July 5, 2012 — Scientists working at the Large Hadron Collider in Europe announced Wednesday that they have found the strongest evidence to date of the likely existence of the Higgs particle.

The Higgs is sort of a holy grail for physicists – a particle that is believed to give mass to every other particle in existence and may be the underlying basis of matter, essential to the formation of the universe. Everything is held together because of it. Physicists have been searching for experimental evidence of the particle for nearly 50 years, ever since it was theorized to exist by renowned British physicist Peter Higgs.

Listen to the UVA Today Radio Show report on this story by Fariss Samarrai:

"We've had an observation that very likely is the Higgs," said University of Virginia physicist Brad Cox in the College of Arts & Sciences, who has been involved with the Higgs search at the Large Hadron Collider. "With more experimentation and analysis, we are within reach, possibly by the end of the year, of confirming that the particle that we have seen is the Higgs. If so, this will be one of the major findings in physics in half a century."

The Higgs is the last remaining semi-unverified ingredient in the Standard Model of Physics, which physicists use to describe the basic building blocks of matter and their interactions.

Cox is a member of a four-person scientific review committee in the Compact Muon Solenoid experiment at the Large Hadron Collider that made the decision to "green light" the announcement that the collider had produced a new particle that may be the Higgs.

"Long hours were spent over six weeks poring through the data, deciding whether or not we were seeing a strong enough signal to announce a finding," he said. "The evidence is that we have a clear observation of a particle that most probably is the Higgs. We will, of course, continue to conduct experiments and analyze data in the coming months before we can call it a discovery of the Higgs. The main issue is that we must do tests on the particle to see that it has all the expected characteristics of the Higgs."

In the meantime, the particle has a less than 80,000 to 1 chance to be an aberrant background signal.

"According to these odds, we are observing a new particle and it has many of the expected characteristics of the Higgs," Cox said. "It's pretty definitive. But we want to be even more sure than that. By the end of this year we'll have twice the data we have now. We'll likely know then for sure. If so, it will be one of the more important fundamental discoveries of all time, like the discovery of the photon."

The Large Hadron Collider is located on the Swiss/French border. It was activated in November 2009 after nearly two decades of planning and construction. High-energy beams of protons are circulated at nearly the speed of light around a 17-mile circular accelerator, producing powerful collisions that shatter the protons into their component particles. The Higgs is believed to be hidden among the more common, widely observed particles. The experiments replicate conditions of the early universe.

Cox has spent many years as a member of a huge international team preparing for experimentation using the $10 billion collider. He and other members of U.Va.'s High Energy Physics Group also have built components for detectors on the collider, which has amassed data from billions of particle collisions.

It is one of the world's most ambitious scientific undertakings and the largest scientific instrument ever.

Early Wednesday morning, Cox and other members of the U.Va. group plan to watch a video feed of the announcement and press conference from their conference room on Observatory Hill.

"This is the kind of scientific event that happens only every two or three decades," Cox said. "It is very gratifying to be part of it, to know that some of the equipment we designed and built in our labs is at work on the Large Hadron Collider and giving us the data needed to answer some of the most important questions in science.

"It's like being on a championship team; getting to wear the ring, knowing your efforts paid off – we think."

– by Fariss Samarrai