Transformation of the hadronic and subhadronic substances under extreme conditions

Abstract

Very dense and/or hot hadronic substance (e.g. the one with energy density greatly exceeding that of a normal nucleus) transforms itself into a subhadronic substance which obeys macroscopic classical physics, in particular suffers phase transitions. The most popular Single Phase Transition Model (SPTM) assumes that the new phase is the Quark Gluon Plasma (QGP) consisting of deconfined, chiral symmetric, pointlike "current" quarks q and gluons g of Quantum Chromodynamics (QCD). This paper is devoted to another, Double Phase Transition Model (DPTM) according to which hadronic substance (H) and QGP transform one into another via an intermediate phase consisting of deconfined constituent massive quarks Q which for brevity sake we call also equivalently valons (Q, valonic phase) with broken chiral symmetry (plus pions as Goldstone particles). I. e. we consider the phase transformation chain H-Q-QGP instead of usually assumed H-QGP. The phase transition H-Q is the Hagedorn one and corresponds to the Hagedorn temperature. Connection with the relativistic heavy ion collision is discussed. H-Q transformation may take place even at low (e.g. Dubna) energies.