Hadronic Rapidity Spectra in Heavy Ion Collisions at SPS and AGS energies in a Quark Combination Model

TL;DR

This paper applies a quark combination model to analyze hadron rapidity spectra in heavy ion collisions at SPS and AGS energies, successfully describing data at higher energies and exploring the energy dependence of quark spectra and strangeness.

Contribution

The study extends the quark combination model to SPS and AGS energies, providing a unified description of hadron spectra and insights into the onset of deconfinement.

Findings

Successfully describes hadron spectra at SPS energies.

Identifies the disappearance of quark-level correlations below the deconfinement threshold.

Analyzes the energy dependence of quark spectrum widths and strangeness production.

Abstract

The quark combination mechanism of hadron production is applied to nucleus-nucleus collisions at the CERN Super Proton Synchrotron (SPS) and BNL Alternating Gradient Synchrotron (AGS). The rapidity spectra of identified hadrons and their spectrum widths are studied. The data of $\pi^{-}$, $K^{\pm}$, $\phi$, $\Lambda$, $\bar{\Lambda}$, $\Xi^{-}$, and $\bar{\Xi}^{+}$ at 80 and 40 AGeV, in particular at 30 and 20 AGeV where the onset of deconfinement is suggested to happen, are consistently described by the quark combination model. However at AGS 11.6 AGeV below the onset the spectra of $\pi^{\pm}$, $K^{\pm}$ and $\Lambda$ can not be simultaneously explained, indicating the disappearance of intrinsic correlation of their production in the constituent quark level. The collision-energy dependence of the rapidity spectrum widths of constituent quarks and the strangeness of the hot and dense quark matter produced in heavy ion collisions are obtained and discussed.