons, are super-light.
Tulika Bose, a CAS assistant professor of physics and a 2012 Sloan Fellow, is also working at CERN and called the July 4 developments groundbreaking. If the particle proves to be something more exotic than the Higgs boson, that would be “particularly exciting,” says Bose, “since it would revolutionize our current understanding of particle physics.” It may also help answer some of the fundamental questions facing particle physics today, she says, and in any case, the LHC results will inspire physicists to arrive at “a more complete theory that includes everything.”
The idea of sending undergraduates to be part of this sweeping effort was born five years ago, when, “with the nexus of particle physics having moved from the United States to Geneva,” Sulak says, “we realized that BU students should be trained at CERN, where all the action is.” Funded by BU and the U.S. Department of Energy, the eight-month stints (Bilsback and several others have opted to stay on at CERN through the summer) constitute the only such program in the world, according to Sulak. In the program’s three years of operation, 23 BU undergraduates have participated, according to Sulak.
Bilsback, who plans to earn a PhD in physics, is the only BU intern working on CERN’s ATLAS detector, the LHC experiment providing most of the data for Higgs. And with the LHC being the Mecca of particle physics, great minds are everywhere. “It was a bit intimidating at first; everyone is a doctoral or postdoc student,” says Bilsback, who like fellow CERN interns has lunched with international Nobel laureates. “But everyone has been so welcoming and helpful.”
Back at BU, Glashow explains that in the world of particle physics, each new discovery opens the door to many others. The Higgs boson is “the last of the particles predicted by the theory I shared the Nobel Prize for,” says Glashow, “but everyone agrees there have to be other particles, and other structures as well.” As for headlines touting discovery of “the God particle,” Glashow’s distaste is pronounced. “That’s not a term we use,” he says. The catchy term is traced to the title publishers gave to a 1993 book about the Higgs boson by Leon Lederman, The God Particle: If the Universe Is the Answer, What Is the Question? Lederman was “not too happy” about the title, Glashow says. “Nobody likes to use that term. It has nothing to do with God. It’s just a very important particle.”