Strangeness and charm at FAIR

TL;DR

This paper investigates the behavior of strange and charm mesons in hot, dense matter relevant to FAIR experiments, revealing how their spectral functions and resonances are modified in such environments.

Contribution

It provides a self-consistent coupled-channel analysis of mesons in hot dense matter, including finite temperature effects and meson self-energies, which is novel for FAIR conditions.

Findings

$ar K$ spectral function broadens, indicating resonance melting.

Charm mesons' resonances remain near free-space positions but gain width.

$D$ meson spectral density broadens with density, especially at lower energies.

Abstract

We study the properties of strange and charm mesons in hot and dense matter within a self-consistent coupled-channel approach for the experimental conditions of density and temperature expected for the CBM experiment at FAIR/GSI. The in-medium solution at finite temperature accounts for Pauli blocking effects, mean-field binding on all the baryons involved, and meson self-energies. In the strange sector, the $\bar K$ spectral function spreads over a wide range of energies, reflecting the melting of the $\Lambda (1405)$ resonance and the contribution of $(\Lambda,\Sigma,\Sigma^*)N^{-1}$ components at finite temperature. In the case of charm mesons, the dynamically-generated $\Lambda_c(2593)$ and $\Sigma_c(2880)$ resonances remain close to their free-space position while acquiring a remarkable width. As a result, the $D$ meson spectral density shows a single pronounced peak for energies close to the $D$ meson free-space mass that broadens with increasing matter density with an extended tail particularly towards lower energies. We also discuss the implications for the $D_{s0}(2317)$, $D_0(2400)$ and the predicted X(3700) resonances at FAIR energies.