For particle physicists, the July 4 fireworks took place in Geneva, Switzerland. That’s where UCSB professor Joe Incandela made the historic announcement that the 10-year-old compact muon solenoid (CMS) experiment had revealed a new particle that is strikingly similar to the Higgs boson. It is the most important physics discovery in at least the last quarter century.
The Higgs boson particle was postulated in 1964 by Scottish scientist Peter Higgs among others, but until this year had never been produced. It is so important because it offers an explanation for mass, one of the most fundamental qualities of matter. As Higgs hypothesized, all matter moves through a field — named after him as a Higgs field — and the strength of a particle’s interaction with the field determines its mass, hence the speed at which it accelerates.
One popular analogy that physicists use to describe a Higgs field is “the paparazzi effect.” UCSB physicist David Stuart, who just returned from Switzerland, waved toward the quad outside his UCSB office window and said, “Imagine if President Barack Obama were walking across campus. People would crowd around him and want to talk to him and take his photo. He wouldn’t get too far because his environment would slow him down.” The Higgs field exerts the same sort of effect to different extents on different particles. To follow through on the metaphor, when a random student walks through campus, she would have little interaction with paparazzi, and would therefore move quickly, just as a particle with little mass can move quickly through the Higgs field.
The Higgs field consists of subatomic particles called bosons. As Stuart put it, “The field permeates the universe. If you excite the field, you will produce the particle.”
To excite the field, the CMS experiment took advantage of the Large Hadron Collider (LHC) at CERN, the Organization for Nuclear Research, in the Swiss Alps. The 27-kilometer LHC is the largest collider in the world, and it provided the energy necessary to produce verifiable evidence of a new particle by, in effect, smashing protons against each other. Incandela told The Santa Barbara Independent via email that the LHC was functioning so well after requiring repairs a couple years ago that the CMS group had acquired enough data to announce a Higgs-like particle sooner than he expected.
A second experiment, called ATLAS, also produced the same results which were announced directly after Incandela’s talk. The seminar was timed to coincide with the beginning of the International Conference on High Energy Physics in Melbourne, where Incandela is now. Although the experiments were completed at CERN, the data all go online immediately, and the project is a collaboration — according to the CMS website — between “4,300 particle physicists, engineers, technicians, students, and support staff from 179 universities and institutes in 41 countries.”
A collaboration that large, explained Stuart, is like a small government which functions as a representational democracy. That a UCSB scientist was chosen as the entire “government’s” figurehead is certainly a feather in the cap of the university whose Physics department is ranked among the nation’s top 10 by multiple publications.
UCSB undergraduates, graduate students, postdoctoral fellows, and professors have been contributing to the CMS project throughout, for instance, building silicon radiation detectors and writing software to analyze the experiment’s data. Incandela said that of all the member institutions around the world, he believes that UCSB was a top five contributor.
Michael Witherell, currently UCSB’s vice chancellor for research and a physicist, left UCSB in 1999 for six years to become director of Fermilab in Illinois, home to the largest particle accelerator before the LHC was built. For him, the Higgs discovery was bittersweet. Although elated about the news and the role that UCSB played, he noted that CMS’s location in Europe indicates declining U.S. investment in science research.