Hadronic modes in the quark plasma with an internal symmetry

Abstract

We show that requiring the quark partition function to be color singlet of SU (3) color gauge group leads to reordering the thermodynamic potential in terms of the colorless multi-quark modes (qq, qqq,qqq, · · ·) at any given temperature. These color singlet structures are not bound states in real sense, rather they are combination of constituents quarks only. In accord with the "preconfinement" property of QCD, under a suitable confining mechanism, these could evolve into color singlet hadrons/baryons at low temperatures. At fairly high temperatures these multi-quark color singlet structures exist in the plasma like hadronic modes, just as in the more familiar low temperature phase. This suggests that there exists a strong color correlation in the plasma at all temperatures.PACS numbers: 24.85.+p, 12.38.Mh, 25.75.+r, 64.60.Qb The success of the quark model, the quantum chromodynamics (QCD), and the non-observability of the free partons (q,q, g) has entailed the concept of confinement. QCD, the theory of strong interactions, is not perturbative at large distances. Thus, the confinement itself can not be treated perturbatively. There are reasons to believe that the confinement of partons inside hadrons may not survive collisions between heavy nuclei at relativistic energies [1]. One of the most interesting predictions of QCD at high temperature is the transition from the confined/chirally broken phase to deconfined/chirally symmetric state of quasi-free quarks and gluons, the so called quark-gluon plasma. At very high temperatures, the bulk properties (energy density, pressure, and entropy etc.) of QCD matter, seem to be described by a gas of nearly free quarks and gluons. However, it is also known that long range, non-perturbative effects disrupt this simple picture even at fairly high temperatures [2].Lattice calculations [3] have provided ample evidence * Alexander von Humboldt Fellow, and on leave from Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Calcutta -700 064, India.that the long distance behaviour of high temperature phase is characterised by the propagation of color singlet objects like multi-quark structures. The determination of the plasma screening length shows evidence of a kind of correlations in the quark-gluon plasma at all temperatures. Now what these structures are and how they show up is not yet very clear theoretically. Quite sometime ago an indication was made as a "precursor" to the confinement property of QCD by Amati and Veneziano [4] where the cascading and fragmenting partons produced in hadronic collisions rearrange themselves into color singlet clusters which ultimately evolve into hadrons [5,6]. These considerations convince us that it is important to incorporate the dynamic requirement of color singletness of the quark-matter to take into account such 'interaction' which "tunnels" into hadronic matter phase space [6].The purpose of the present study is to reconsider the statistical themodynamical description of quantum gases consisting of quarks and antiquarks, in suc...