Massive constituent quarks and unified description of freeze-out parameters: does QGP form at low temperature?

Abstract

The possibility of unified description of hadron multiple production in heavy ion collisions over the wide energy interval, from few hundreds MeV/n at GSI/SIS through 11 GeV/n at BNL/AGS up to 160 GeV/n at CERN/SPS, has been emphasized recently by J. Cleymans and K. Redlich. They, and somewhat later B. Muller and J. Rafelski, treated this fact as an indication that quark-gluon plasma (QGP) can be produced even at very low energies of impinging nuclei. In our opinion, it rather witnesses that a massive constituent quark (valon) - not massless current quark and gluon! - is just what becomes "quite easily" to be unbound, and thus supports the expectation that in course of compression and heating from hadronic state to QGP (or, vice versa, of expansion and cooling down from QGP to hadronic state) nuclear matter should pass through an intermediate phase in between.