We calculate the induced color charges Q_{ind.}^3, Q_{ind.}^8 and the effective vertex gamma - gamma - gluon generated in quark-gluon plasma with the A_0 condensate because of the color parity violation at this background. To imitate the case of heavy-ion collisions, we consider the model of the plasma confined in the narrow infinite plate and derive the classical gluon potentials Phi^3, Phi^8 produced by these charges. Two applications - scattering of photons on the plasma and conversion of gluon fields in two photons radiated from the plasma - are discussed.
We review free energy evolution of QGP (Quark-gluon plasma) under zero-loop, one loop and two loop corrections in the mean field potential. The free energies of QGP under the comparison of zero-loop and loop corrections of the interacting potential among the quarks, anti-quarks and gluons are shown. We observe that the formation of stable QGP droplet is dependent on the loop corrections with the different parametrization values of fluid. With the increase in the parametrization value, stability of droplet formation increases with smaller size of droplet. This indicates that the formation of QG…
We propose an algebraic form for the density of states of quarks and gluons in a Quark-Gluon Plasma (QGP) fireball in quasi-equilibrium with a hadronic medium as $ρ(k)= \frac α{k} + βk + δk^{2}$, and determine the parameters $α$, $β$ and $δ$ using Lattice Gauge results on the velocity of sound in QGP. The behaviour of the resulting $ρ(k)$ can be easily compared with the thermodynamic data on QGP that is expected from LHC and other RHIC experiments. Our numerical result shows a linear rise of the value of $ρ(k)$ for $k\sim T \approx 160 to 180 MeV$, which is significant, and throws light on the…
This M.Sc. thesis in Engineering Physics is an overview of the present theory of quark-gluon plasma (QGP) as well as an analysis of the stability criterion for possible stable cosmic QGP objects left over from the quark-hadron transition in the early Universe. It covers fundamental ideas of the formation and decay of the plasma, including the standard model, QCD, and the MIT bag model. I discuss the equation of state of a QGP and the possible signatures for a plasma created in heavy-ion collisions. Astrophysical aspects of QGP are put forward, including compact stars and the quark-hadron trans…
We propose that the reason for the non-ideal behavior seen in lattice simulation of quark gluon plasma (QGP) and relativistic heavy ion collisions (URHICs) experiments is that the QGP near T_c and above is strongly coupled plasma (SCP), i.e., strongly coupled quark gluon plasma (SCQGP). It is remarkable that the widely used equation of state (EoS) of SCP in QED (quantum electrodynamics) very nicely fits lattice results on all QGP systems, with proper modifications to include color degrees of freedom and running coupling constant. Results on pressure in pure gauge, 2-flavors and 3-flavors QGP, …
We have investigated the effect of viscosity on the gluonic dissociation of $J/ψ$ in an equilibrating plasma. Suppression of $J/ψ$ due to gluonic dissociation depend on the temperature and also on the chemical equilibration rate. In an equilibrating plasma, viscosity affects the temperature evolution and also the chemical equilibration rate, requiring both of them to evolve slowly compared to their ideal counter part. For Au+Au collisions at RHIC and LHC energies, gluonic dissociation of $J/ψ$ increases for a viscous plasma. Low $P_T$ $J/ψ$'s are found to be more suppressed due to viscosity th…
The effect of the non-extensive form of statistical mechanics proposed by Tsallis on the formation of a quark-gluon plasma (QGP) has been recently investigated in ref. \cite{1}. The results show that for small deviations ($\approx 10%$) from Boltzmann-Gibbs (BG) statistics in the QGP phase, the critical temperature for the formation of a QGP does not change substantially for a large variation of the chemical potential. In the present effort we use the extensive $κ$-deformed statistical mechanics constructed by Kaniadakis to represent the constituents of the QGP and compare the results with ref…
Based on the constituent quasiparticle model of the quark-gluon plasma (QGP), color quantum path-integral Monte-Carlo (PIMC) calculations of the thermodynamic properties of the QGP are performed. We extend our previous zero chemical potential simulations to the QGP at finite baryon chemical potential. The results indicate that color PIMC can be applied not only above the QCD critical temperature $T_c$ but also below $T_c$. Besides reproducing the lattice equation of state our approach yields also valuable additional insight into the internal structure of the QGP, via the pair distribution func…
Within the closed-time-path formalism of nonequilibrium QCD, we derive a Slavnov-Taylor (ST) identity for the gluon polarization tensor. The ST identity takes the same form both in Coulomb and covariant gauges. Application to quasi-uniform quark-gluon plasma (QGP) near equilibrium or nonequilibrium quasistationary QGP is made.
