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Dr. Michael Strickland's group at �鶹��ѡ will participate in a new Topical Theory Collaboration funded by DOE’s Office of Nuclear Physics to explore the behavior of heavy flavor particles. These particles are made of quarks of the “charm” and “bottom” varieties, which are heavier and rarer than the “up” and “down” quarks that make up the protons and neutrons of ordinary atomic nuclei. By understanding how these exotic particles form, evolve, and interact with the medium created during powerful particle collisions, scientists will gain a deeper understanding of a unique form of matter known as a  (QGP) that filled the early universe.

These experiments take place at the  (RHIC) at Brookhaven National Lab and the  (LHC) at Europe’s CERN laboratory. Scientists accelerate and collide nuclei of heavy atoms at energies high enough to liberate the quarks and gluons that hold ordinary matter together. These collisions create a soup of quarks and gluons that is very similar to the matter that existed just after the Big Bang, some 14 billion years ago.

A powerful theory, known as quantum chromodynamics (QCD), describes very accurately how the plasma’s quarks and gluons interact. But understanding how those fundamental interactions lead to the complex characteristics of the plasma — a trillion-degree, dense medium that flows like a fluid with little viscosity — remains a great challenge in modern research.

The Heavy-Flavor Theory (HEFTY) for QCD Matter Topical Theory Collaboration seeks to close that gap in understanding by developing a rigorous and comprehensive theoretical framework for describing how heavy-flavor particles interact with the QGP.  The HEFTY Topical Theory collaboration will develop a theoretical framework for describing the behavior of heavy quarks at various stages in the evolution of hot nuclear matter to gain a deeper understanding of the quark-gluon plasma that filled the early universe.

“With a heavy-flavor framework in place, experiments tracking these particles can be used to precisely probe the plasma’s properties,” said Peter Petreczky, a theorist at Brookhaven Lab, who will serve as co-spokesperson for the collaboration along with Ramona Vogt from DOE’s Lawrence Livermore National Laboratory. “Our framework will also provide a foundation for using heavy-flavor particles as a probe at the future  (EIC). Future experiments at the EIC will probe different forms of cold nuclear matter which are the precursors of the QGP in the laboratory,” Petreczky said.

In heavy-ion collisions at RHIC and the LHC, heavy charm and bottom quarks are produced upon initial impact of the colliding nuclei. Their large masses cause a diffusive motion that can serve as a marker of the interactions in the QGP, including the fundamental process of quarks binding together to form composite particles called hadrons.

“The framework needs to describe these particles from their initial production when the nuclei first collide, through their subsequent diffusion through the QGP and hadroniziation,” Petreczky said. “And these descriptions need to be embedded into realistic numerical simulations that enable quantitative comparisons to experimental data.”

The HEFTY collaboration will receive $2.5 Million from the DOE Office of Science, Office of Nuclear Physics, over five years. That funding will provide partial support for six graduate students and three postdoctoral fellows at 10 institutions, as well as a senior staff position at one of the national laboratories. It will also establish a bridge junior faculty position at �鶹��ѡ.