Extracting squared speed-of-sound parameter from asymmetric nuclear collisions at high energies

Abstract

We apply the Landau hydrodynamic model in leading target/projectile nucleons and target/projectile cylinders in the multisource thermal model respectively, in asymmetric nuclear collisions. Each leading nucleon source or cylinder source is regarded as an energy reservoir to emit or produce particles and can be described by the Landau hydrodynamic model. The pseudorapidity distribution of final-state particles is in fact a sum of four Gaussian functions which correspond to the contributions of the leading target nucleons, target cylinder, projectile cylinder and leading projectile nucleons, respectively, in accordance with their central rapidities from low to high value. Based on the descriptions of the pseudorapidity distributions of final-state particles produced in proton-emulsion, deuteron-gold and gold-emulsion collisions, the squared speed-of-sound parameters for the four sources in asymmetric nuclear collisions have been extracted and shown to be approximately the same within the statistical error.