Vector-Isovector Excitations at Finite Density and Temperature and the Validity of Brown-Rho Scaling

Xiangdong Li C. M. Shakin

Published 2005-10-17, updated 2005-10-31Version 3

Recent work reported at the Quark Matter Conference 2005 has led to the suggestion that Brown-Rho scaling is ruled out by the NA60 data. (Brown-Rho scaling describes the reduction of hadronic masses in matter and at finite temperature.) In the present work we argue that the interpretation of the experimental data presented at the Quark Matter Conference is not correct and that Brown-Rho scaling is valid. To make this argument we discuss the evolution in time of the excited hadronic system and suggest that the system is deconfined at the earliest times and becomes confined when the density and temperature decrease as the system evolves. Thus, we suggest that we see both the properties of the deconfined and confined systems in the experimental data. In our interpretation, Brown-Rho scaling refers to the later times of the collision, when the system is in the confined phase.