The historical context of the recent results from high energy heavy ion reactions devoted to the search of quark-gluon plasma (QGP) is reviewed, with emphasis on the surprises encountered. The evidence for QGP from heavy ion reactions is compared with that available from particle reactions.
We show that the dynamics of the Quark-Gluon Plasma is such that during hadronization the creation of hybrids will predominate over the creation of mesons, giving a novel signature of the existence of QGP. At T = 0 the $(q\bar{q}g)$ hybrids are known to decay strongly into a pair of mesons. We find that at temperatures relevant to the QGP, this channel is forbidden. This would lead to significant modifications of the photonic signals of the QGP.
Using an exactly solvable statistical model we discuss the equation of state of large/heavy and short-living quark gluon plasma (QGP) bags. We argue that the large width of the QGP bags explains not only the observed deficit in the number of hadronic resonances, but also clarifies the reason why the heavy QGP bags cannot be directly observed even as metastable states in a hadronic phase. Also the Regge trajectories of large and heavy QGP bags are established both in a vacuum and in a strongly interacting medium. It is shown that at high temperatures the average mass and width of the QGP bags b…
Here we address the question regarding the nature of quark gluon plasma (QGP), whether it is a liquid or strongly coupled plasma (SCP), using two different phenomenological models, namely quasi-particle model (qQGP) and strongly coupled quark gluon plasma (SCQGP). First we compare these two models, both of which explains the results of lattice simulation of quantum chromodynamics, as a function of plasma parameter and conclude that the QGP is largely ($T > 1.5 T_c$) SCQGP and only for $T < 1.5 T_c$ it may be a liquid.
Some aspects of heavy flavor probes of quark-gluon plasma (QGP) including quarkonia and open heavy flavor D- and B-mesons, aimed to study the properties of QGP, are discussed in this lecture note.
A calculation of the thermal quark propagator is presented taking the gluon condensate above the critical temperature into account. The quark dispersion relation following from this propagator is derived.
The relativistic heavy ion program developed at RHIC and now at LHC motivated a deeper study of the properties of the quark gluon plasma (QGP) and, in particular, the study of perturbations in this kind of plasma. We are interested on the time evolution of perturbations in the baryon and energy densities. If a localized pulse in baryon density could propagate throughout the QGP for long distances preserving its shape and without loosing localization, this could have interesting consequences for relativistic heavy ion physics and for astrophysics. A mathematical way to proove that this can happ…
The dynamics of Quark-gluon plasma (QGP) as a lump of deconfined free quarks and gluons is elaborated. Based on the first principal we construct the Lagrangian that represents the dynamics of QGP. To induce a hydrodynamics approach, we substitute the gluon fields with flow fields. As a result, the derived equation of Motion (E.O.M) for gluon dominated QGP shows the form that similar to Euler equation, and the energy momentum tensor also represents explicitly the system of ideal fluid. Combining the E.O.M and energy momentum tensor, the pressure and energy density distribution as the equation o…
The aim of this paper is to investigate the effect of a non-extensive form of statistical mechanics proposed by Tsallis on the formation of a quark-gluon plasma (QGP). We suggest to account for the effects of the dominant part of the {\itshape long-range} interactions among the constituents in the QGP by a change in the statistics of the system in this phase, and we study the relevance of this statistics for the phase transition. The results show that small deviations ($\approx 10%$) from Boltzmann-Gibbs statistics in the QGP produce a noticeable change in the phase diagram, which can, in prin…
We propose a simple statistical model for the density of states for quarks and gluons in a QGP droplet, making the Thomas-Fermi model of the atom and the Bethe-model for the nucleons as templates for constructing the density of states for the quarks and gluons with due modifications for the `hot' relativistic QGP state as against the `cold' non-relativistic atom and nucleons, which were the subject of the earlier `forebears' of the present proposal.We introduce `flow-parameters' $γ_{q,g}$ for the quarks and the gluons to take care of the hydrodynamical (plasma) flows in the QGP system as was d…
We discuss the energy variation of a parton passing through a quark-gluon plasma(QGP) taking into account nonlinear polarization effect. We find the parton can be accelerated by fluctuations in QGP, which gives us a new physical insight about the response of QGP to such external the current.
