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Medium Dependence of the Vector-Meson Mass: Dynamical and/or Brown-Rho Scaling?

G. E. Brown·G. Q. Li·R. Rapp·M. Rho·J. Wambach
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Abstract

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 $\sim$~$m_ρ/2$ 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''.

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G. E. Brown, G. Q. Li, R. Rapp, M. Rho, J. Wambach. 1998-06-09. Medium Dependence of the Vector-Meson Mass: Dynamical and/or Brown-Rho Scaling?. https://arxiv.org/abs/nucl-th/9806026

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