Journal Club: Color Transparency

Fri., Jan. 28, 2022 3:30 p.m. - Fri., Jan. 28, 2022 4:30 p.m.

Location: Zoom

Abstract: At low energies, the strong interaction is well described in terms of nucleons exchanging mesons, whereas at high energies, perturbative quantum chromo-dynamics (pQCD) characterizes the strong force in terms of quarks and gluons carrying color charge. Although these two descriptions are well understood in their respective energy scales, the transition between them is not uniquely identified. Color Transparency (CT) is a prediction of QCD, wherein a hadron undergoing a hard (high-momentum transfer) interaction will be temporarily in a point-like state (i.e. reduced color dipole moment), and traverse the nuclear medium more readily than otherwise expected (i.e. the nuclear medium is more transparent). The onset of Color Transparency is a signature of QCD degrees of freedom in nuclei, and is expected to manifest as an increase in transparency with increasing momentum transfer. CT has been observed previously in a variety of high-energy nuclear reactions involving meson production, but has never been observed in reactions involving baryon emission. New results from Jefferson Lab Hall C, up to Q^2=14 GeV^2, were expected to be the first to observe CT in this regime. However, the results were surprisingly negative, imposing strict constraints on models of Color Transparency for protons. We will start with some slides describing Color Transparency in a non-technical manner, and summarize the experimental situation before looking at the new results.

Journal Article "Ruling out Color Transparency in Quasielastic 12C(e,e′p) up to Q^2 of 14.2 (GeV/c)^2"

Speaker: Dr. Garth Huber, University of Regina