Part of a U.S. Department of Energy initiative, research will advance theoretical frameworks in five areas, furthering accurate predictions of nuclear interactions and properties of nuclear matter

Temple University’s Department of Physics is part of a national wide-ranging collaboration focusing on solving challenging problems central to advancing knowledge in nuclear physics.

Bringing together leading nuclear theorists, the U.S. Department of Energy announced $11.24 million for five collaborations focusing on theoretical topics in nuclear physics. Temple will lead the Quark-Gluon Tomography (QGT) Collaboration. The principal investigator (PI) on the project is Martha Constantinou, associate professor of physics, who also holds one of the the College of Science and Technology’s Selma Lee Bloch Brown Professorships. The co-PI is Andreas Metz, professor of physics.

Using tomography—a process of forming images of the interior of an object from measurements made from high-energy scattering processes —the QGT Collaboration will develop the theoretical framework for exploring the 3-dimensional internal structure of visible matter’s core: the nucleons and nuclei. With such a theoretical framework, the collaboration will be able to make state-of-the-art predictions on the properties of fundamental particles.

“Fundamental particles like the nucleon are made out of quarks and gluons, which govern their properties,” explains Constantinou. “Understanding how quarks and gluons build the visible universe is one of the grand challenges of modern science.”

With a three-dimensional map of the motion and spatial position of quarks and gluons within the nucleons, Constantinou says researchers can begin to address many essential—and still unanswered—questions: How do the spin and orbital angular momentum of quarks and gluons within the nucleon combine to make up its total spin? What is the origin of the mass of the nucleon and other hadrons? Where are the quarks and gluons located within the nucleon? How does the quark-gluon structure of the nucleon change when it is bound in the nucleus?

Joshua Miller, a physics graduate student, is using supercomputers based in both the U.S. and Europe to study the quark component of the proton’s 3-D structure. “The framework that will be developed within the QGT collaboration will enable scientists to, for instance, make predictions for the upcoming facilities like the Electron-Ion Collider (EIC),” says Miller. “The analysis of EIC measurements would have guidance from theoretical data on how to interpret experimental data. This is important as it allows the scientific community to be well-prepared for when EIC is operational.”

Several Temple faculty members have been involved in various aspects of the EIC, such as the site selection, detector requirements and research priorities for the EIC, which will be built at Brookhaven National Laboratory and scheduled to be operational by mid next decade, including Constantinou, Metz and former physics chair Professor Bernd Surrow.

The QGT Collaboration, which will receive more than $2.5 million in DOE funding over three years, is a consortium of 12 universities and three national laboratories. Part of the funding is allocated for a bridge faculty position in nuclear theory at Temple. “Having a diverse group of scientists with different expertise is imperative to the success of the scientific goals of the QGT Collaboration,” says Constantinou. “The participation of the labs is particularly critical, as they host leading experimental worldwide. Collaborating with national labs will also benefit our graduate students and postdoctoral fellows, as it can offer mentorship, networking, and research opportunities at DOE laboratories.

Two other physics graduate students are currently part of the initiative, with a plan to bring in additional young Temple researchers. Chris Cocuzza is investigating the spin structure of the nucleon in terms of quarks and gluons, and Joey Delmar is studying the gluon structure of fundamental particles like the proton, pion and kaon.