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Thursday, August 2, 2012

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Dudek, as seen in the National Academies of Science video.
What’s Hot in Nuclear Physics? Ask ODU’s Jozef Dudek

The National Academies of Sciences couldn't have picked a better time to release its new video, "Exploring the Heart of Matter," in which some of the nation's top nuclear physicists – including Jozef Dudek of Old Dominion – explain their research in layman's terms.

Although the video does not directly address the Higgs boson, it was released just a few days before the announcement at CERN's Large Hadron Collider (LHC) in Geneva of the discovery of a particle believed to be the elusive Higgs. That CERN announcement on July 4 was front-page news around the globe because the Higgs particle is thought to be an indicator of how subatomic particles acquire mass.

For nuclear physicists, it was like Christmas in July to have all of this popular attention directed at their arcane endeavors. "Any breakthrough in fundamental science is exciting," said Gail Dodge, a professor of physics at ODU who does experiments at Thomas Jefferson National Accelerator Facility in Newport News. "The fact that I have been asked about the Higgs by non-scientists is especially gratifying. Science should be in the news more often."

Dudek said it is gratifying for someone like himself who has chosen theoretical nuclear physics as a career to make predictions that are borne out by experiments, which is what happened with the Higgs. "The interplay of theoretical prediction and experimental discovery is what's exciting about being a physicist," he added. "The ODU physics department, through its close connection to Jefferson Lab, houses a significant pool of talent in both nuclear theory and experiment."

Physicists at Jefferson Lab, including 11 who are ODU faculty members, are anticipating the completion in 2014 of an energy upgrade that may produce important discoveries of a different vein. The goal of research at U.S. accelerators, as the new video points out, is to explain the fundamental nature of matter, and the 14-minute video devotes several minutes to the role that the Jefferson Lab expects to have in this quest.

In addition to Dudek and researcher David Lawrence from Jefferson Lab, the video's expert commentators are from Brookhaven National Laboratory in New York, the University of Notre Dame, Michigan State, Washington University in St. Louis, and Lockheed Martin Corp.

Dudek, an associate professor of physics at ODU and a nuclear theorist who is affiliated with Jefferson Lab, said he was pleased that the new video has been made available to the public at a time when interest in nuclear and particle physics is high. (The video can be seen by visiting http://sites.nationalacademies.org/BPA/BPA_069589; click on the longer version.)

The young physicist, who was the recipient last year of an Early Career Research Award of $750,000 from the U.S. Department of Energy, conducts research in the field of quantum chromodynamics (QCD). This is the fundamental theory of the dynamics of quarks and gluons, the particles that make up protons and neutrons inside the atomic nucleus. His contribution to this latest video is aimed at putting QCD in terms that a general audience can understand.

A plasma, or soup, of individual quarks and gluons is believed to have been among the basic components that cooled and expanded after the Big Bang and began to form the protons and neutrons of the atoms that make up our universe. The QCD theory posits a mathematical interpretation of the forces that hold quarks and gluons together.

Just as the Higgs theory is one that scientists have been eager to prove through collider experiments, many aspects of the QCD theory await validation, too. It will get increasing scrutiny in coming years after an energy upgrade at Jefferson Lab's electron beam accelerator comes on line. The video notes that the upcoming Gluonic Excitations Experiment (GlueX) at Jefferson Lab is designed to shed light on the dynamics of quarks and gluons.

A major emphasis of Dudek's work – it involves mathematical calculations on supercomputers – is predicting properties of hybrid mesons, which are exotic particles that may exist, according to QCD. These quark-antiquark packages are accompanied by an excitation of the gluon field that binds them.

"A big, unsolved problem is where are they (hybrid mesons)?" Dudek says in the video.

"Now, if we do see what we expect to see when GlueX begins, that really informs us we're doing the right things with the theory," he adds. "If we don't, it's even more interesting because that suggests we've got to rethink our ideas about precisely how QCD is working to bind these quarks and gluons."

Charles Hyde, a professor of physics at ODU who conducts experiments at Jefferson Lab, also does research in the field of QCD. "We, in the Old Dominion University physics department, are excited by the discovery of the Higgs boson at CERN's Large Hadron Collider," he said. "Many of us are passionately working at Jefferson Lab on a related question regarding the origin of the mass of atomic nuclei."

Hyde added in an interview: "The visible matter of the universe is made of ordinary atoms, and the mass of these atoms is dominated by the protons and neutrons in their nuclei. These nuclei – protons and neutrons – are made up of quarks and the Higgs boson particle explains the mass of these quarks. Curiously, however, the quarks contribute only 2 percent of the mass of the protons and neutrons. We seek to understand how the other 98 percent of the mass of ordinary matter is generated, and the nature of the Higgs particle will influence how we examine this question."

The French government awarded Hyde $1 million to work in that country between 2007-2011 on a project that could, in the next few years, literally shed light on the spatial distribution of quarks inside the proton. This, in turn, could help answer questions about the unexplained origin of the other 98 percent of nuclear mass.

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