Abstract
We extract the bulk viscosity of hot quark–gluon matter in the presence of light quarks from the recent lattice data on the QCD equation of state. For that purpose we extend the sum rule analysis by including the contribution of light quarks. We also discuss the universal properties of bulk viscosity in the vicinity of a second-order phase transition, as it might occur in the chiral limit of QCD at fixed strange quark mass and most likely does occur in two-flavor QCD. We point out that a chiral transition in the O(4) universality class at zero baryon density as well as the transition at the chiral critical point which belongs to the Z(2) universality class both lead to the critical behavior of bulk viscosity. In particular, the latter universality class implies the divergence of the bulk viscosity, which may be used as a signature of the critical point. We discuss the physical picture behind the dramatic increase of bulk viscosity seen in our analysis, and devise possible experimental tests of related phenomena.
Highlights
It was pointed out that bulk viscosity in SU(3) gluodynamics rises dramatically in the vicinity of the deconfinement phase transition [1]
Is this behavior specific for the first order phase transition in SU(3) gluodynamics? What is the “microscopic” dynamics responsible for the growth of bulk viscosity? Can this growth be classified in terms of the general theory of critical phenomena? Can it be used in the experimental studies to isolate the signatures of phase transitions in heavy ion collisions? In this paper we address these questions by generalizing the previous analysis to the case of QCD with two light quarks and a strange quark, which is of direct relevance to heavy ion experiments
In the vicinity of the chiral critical point at finite baryon density, the critical behavior is in the Z(2) universality class. This means that the bulk viscosity should diverge at T = Tc
Summary
It was pointed out that bulk viscosity in SU(3) gluodynamics rises dramatically in the vicinity of the deconfinement phase transition [1]. [1, 3], and the lattice observables used as an input, are quite different, this agreement indicates that the dramatic growth (by about three orders of magnitude!) of bulk viscosity in the vicinity of the deconfinement phase transition is a prominent feature of SU(3) gluodynamics. In the vicinity of the chiral critical point at finite baryon density, the critical behavior is in the Z(2) universality class This means that the bulk viscosity should diverge at T = Tc. This means that the bulk viscosity should diverge at T = Tc This behavior should manifest itself in heavy ion collisions through the decrease of average transverse momentum of produced particles, accompanied by the increase in total multiplicity. We argue that the rapid growth of bulk viscosity favors the scenario of “soft statistical hadronization” in which the expanding system hadronizes at the phase transition by producing a large number of color screening soft partons
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
