We present a relativistic three-body equation to study correlations in a medium of finite temperatures and densities. This equation is derived within a systematic Dyson equation approach and includes the dominant medium effects due to Pauli blocking and self energy corrections. Relativity is implemented utilizing the light front form. The equation is solved for a zero-range force for parameters close to the confinement-deconfinement transition of QCD. We present correlations between two- and three-particle binding energies and calculate the three-body Mott transition.Comment: 7 pages, 7 figure

We calculate the shear viscosity η in the quark-gluon plasma (QGP) phase within a virial expansion approach with particular interest in the ratio of η to the entropy density s, i.e. η/s. The virial expansion approach allows us to include the interactions between the partons in the deconfined phase and to evaluate the corrections to a single-particle partition function. In the latter approach we start with an effective interaction with parameters fixed to reproduce thermodynamical quantities of QCD such as energy and/or entropy density. We also directly extract the effective coupling αV for the determination of η. Our numerical results give a ratio η/s ≈ 0.097 at the critical temperature Tc, which is very close to the theoretical bound of 1/(4π). Furthermore, for temperatures T ≤ 1.8Tc the ratio η/s is in the range of the present experimental estimates 0.1 − 0.3 at RHIC. When combining our results for η/s in the deconfined phase with those from chiral perturbation theory or the resonance gas model in the confined phase we observe a pronounced minimum of η/s close to the critical temperature Tc.PACS. 12.38.Mh Quark-gluon plasma -25.75.Nq Phase transition in Quark-gluon plasma -21.65.Qr Quark matter/nuclear matter -51.20.+d Viscosity, diffusion, and thermal conductivity

We describe recent three-flavor QCD lattice data for the pressure, speed of sound and interaction measure at nonzero temperature and vanishing chemical potential within a virial expansion. For the deconfined phase we use a phenomenological model which includes non-perturbative effects from dimension two gluon condensates that reproduce the free energy of quenched QCD very well. The hadronic phase is parameterized by a generalized resonance-gas model. Furthermore, we extend this approach to finite quark densities introducing an explicit µ-dependence of the interaction. We calculate pressure, quark-number density, entropy and energy density and compare to results of lattice calculations. We, additionally, investigate the structure of the phase diagram by calculating the isobaric and isentropic lines as well as the critical endpoint in the (T, µq)-plane.

Abstract. We investigate the stability of the relativistic three-boson system with a zero range force in the light front form. In particular we study the dependence of the system on an invariant cut-off. We discuss the conditions for the relativistic Thomas collapse. Finally, we fix the parameters of the model introducing a scale.

Abstract. We present a relativistic three-body equation to study the stability of the isolated three-body system and the correlations in a medium of finite temperatures and densities. Relativity is implemented utilizing the light front form. Using a zero-range force we find the relativistic analog of the Thomas collapse and investigate the possibility that the nucleon exists as a Borromean system. Within a systematic Dyson equation approach we calculate the three-body Mott transition and the critical temperature of the color-superconducting phase.