We argue that quite unusual properties of Quark-Gluon Plasma in the RHIC temperature domain $T=(1-2)T_c$ are consequences of the approximate equilibrium between electric and magnetic sectors reached above the deconfinement temperature. Already classical study of few body motion in a electric-magnetic plasma shows abnormally large scattering rate due to the so called ``magnetic bottle'' effect. Molecular dynamics simulation have found that equal mixture of electric and magnetic quasiparticles do produce plasmas of small viscosity and even smaller diffusion rate, comparable to what is needed to explain RHIC data and also to what follows from AdS/CFT.
As a separate issue, we point out that right above $T_c$ there should be surviving s-wave baryons made of quarks ($N,Δ$), as well as adjoint objects, 3-gluon and 3-monopole chains (the latter being nothing else but ``calorons'' or finite-T instantons).
The double phase transition of hadronic matter, $H$, first, to the gas of deconfined constituent quarks (for brevity called {\it valons}), $Q$, and then, secondly, the phase transition from $Q$ to quark-gluon plasma, $QGP$, is considered within bag model ideology. In distinction from previous double phase transition investigations, it is not supposed that at zero chemical potential (~$μ=0$~) transition temperatures $T_d$ (for $H~\leftrightarrow~Q$) and $T_{ch}$ (for $Q~\leftrightarrow~ QGP$, chiral restoration) coincide. Then for plausible range of chosen bag constants, $B_Q$ for $Q$ and $B_q$…
We assume that the initial hydrodynamic environment is a Quark Gluon Plasma (QGP) phase where merely u and d quarks are considered when adding a magnetic field. When considering the chiral magnetic effect in relativistic heavy ion collisions, an anomalous current will be formed in the QGP environment. The chiral magnetic current formed by these u and d quarks has an impact on the heavy quarkonium. By using fluid/gravity duality, the metric with anomalous flow is established by using fluid/gravity duality, so as to introduce the magnetic field effect into the corresponding metric. And then we u…
We perform SU(3) Lattice Gauge Theory simulations of the deconfinement transition attempting to mimic conditions encountered in heavy ion collisions. Specifically, we perform a sudden temperature quench across the deconfinement temperature, and follow the response of the system in successive simulation sweeps under spatial lattice expansion and temperature fall-off. In measurements of the Polyakov loop and structure functions a robust strong signal of global instability response is observed through the exponential growth of low momentum modes. Development of these long range modes isotropizes …
Possible phase transition of strongly interacting matter from hadron to a Quark-Gluon Plasma (QGP) state have in the p ast received considerable interest. It has been suggested that this problem might be treated by percolation theory. Th e Color String Percolation Model (CSPM) is used to determine the equation of state (EOS) of the QGP produced in central Au-Au collisions at RHIC energies. The bulk thermodynamic quantities- energy density, entropy density and t he sound velocity- are obtained in the framework of CSPM. It is shown that the results are in excellent agreement with the recent latt…
We study the dynamics of first-order cofinement-deconfinement phase transition through nucleation of hadronic bubbles in an expanding quark gluon plasma in the context of heavy ion collisions for interacting quark and hadron gas and by incorporating the effects of curvature energy. We find that the interactions reduce the delay in the phase transition whereas the curvature energy has a mixed behavior. In contrast to the case of early Universe phase transition, here lower values of surface tension increase the supercooling and slow down the hadronization process. Higher values of bag pressure t…
According to extensive ab initio calculations of lattice QCD, the very large energy density available in heavy-ion collisions at SPS and now at RHIC must be sufficient to generate quark-gluon plasma (QGP), a new state of matter in the form of plasma of free quarks and gluons. The new state of matter discovered at RHIC seems to be perfect fluid rather than free plasma. Its shear viscosity is assumed to be almost zero. In this work, I first considered the theoretical and phenomenological consequences of this discovery and finally asked questions about the nature of phase transition and propertie…
We present a five-dimensional fully anisotropic holographic model for heavy quarks supported by Einstein-dilaton-three-Maxwell action; one of the Maxwell fields is related to an external magnetic field. Influence of the external magnetic field on the 5-dim black hole solution and the confinement/deconfinement phase diagram is considered. The effect of the inverse magnetic catalyses is revealed and positions of critical end points are found.
