Metastable quark-antiquark droplets within the Nambu–Jona-Lasinio model

Abstract

Chemically nonequilibrated quark-antiquark matter is studied within the Nambu-Jona-Lasinio model. The equations of state of nonstrange (qϭu,d) and strange (qϭs) qq systems are calculated in the mean-field approximation. The existence of metastable bound states with zero pressure is predicted at finite densities and temperatures TՇ50 MeV. It is shown that the minimum energy per particle occurs for symmetric systems, with equal densities of quarks and antiquarks. At Tϭ0 these metastable states have quark number densities of about 0.5 fm Ϫ3 for qϭu,d and of 1 fm Ϫ3 for qϭs. A first order chiral phase transition is found at finite densities and temperatures. The critical temperature for this phase transition is approximately 75 MeV ͑90 MeV͒ for the nonstrange ͑strange͒ baryon-free quark-antiquark matter. For realistic choices of parameters, the model does not predict a phase transition in chemically equilibrated systems. Possible decay channels of the metastable qq droplets and their signatures in relativistic heavy-ion collisions are discussed. ͓S0556-2813͑99͒00406-9͔ PACS number͑s͒: 12.38. Mh, 11.30.Qc, 12.39.Fe, 25.75.Ϫq 1 Lattice calculations show that at temperatures TՇ150 MeV the gluons acquire a large effective mass due to the color screening effects. In the present work, dealing mostly with such moderate temperatures, we assume that gluonic degrees of freedom are suppressed.

On Dark Matter Identification

“…In comparison to the QGP energy interval, however, the nonstationary effects become more important and have also been observed [3] [4] [5] [7] [11]. It would therefore be interesting to study the chemical non-equilibrium and spatial correlation effects on QCD and the corresponding effective models, and on the possible role of magnetic monopoles in quark confinement.…”

“…Because the density of quarks has increased relative to that of antiquarks [2]. Chemical non equilibrium effects have also been observed in high-energy collisions [3] [4] [5] and been described using the Nambu-Jona-Lasinio model and other effective models [6]- [11] as a starting point for studying the quark-gluon plasma (QGP) and the chiral symmetry breakdown at the QCD phase transition.…”

Enhanced binding and cold compression of nuclei due to admixture of antibaryons

“…At such high densities nucleons might have to be substituted by quark degrees of freedom or modified by an admixture of them. Recently, we have used an extended version of the Nambu-Jona-Lasinio model to study bulk properties of systems composed of quarks and antiquarks [20]. It has been found that deeply bound states also appear in this model, but the corresponding binding energies are considerably smaller by about a factor of 3.…”

Strange-quark matter within the Nambu-Jona-Lasinio model

“…Let a p; (b p; ) and a + p; (b + p; ) be the destructi on and creati on operators ofa quark (an anti quark) i n the state p; ,w here p i s the 3-m om entum and i s the di screte quantum num ber denoti ng spi n and avour (col or i ndi ces are suppressed). It can be show n [ 18] that quark and anti quark phase{space occupati on num bers coi nci de w i th the Ferm i {D i rac di stri buti on functi ons:…”

“…In the previ ous papers [ 18,19] we have used the N JL m odel to study properti es of the quark{anti quark pl asm a outofchem i calequi l i bri um . In fact,we consi dered a system w i th i ndependent densi ti es ofquarks and anti quarks.…”