Accessibility of color superconducting quark matter phases in heavy-ion collisions

Abstract

We discuss a hybrid equation of state (EoS) that fulfills constraints for mass-radius relationships and cooling of compact stars. The quark matter EoS is obtained from a Polyakov-loop Nambu-Jona-Lasinio (PNJL) model with color superconductivity, and the hadronic one from a relativistic meanfield (RMF) model with density-dependent couplings (DD-RMF). For the construction of the phase transition regions we employ here for simplicity a Maxwell construction. We present the phase diagram for symmetric matter which exhibits two remarkable features: (1) a "nose"-like structure of the hadronic-to-quark matter phase border with an increase of the critical density at temperatures below T ∼ 150 MeV and (2) a high critical temperature for the border of the two-flavor color superconducting (2SC) phase, T c > 160 MeV. We show the trajectories of heavy-ion collisions in the plane of excitation energy vs. baryon density calculated using the UrQMD code and conjecture that for incident energies of 4 . . . 8 A GeV as provided, e.g., by the Nuclotron-M at JINR Dubna or by lowest energies at the future heavy-ion collision experiments CBM@FAIR and NICA@JINR, the color superconducting quark matter phase becomes accessible.

Phase diagram of hot magnetized two-flavor color-superconducting quark matter

“…in Fig I for ẽB > ẽB t ≃ 0.5 GeV 2 . This could be relevant in relation with the question addressing the accessibility of 2SC phase in present or future heavy ion experiments, which is recently posed in [32]. We have extended the setup of the model used in [32] by considering the effect of constant magnetic fields, which are supposed to be created in the non-central heavy ion collisions [28] and are estimated to be of order ẽB ≃ 0.03 GeV 2 at RHIC energies, and ẽB ≃ 0.3 GeV 2 at LHC 19 See Footnote 9.…”

“…We are in particular interested on the additional effects of finite temperature, and, will focus on possible interplay between T, µ and ẽB on the formation of chiral and color symmetry breaking condensates and on the nature of phase transitions. Our results may be relevant for the physics of heavy ion collisions, where, recently the question of accessibility of color superconducting quark matter phases is pointed out [32]. The authors in [32] use a Polyakov-NJL (PNJL) model at finite temperature and density and present the corresponding QCD phase diagram including, among others, mixed phase regions of first order transition of 2SC-CFL quark matter and second order 2SC-normal phase transition.…”

“…Our results may be relevant for the physics of heavy ion collisions, where, recently the question of accessibility of color superconducting quark matter phases is pointed out [32]. The authors in [32] use a Polyakov-NJL (PNJL) model at finite temperature and density and present the corresponding QCD phase diagram including, among others, mixed phase regions of first order transition of 2SC-CFL quark matter and second order 2SC-normal phase transition. From this phase diagram, they conclude that color superconductor phase is already accessible at the present nuclotron-M energies 4 < E < 8 AGeV, and, that possible transition from 2SC to normal quark matter becomes attainable in the planned FAIR-CBM and NICA-MPD experiments at 2 < E < 40 AGeV.…”

Color neutral 2SC phase of cold and dense quark matter in the presence of constant magnetic fields

“…In [16], it is shown that the magnetic field presently created at RHIC is at most eB ≃ 1.3 m 2 π ∼ 4.3 × 10 18 Gauß, and the estimated value of the magnetic field strength for the LHC energy amounts to 15 m 2 π ∼ 5 × 10 19 Gauß. 3 Recently, the question of accessibility of the 2SC phase in the future heavy ion collision experiments is investigated in [17]. Here, the authors do not consider the effect of the before mentioned magnetic fields.…”

Nuclear liquid-gas phase transition at largeNcin the van der Waals approximation

“…Such matter can hopefully be produced in heavy ion collisions [1][2][3][4], and is thought to exhibit a rich phenomenology. The latter includes one [5] or more [6] critical points, spinodal instabilities [7], precursors to color superconductivity [8], separation between chiral symmetry and confinement [9][10][11][12][13][14] chirally inhomogeneus phases [15][16][17][18], new phases [19] etc.…”