CAREER: Spectral Properties of Hot and Dense QCD Matter (Ralf Rapp)
More than 99% of the mass of matter around us is concentrated in atomic nuclei, which are made of protons and neutrons. The elementary building blocks of these (and other ``hadrons") are believed to be (almost) massless ``quarks" and ``gluons". However, quarks and gluons have never been observed in isolation, and their strong interaction is responsible for generating the masses of the hadrons. The origin of these phenomena is among the main questions in modern nuclear physics. Under extreme conditions of temperature and density, hadrons are expected to dissolve into a new state of matter, the ``Quark-Gluon Plasma", which probably existed in the early universe a few microseconds after its birth. One of the key objectives in Dr. Rapp's research plan is to investigate how hadrons change their spectral properties (such as masses and decay widths) in hot and dense matter, and how this relates to phase changes into a Quark-Gluon Plasma. His calculations will be applied to experiments at the Relativistic Heavy-Ion Collider at Brookhaven National Laboratory, where gold nuclei are collided at high energy to recreate, for a short moment, the Quark-Gluon Plasma. To meet the challenge of identifying signatures of this transient state, Dr. Rapp will evaluate decay products of unstable particles allowing access to modifications of their spectral properties. He will pursue similar approaches to electron scattering experiments off nuclei at Jefferson Laboratory, as well as to cold dense quark matter which could prevail in compact stellar objects, so-called neutrons stars. In addition, Dr. Rapp will build a vigorous educational program for graduate and undergraduate students, including continued engagement in the NSF-funded REU site at the Cyclotron Institute. He will endeavor to broaden the general interest and education in modern nuclear science via a ``Saturday Morning Physics" program at Texas A&M University for high school students from a greater area around College Station, which is particularly suitable to enhance the involvement of minority groups, and to improve prospective undergraduate enrollment in physics.
