rho ->pi pi decay in nuclear medium

摘要

We calculate the medium modifications of the rho pi pi vertex in a relativistic hadronic framework incorporating nucleons and Delta (1232) isobars, and find a substantial increase of the rho pi pi coupling, dominated by processes where the Delta is excited. The coupling depends significantly on the virtuality of the rho, which is related to analytic properties of the vertex function. We analyze the general case of a nonzero three-momentum of the rho with respect to the nuclear medium, and evaluate the resulting widths and spectral strength in the transverse and longitudinal channels for the rho --> pi pi decay. These widths are used to obtain the dilepton yields from rho decays in relativistic heavy-ion collisions. (C) 2001 Elsevier Science B.V. All rights reserved. [References: 88]