Impact of the in-medium conservation of energy on the π⁻/π⁺ multiplicity ratio

IFIN-HH, Reactorului 30, 077125 Măgurele-Bucharest, Romania

Published online: 11 May 2016

Abstract

An upgraded version of the isospin dependent T¨ubingen QMD transport model, which allows the conservation of the total energy, is presented. This is achieved by including in the energy-balance equations of the density, isospin asymmetry and momentum dependent inmedium baryon potential energies. It leads to an effective modification of particle production thresholds with respect to the vacuum ones. Compatible constraints for the symmetry energy stiffness from π⁻/π⁺ multiplicity ratio and elliptic flow experimental data of Au+Au collisions at 400 MeV/nucleon can be extracted in this case. However, an important dependence of the π⁻/π⁺ observable on the strength of the isovector part of the Δ(1232) isobar potential is also demonstrated. The present lack of information on this quantity prevents a precise extraction of the value for the symmetry energy stiffness employing the mentioned observable alone.