Mapping Deconfinement with a Compact Star Phase Diagram

We have found correlations between properties of the equation of state for stellar matter with a phase transition at supernuclear densities and two characteristic features of a "phase diagram" for rotating compact stars in the angular velocity - baryon number plane: 1) the critical dividing line between mono- and two-phase star configurations and 2) the maximum mass line. The second line corresponds to the minimum mass function for black hole candidates whereas the first one is observable by a population statistics, e.g. for Z-sources in low-mass X-ray binaries. The observation of a population gap in the mass distribution for the latter is suggested as an astrophysical verification of the existence of a first order phase transition in QCD at high densities such as the deconfinement.Comment: 4 pages, 2 figures, Contribution to Proceedings of Quark Matter 2002, Nantes, July 18 - 24, 200

Timing evolution of accreting strange stars

It has been suggested that the QPO phenomenon in LMXB's could be explained when the central compact object is a strange star. In this work we investigate within a standard model for disk accretion whether the observed clustering of spin frequencies in a narrow band is in accordance with this hypothesis. We show that frequency clustering occurs for accreting strange stars when typical values of the parameters of magnetic field initial strength and decay time, accretion rate are chosen. In contrast to hybrid star accretion no mass clustering effect is found.Comment: 10 pages, 3 figures, version accepted for publication in New Astronom

Mott dissociation of D-mesons at the chiral phase transition and anomalous J/Psi suppression

We investigate the in-medium modification of the charmonium breakup processes due to the Mott-effect for D-mesons at the chiral phase transition. A model calculation for the process J/Psi+pi --> D+D^*+ h.c. is presented which demonstrates that threshold effects in the thermal averaged breakup cross section can be explained as a Mott transition where final state quark-antiquark bound states enter the continuum of resonant states at the QCD phase transition. Applications to heavy-ion collisions within a modified Glauber model scenario and the phenomenon of anomalous J/$\psi$ suppression in the CERN NA50 experiment are addressed.Comment: 5 pages, 4 figures, uses JHEP.cls styl

Color neutrality effects in the phase diagram of the PNJL model

The phase diagram of a two-flavor Polyakov loop Nambu-Jona-Lasinio model is analyzed imposing the constraint of color charge neutrality. Main effects of this constraint are a shrinking of the chiral symmetry breaking (chiSB) domain in the T-mu plane, a shift of the critical point to lower temperatures and a coexistence of chiSB and two-flavor superconducting phases. The effects can be understood in view of the presence of a nonvanishing color chemical potential mu_8, which is necessary to compensate the color charge density rho_8 induced by the nonvanishing Polyakov-loop mean field phi_3.Comment: 8 pages, 4 figures, figures added, minor text modification

Medium induced Lorentz symmetry breaking effects in nonlocal PNJL models

In this paper we detail the thermodynamics of two flavor nonlocal Polyakov-Nambu-Jona-Lasinio models for different parametrizations of the quark interaction regulators. The structure of the model is upgraded in order to allow for terms in the quark selfenergy which violate Lorentz invariance due to the presence of the medium. We examine the critical properties, the phase diagram as well as the equation of state. Furthermore, some aspects of the Mott effect for pions and sigma mesons are discussed explicitly within a nonlocal Polyakov-Nambu-Jona-Lasinio model. In particular, we continued the meson polarization function in the complex energy plane and under certain approximations, we were able to extract the imaginary part as a function of the meson energy. We were not able to calculate the dynamical meson mass, and therefore resorted to a technical study of the temperature dependence of the meson width by replacing the meson energy with the temperature dependent spatial meson mass. Our results show that while the temperature behavior of the meson widths is qualitatively the same for a wide class of covariant regulators, the special case where the nonlocal interactions are introduced via the instanton liquid model singles out with a drastically different behavior.Comment: version to match the one published in PR