1998/06/09 by G. E. Brown, G. Q. Li, R. Rapp +2
Physics and Astronomy · #nucl-th #hep-ph
published as Acta Phys.Polon. B29 (1998) 2309-2321 · 13 pages LaTeX, incl. 5 eps-figures and appb.sty; Talk given at the Workshop on 'The Structure of Mesons, Baryons and Nuclei', Cracow, May 1998, in honor of J. Speth's 60th birthday, to be published in Acta Physica Polonica B
arxiv created 1998/06/09 · arxiv updated 2009/11/30
We discuss the similarities and differences for the theories of Rapp, Wambach and collaborators (called R/W in short) and those based on Brown-Rho scaling (called B/R), as applied to reproduce the dileptons measured by the CERES collaboration in the CERN experiments. In both theories the large number of dileptons at invariant masses ∼~mρ/2 are shown to be chiefly produced by a density-dependent ρ-meson mass. In R/W the medium dependence is dynamically calculated using hadronic variables defined in the matter-free vacuum. In B/R scaling it follows from movement towards chiral symmetry restoration due to medium-induced vacuum change, and is described in terms of constituent (or quasiparticle) quarks. We argue that the R/W description should be reliable up to densities somewhat beyond nuclear density, where hadrons are the effective variables. At higher density there should be a crossover to constituent quarks as effective variables scaling according to B/R. In the crossover region, the two descriptions must be ``dual''.