Isospin Effects on Meson Production in Relativistic Heavy Ion Collisions

TL;DR

This paper explores how isospin effects influence meson production in relativistic heavy ion collisions, providing insights into the isovector interaction and potential signals of phase transitions at high densities.

Contribution

It offers a covariant, mean-field approach to study isospin effects on meson yields, highlighting sensitive observables and non-equilibrium phenomena in heavy ion collisions.

Findings

Pion/kaon yield ratios are sensitive to isospin effects.

Non-equilibrium effects significantly influence meson production.

Possible signatures of a transition to a mixed hadron-quark phase are discussed.

Abstract

We show that the phenomenology of isospin effects on heavy ion reactions at intermediate energies (few AGeV range) is extremely rich and can allow a ``direct'' study of the covariant structure of the isovector interaction in a high density hadron medium. We work within a relativistic transport frame, beyond a cascade picture, consistently derived from effective Lagrangians, where isospin effects are accounted for in the mean field and collision terms. We show that rather sensitive observables are provided by the pion/kaon production (\pi^-/\pi^+, K^0/K^+ yields). Relevant non-equilibrium effects are stressed. The possibility of the transition to a mixed hadron-quark phase, at high baryon and isospin density, is finally suggested. Some signatures could come from an expected ``neutron trapping'' effect.