The recently proposed baryon-strangeness correlation (C_BS) is studied with a string-hadronic transport model (UrQMD) for various energies from E_lab=4 AGeV to \sqrt s=200 AGeV. It is shown that rescattering among secondaries can not mimic the predicted correlation pattern expected for a Quark-Gluon-Plasma. However, we find a strong increase of the C_BS correlation function with decreasing collision energy both for pp and Au+Au/Pb+Pb reactions. For Au+Au reactions at the top RHIC energy (\sqrt s=200 AGeV), the C_BS correlation is constant for all centralities and compatible with the pp result.…
Major aspects of the subhadronic state of nuclear matter populated with deconfined color particles are reviewed. At high and even at rather low nuclear collision energies, this is expected to be a short-term quark-gluon plasma (QGP), but, seemingly, not only this. Emphasis is put on the self-consistency requirement that must be imposed on any phenomenological description of the evolution of a hot and dense nuclear medium as it expands (cools down) to the point where the final scattering of secondary particles starts. The view is argued and analyzed that massive constituent quarks should then p…
We assess transport properties of heavy quarks in the Quark-Gluon Plasma (QGP) that show a strong non-perturbative behavior. A T-matrix approach based on a potential taken from lattice QCD hints at the presence of heavy-quark (HQ) resonant scattering with an increasing strength as the temperature, $T$, reaches the critical temperature, $T_c \simeq 170 \; \MeV$ for deconfinement from above. The implementation of HQ resonance scattering along with a hadronization via quark coalescence under the conditions of the plasma created in heavy-ion collisions has been shown to correctly describe both the…
One of the confident predictions of QCD is that at sufficiently high temperature and/or density, hadronic matter should undergo a thermodynamic phase transition to a colour deconfined state of matter - popularly called the Quark-Gluon Plasma (QGP). In low energy effective theories of Quantum Chromodynamics (QCD), one usually talks of the chiral transition for which a well defined order parameter exists. We investigate the dissociation of pions and kaons in a medium of hot quark matter decsribed by the Nambu - Jona Lasinio (NJL) model. The decay widths of pion and kaon are found to be large but…
We consider the dynamics of the scalar and pseudoscalar glueballs in the Quark-Gluon Plasma (QGP). By using the instanton model for the QCD vacuum we give the arguments that the nonperturbative gluon-gluon interaction is qualitatively different in the confinement and deconfinement phases. Based on this observation it is shown that above $T_c$ the values of the scalar and pseudoscalar glueball masses might be very small. The estimation of the temperature of scale invariance restoration, at which the scalar glueball becomes massless, is given. We also discuss the Bose-Einstein condensation of th…
Strangeness signature of of quark-gluon plasma (QGP) is central to the exploration of baryon-dense matter: the search for the critical point and onset of deconfinement. I report on the discovery of QGP by means of strangeness: The key historical figures and their roles in this quest are introduced and the experimental results obtained are discussed. The important role of antihyperons is emphasized. The statistical hadronization model, and sudden hadronization are described. Results of present day data analysis: strangeness and entropy content of a large fireball, and the universal hadronizatio…
The cross-over region of the quark-gluon plasma (QGP) created in heavy ion collisions is influenced by the nearby deconfinement, chiral and baryon condensation phase transitions. A characteristic signature of the deconfinement transition in this region can be infered using the flux tube model, which is dual to the Polyakov loop description and which offers a visual picture of what happens during the transition. The three-point (anti)vertices of a flux tube network lead to formation of (anti)baryons upon hadronisation. Since there is no fundamental interaction associated with the baryon number,…
The FASTSUM collaboration presents a study on the temperature dependence of the electrical conductivity $σ$ in the quark-gluon plasma, using the methods of lattice QCD. Correlators of the exactly conserved vector current are measured at different temperatures across the deconfinement transition, using ensembles of $2+1$ flavours of dynamical fermions on anisotropic lattices. We then employ bayesian methods (MEM) to extract the relevant spectral functions, which are found to be consistent with $σ/T$ rising as a function of $T$. The robustness of the results is verified by a detailed analysis of…
We investigate the shear viscosity of thermalized photons in the quark gluon plasma (QGP) at weak coupling and $\mathcal{N}=4$ super Yang-Mills plasma (SYMP) at both strong and weak couplings. We find that the shear viscosity due to the photon-parton scattering up to the leading order of electromagnetic coupling is suppressed when the coupling of the QGP/SYMP is increased, which stems from the blue-shift of the thermal-photon spectrum at strong coupling. In addition, the shear viscosity rapidly increases near the deconfinement transition in a phenomenological model analogous to the QGP.
