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Berndt Müller - One of the best experts on this subject based on the ideXlab platform.

  • Viscous leptons in the Quark Gluon Plasma
    Physical Review D, 2015
    Co-Authors: Berndt Müller, Di-lun Yang
    Abstract:

    We investigate the shear viscosity of leptons in a strongly coupled Quark Gluon Plasma. We find that the shear viscosity due to the lepton-Quark scattering is inversely proportional to the ratio of electric conductivity of the Quark Gluon Plasma to temperature up to the leading logarithmic order of the electromagnetic coupling. The finding implies that the thermal leptons form a more viscous fluid than the Quarks by a large ratio. Using the known result for the electrical conductivity of strongly coupled Plasmas obtained from gauge/gravity duality, we find that the lepton shear viscosity is suppressed compared with the one from lepton-lepton scattering. Consistently, we find an enhancement of the energy loss of hard leptons in a strongly coupled scenario compared with that in a weakly coupled Plasma.

  • From Quark-Gluon Plasma to the Perfect Liquid
    arXiv: Nuclear Theory, 2007
    Co-Authors: Berndt Müller
    Abstract:

    After reviewing some basic concepts of the theory of strongly interacting matter above nuclear energy density and reviewing some salient results of the experimental program at the Relativistic Heavy Ion Collider (RHIC), these lectures explain why the Quark-Gluon Plasma observed in the RHIC experiments has been called a ``perfect liquid.'' They then give an introduction to some recent ideas concerning the possible origin of the nearly inviscid nature of the Quark-Gluon Plasma and discuss the connection between low viscosity and strong parton energy loss of hot QCD matter.

  • Signatures for the Quark-Gluon Plasma
    Nuclear Physics, 1998
    Co-Authors: Berndt Müller
    Abstract:

    Abstract I survey the experimental signatures of a Quark-Gluon Plasma in the light of present and future experiments. This includes a review of new theoretical results concerning the QCD equation of state and the formation of a dense parton Plasma in high energy nuclear collisions.

  • the search for the Quark Gluon Plasma
    Annual Review of Nuclear and Particle Science, 1996
    Co-Authors: John W. Harris, Berndt Müller
    Abstract:

    ▪ Abstract We provide an overview of the present understanding of the transition from hadrons to a Quark-Gluon Plasma, its signatures, and the experimental results so far. We discuss results of numerical simulations of the lattice gauge theory and critically evaluate the various observables that have been proposed as signatures of the QCD phase transition. We place the existing data from relativistic heavy-ion experiments at the Brookhaven Alternating Gradient Synchrotron (AGS) and CERN Super Proton Synchrotron (SPS) into perspective and provide an overview of the techniques and strategies that will be employed in the search for the Quark-Gluon Plasma at heavy-ion colliders, such as the Relativistic Heavy-Ion Collider (RHIC) and the Large Hadron Collider (LHC).

  • The Search for the Quark-Gluon Plasma
    Annual Review of Nuclear and Particle Science, 1996
    Co-Authors: John W. Harris, Berndt Müller
    Abstract:

    We provide an overview of the present understanding of the transition from hadrons to a Quark-Gluon Plasma, its signatures, and the experimental results so far. We discuss results of numerical simulations of the lattice gauge theory and critically evaluate the various observables that have been proposed as signatures of the QCD phase transition. We place the existing data from relativistic heavy ion experiments at the Brookhaven AGS and CERN SPS into perspective and provide an overview of the techniques and strategies that will be employed in the search for the Quark-Gluon Plasma at heavy ion colliders, such as RHIC and the LHC.

Markus H. Thoma - One of the best experts on this subject based on the ideXlab platform.

  • Wakes in a Collisional Quark-Gluon Plasma
    Journal of Physics G: Nuclear and Particle Physics, 2007
    Co-Authors: Purnendu Chakraborty, Munshi G. Mustafa, Rajarshi Ray, Markus H. Thoma
    Abstract:

    Wakes created by a parton moving through a static and infinitely extended Quark-Gluon Plasma are considered. In contrast to former investigations collisions within the Quark-Gluon Plasma are taken into account using a transport theoretical approach (Boltzmann equation) with a Bhatnagar-Gross-Krook collision term. Within this model it is shown that the wake structure changes significantly compared to the collisionless case.

  • Complex Plasmas as a Model for the Quark-Gluon-Plasma Liquid
    Nuclear Physics A, 2006
    Co-Authors: Markus H. Thoma
    Abstract:

    The Quark-Gluon Plasma, possibly created in ultrarelativistic heavy-ion collisions, is a strongly interacting many-body parton system. By comparison with strongly coupled electromagnetic Plasmas (classical and non-relativistic) it is concluded that the Quark-Gluon Plasma could be in the liquid phase. As an example for a strongly coupled Plasma, complex Plasmas, which show liquid and even solid phases, are discussed briefly. Furthermore, methods based on correlation functions for confirming and investigating the Quark-Gluon-Plasma liquid are presented. Finally, consequences of the strong coupling, in particular a cross section enhancement in accordance with experimental observations at RHIC, are discussed.