Matrix models for the deconfining phase transition in $SU(N)$ gauge theories have been developed in recent years. With a few parameters, these models are able to reproduce the lattice results of the thermodynamic quantities in the semi-quark gluon plasma(QGP) region. They are also used to compute the behavior of the 't Hooft loop and study the exceptional group $G(2)$. In this paper, we review the basic ideas of the construction of these models and propose a new form of the non-ideal corrections in the matrix model. In the semi-QGP region, our new model is in good agreement with the lattice si…
We analyze longitudinal pion spectra from \sqrt{s_{NN}}= 2 GeV to \sqrt {s_{\rm NN}}=20 GeV within Landau's hydrodynamical model and the UrQMD hybrid approach. From the measured data on the widths of the pion rapidity spectra, we extract the sound velocity c_s^2 in the dense stage of the reactions. It is found that the sound velocity has a local minimum (indicating a softest point in the equation of state, EoS) at \sqrt{s_{NN}}= 4-9 GeV, an energy range accessible at the Facility for Antiproton and Ion Research (FAIR) as well as the RHIC-Beam Energy Scan (RHIC-BES). This softening of the EoS i…
The Color String Percolation Model (CSPM) is used to determine the equation of state (EOS) of the QGP produced in central Au-Au collisions at $\sqrt{s_{NN}}$ = 200 A GeV using STAR data at RHIC. When the initial density of interacting colored strings exceeds the 2D percolation threshold a cluster is formed, which defines the onset of color deconfinement. These interactions also produce fluctuations in the string tension which transforms the Schwinger particle (gluon) production mechanism into a maximum entropy thermal distribution. The single string tension is determined by identifying the kno…
The temperature and chemical potential dependent surface tension of bags is introduced into the gas of quark-gluon bags model. This resolves a long standing problem of a unified description of the first and second order phase transition with the cross-over. Such an approach is necessary to model the complicated properties of quark-gluon plasma and hadronic matter from the first principles of statistical mechanics. The suggested model has an exact analytical solution and allows one to rigorously study the vicinity of the critical endpoint of the deconfinement phase transition. The existence of …
This is a contribution for the Proceedings of 5th International Conference on New Frontiers in Physics (ICNFP 2016), held at Crete, 6-14 July 2016. Our goal is to obtain phenomenologically reliable insights for the physics of the quark-gluon plasma (QGP) from the holography. I briefly review how in the holographic setup one can describe the QGP formation in heavy ion collisions and how to get quantitatively the main characteristics of the QGP formation -- the total multiplicity and the thermalization time. To fit the experimental form of dependence of total multiplicity on energy, obtained at …
The frequency dependent conductivity $σ(ω)$ of the strongly coupled Quark-Gluon Plasma (QGP) is estimated using a bottom up holographic model that can adequately describe recent lattice data for QCD thermodynamics at zero chemical potential. Different choices for the coupling between the bulk gauge field and the other bulk fields that define the background (the metric and a scalar field) are used in order to fit the lattice data for the electric charge susceptibility $χ_2^Q/T^2$. The ratio $σ_{DC}/T$ is found to vary near the deconfinement transition in a way that is similar to recent lattice …
The strongly-coupled phase of the quark-gluon plasma (QGP) is studied here by resorting to a $T$-matrix formulation in which the medium is seen as a non-ideal gas of quasiparticles (quarks, antiquarks and gluons) interacting nonpertubatively. In the temperature range under study, (1-5) $T_c$, where $T_c$ is the temperature of deconfinement, the interactions are expected to be strong enough to generate bound states. The dissociation temperature of such binary bound states is thus computed here. The more the quasiparticles involved in the binary system are heavy, the more the bound state is like…
Using the grand canonical ensemble formulation of a multi-particle statistical system, the thermodynamical description of the dual QCD has been presented in terms of the bag model of hadrons and analyzed for the quark-gluon plasma phase of hadronic matter. The dual QCD bag construction has been shown to lead to the radial pressure on the bag surface in terms of the vector glueball masses of the magnetically condensed QCD vacuum. Constructing the grand canonical partition function to deal with the quark-gluon plasma phase of the non-strange hadrons, the energy density and the plasma pressure ha…
The deconfinement transition region between hadronic matter and quark-gluon plasma is studied for finite volumes. Assuming simple model equations of state and a first order phase transition, we find that fluctuations in finite volumes hinder a sharp separation between the two phases around the critical temperature, leading to a rounding of the phase transition. For reaction volumes expected in heavy ion experiments, the softening of the equation of state is reduced considerably. This is especially true when the requirement of exact color-singletness is included in the QGP equation of state.
We study the influence of the baryon chemical potential $μ_B$ on the properties of the Quark-Gluon-Plasma (QGP) in and out-of equilibrium. The description of the QGP in equilibrium is based on the effective propagators and couplings from the Dynamical QuasiParticle Model (DQPM) that is matched to reproduce the equation-of-state of the partonic system above the deconfinement temperature $T_c$ from lattice QCD. We study the transport coefficients such as the ratio of shear viscosity $η$ and bulk viscosity $ζ$ over entropy density $s$, i.e. $η/s$ and $ζ/s$ in the $(T,μ)$ plane and compare to othe…
We study the influence of the baryon chemical potential $μ_B$ on the properties of the Quark-Gluon-Plasma (QGP) in and out-of equilibrium. The description of the QGP in equilibrium is based on the effective propagators and couplings from the Dynamical QuasiParticle Model (DQPM) that is matched to reproduce the equation-of-state of the partonic system above the deconfinement temperature $T_c$ from lattice Quantum Chromodynamics (QCD). We calculate the transport coefficients such as the ratio of shear viscosity $η$ and bulk viscosity $ζ$ over entropy density $s$, i.e., $η/s$ and $ζ/s$ in the $(T…
Substantial anisotropies should occur in the hot expanding QCD plasma produced in relativistic heavy-ion collisions due to non-vanishing shear viscosity. We discuss the form of the real-time, hard thermal loop resummed propagator for static gluons in the presence of such anisotropies and the consequences for quarkonium binding. It has been predicted that the propagator develops an imaginary part due to Landau damping at high temperature. This generates a much larger width of quarkonium states than the Appelquist-Politzer vacuum estimate corresponding to decay into three gluons. We argue that t…
We study the dynamics of confinement-deconfinement (C-D) phase transition in the context of relativistic heavy-ion collisions within the framework of effective models for the Polyakov loop order parameter. We study the formation of $Z(3)$ walls and associated strings in the initial transition from the confining (hadronic) phase to the deconfining (QGP) phase via the so called Kibble mechanism. Essential physics of the Kibble mechanism is contained in a sort of domain structure arising after any phase transition which represents random variation of the order parameter at distances beyond the ty…
We study a phenomenological model that mimics the characteristics of QCD theory at finite temperature. The model involves fermions coupled with a modified Abelian gauge field in a tachyon matter. It reproduces some important QCD features such as, confinement, deconfinement, chiral symmetry and quark-gluon-plasma (QGP) phase transitions. The study may shed light on both light and heavy quark potentials and their string tensions. Flux-tube and Cornell potentials are developed depending on the regime under consideration. Other confining properties such as scalar glueball mass, gluon mass, gluebal…
After the discovery of the Quantum Chromodynamics (QCD), many experimental and theoretical efforts have been made to investigate physics issues involved in ultra relativistic heavy-ion collisions. The fundamental goal of this work is to present a short guide of the underlying theory of strong interactions with emphasis on the light vector mesons based on the exceptional work of R.Rapp and J.Wambach. Today widely believed that deconfinement and chiral symmetry restoration probably takes place in a hot and dense hadronic medium as this produced at these collisions. We focus at the place where th…
We present calculations for the shear viscosity of the hot and dense quark-gluon plasma (QGP) using the partonic scattering cross sections as a function of temperature $T$ and baryon chemical potential $μ_B$ from the dynamical quasiparticle model (DQPM) that is matched to reproduce the equation of state of the partonic system above the deconfinement temperature $T_c$ from lattice QCD. To this aim we calculate the collisional widths for the partonic degrees of freedom at finite $T$ and $μ_B$ in the time-like sector and conclude that the quasiparticle limit holds sufficiently well. Furthermore, …
A beam energy scan has been carried out at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory to search for the onset of deconfinement and a possible critical point where the transition from a Quark Gluon Plasma to a hadronic phase changes from a rapid cross-over to a first order phase transition. Anisotropy in the azimuthal distribution of produced particles such as the second and third harmonics $v_2$ and $v_3$ are expected to be sensitive to the existence of a Quark Gluon Plasma phase and the Equation of State of the system. For this reason, they are of great experimental…
We utilize a new framework, CUJET3.0, to deduce the energy and temperature dependence of jet transport parameter, $\hat{q}(E>10\; {\rm GeV},T)$, from a combined analysis of available data on nuclear modification factor and azimuthal asymmetries from RHIC/BNL and LHC/CERN on high energy nuclear collisions. Extending a previous perturbative-QCD based jet energy loss model (known as CUJET2.0) with (2+1)D viscous hydrodynamic bulk evolution, this new framework includes three novel features of nonperturbative physics origin: (1) the Polyakov loop suppression of color-electric scattering (aka "semi-…