  • Structure functions and pair correlations of the Quark-Gluon Plasma
    Physical Review D, 2005
    Co-Authors: Markus H. Thoma
    Abstract:

    Recent experiments at RHIC and theoretical considerations indicate that the Quark-Gluon Plasma, present in the fireball of relativistic heavy-ion collisions, might be in a liquid phase. The liquid state can be identified by characteristic correlation and structure functions. Here definitions of the structure functions and pair correlations of the Quark-Gluon Plasma are presented as well as perturbative results. These definitions might be useful for verifying the Quark-Gluon-Plasma liquid in QCD lattice calculations.

  • Screening of a moving parton in the Quark-Gluon Plasma
    Physical Review C, 2005
    Co-Authors: Munshi G. Mustafa, Markus H. Thoma, Purnendu Chakraborty
    Abstract:

    The screening potential of a parton moving through a Quark-Gluon Plasma is calculated using semiclassical transport theory. An anisotropic potential showing a minimum in the direction of the parton velocity is found. As consequences possible new bound states in the Quark-Gluon Plasma and J/{psi} dissociation are discussed.

  • The Quark-Gluon-Plasma Liquid
    arXiv: High Energy Physics - Phenomenology, 2004
    Co-Authors: Markus H. Thoma
    Abstract:

    The Quark-Gluon Plasma close to the critical temperature is a strongly interacting system. Using strongly coupled, classical, non-relativistic Plasmas as an analogy, we argue that the Quark-Gluon Plasma is in the liquid phase. This allows to understand experimental observations in ultrarelativistic heavy-ion collisions and to interpret lattice QCD results. It also supports the indications of the presence of a strongly coupled QGP in ultrarelativistic heavy-ion collisions.

M. A. Lisa - One of the best experts on this subject based on the ideXlab platform.

Jean-paul Blaizot - One of the best experts on this subject based on the ideXlab platform.

  • thermodynamics of the high temperature Quark Gluon Plasma
    arXiv: High Energy Physics - Phenomenology, 2003
    Co-Authors: Jean-paul Blaizot, Edmond Iancu, Anton Rebhan
    Abstract:

    We review the various methods which have been employed recently to describe the thermodynamics of the high temperature Quark-Gluon Plasma using weak coupling techniques, and we compare their results with those of most recent lattice gauge calculations. Many of the difficulties encountered with perturbation theory at finite temperature are in fact not specific to QCD but are present in any field theory at finite temperature and will be discussed first in the simple example of the scalar field theory. We discuss the merits and limitations of various techniques which have been used to go beyond perturbation theory in the soft sector, such as dimensional reduction, screened perturbation theory or hard-thermal-loop perturbation theory, and Phi-derivable approximations. In the last part of the review, we focus on the later, which lead to a remarkably simple expression for the entropy of the Quark-Gluon Plasma. When complemented with further, physically motivated, approximations, this approach reproduces accurately the entropy obtained from lattice gauge calculations at temperatures above 2.5 T_c, where T_c is the deconfinement temperature. This calculation thus provides also support to the physical picture of the Quark-Gluon Plasma as a gas of weakly interacting quasiparticles.

  • The Entropy of the Quark-Gluon Plasma
    Nuclear Physics A, 2002
    Co-Authors: Jean-paul Blaizot
    Abstract:

    The entropy of the Quark-Gluon Plasma can be calculated from QCD using (approximately) self-consistent approximations. Lattice results for pure gauge theories are accurately reproduced down to temperatures of the order of 2.5$T_c$. Comparisons with other approaches to the thermodynamics of the Quark-Gluon Plasma are briefly discussed.

  • Theory of the Quark-Gluon Plasma
    arXiv: High Energy Physics - Phenomenology, 2001
    Co-Authors: Jean-paul Blaizot
    Abstract:

    These lectures are an introduction to recent developments in the study of the high temperature phase of QCD by using weak coupling techniques. After a brief introduction to some techniques of quantum field theory at finite temperature, I proceed to an analysis of the various important scales and degrees of freedom of the Quark-Gluon Plasma and focus on the effective theory for the collective modes which develop at the particular momentum scale $gT$, where $g$ is the gauge coupling and $T$ the temperature. A powerful technique to construct the effective theory is based on kinetic equations which govern the dynamics of the hard degrees of freedom. Some of the collective phenomena that are described by this effective theory are briefly mentioned. Then I turn to the calculation of the entropy of the Quark-Gluon Plasma and show how the information coded in the effective theory can be exploited in (approximately) self-consistent calculations.

  • The Quark-Gluon Plasma
    Nuclear Physics A, 1993
    Co-Authors: Jean-paul Blaizot
    Abstract:

    Abstract I present various aspects of the physics of the Quark-Gluon Plasma. Known properties of the transition from hadronic matter to the Quark-Gluon Plasma are recalled. Progress in the phenomenology of ultra-relativistic heavy ion collisions is discussed on two examples. Some recent theoretical developments are mentioned.

Francesco Becattini - One of the best experts on this subject based on the ideXlab platform.