We investigate top anti-top quark pair production in lead-lead collisions at the Large Hadron Collider with nucleon-nucleon center of mass energy of 5.5 TeV. Due to the very high temperature and energy density created in heavy ion collision, a new state of QCD matter known as Quark-Gluon Plasma (QGP) is expected to be produced. Top decay products loose energy inside the QGP medium. Therefore, we also study the medium modifications of different kinematic distributions. We observe significant modification in the dijets and trijets invariant mass distributions.We also found that the peak position…
The strongly interacting matter under extreme conditions of temperature for the conjectured deconfined phase of the quark-gluon plasma is investigated. A systematic study of the form of the thermal ratio of the disorder deviation (TRDD) is presented with the emphasis on the degree of deviation of the TRDD-function from unity. The space-time evolution of quarks and gluons is studied in the framework of two-particle correlation functions to predict the space-time size of the closed deconfined phase.
On the basis of the semiclassical equations for quark-gluon plasma (QGP) and Yang-Mills equation, the generalized kinetic equation for waves with regard to its interaction is obtained. The physical mechanisms defining nonlinear scattering of a plasmon by QGP particles are analysed. The problem on a connection of nonlinear Landau damping rate of longitudinal oscillation with damping rate, obtained on the basis of hard thermal loops approximation, is considered.
Heavy quarks (charm and bottoms) are one of the few probes which are sensitive to the degrees of freedom of a Quark Gluon Plasma (QGP), which cannot be revealed by lattice gauge calculations in equilibrium. Due to the rapid expansion of the QGP energetic heavy quarks do not come to an equilibrium with the QGP. Their energy loss during the propagation through the QGP medium depends strongly on the modelling of the interaction of the heavy quarks with the QGP quarks and gluons, i.e. on the assuption of the degrees of freedom of the plasma. Here we compare the results of different models, the pQC…
Fluidity of quark-gluon plasma (QGP) is studied where interaction between quark and gluon is mapped through fugacity in particle distribution function using lattice quantum chromodynamics (LQCD) results.
The quasi-particle model of quark gluon plasma (QGP) is revisited here with thermodynamically consistent formalism, different from earlier studies, without the need of temperature dependent bag constant as well as other effects such as confinement effects, effective degrees of freedom etc. Our model has only one system dependent parameter and surpraisingly good fit to lattice results for gluon plasma, 2-flavor and 3-flavor QGP are obtained. The basic idea is to evaluate energy density $ε$ first from grand partition function of quasi-particle QGP and then derive all other thermodynamic function…
Charge fluctuations as a possible signal of quark - gluon plasma (QGP) were recently suggested. A short summary of comments presented on this subject is given and supplemented by a discussion of the coexistence of pions produced "directly" and through a QGP phase. Such a coexistence may obscure the expected plasma signal similarly to the effects considered in the comments mentioned above.
Several different transport processes, such as heat transport, momentum transport and charge transport, may take place at the same time in the quark-gluon plasma (QGP). The corresponding transport coefficients are heat conductivity, shear viscosity and electric conductivity respectively. In the present paper, we will study the color-electric conductivity of the QGP in presence of shear viscosity, which is focused on the connection between the charge transport and the momentum transport. To achieve that goal, we solve the viscous chromohydrodynamic equations which are obtained from the QGP kine…
We investigate whether the total number of electrons per collision, as a function of beam energy, is a potential quark-gluon-plasma (QGP) signature. At high beam energies, we find that, after experimental removal of the noise induced by Dalitz decays, the number of produced electrons is increased many times fold from the existence of the QGP. The robustness of the potential signal to differing theoretical assumptions makes it an attractive experimental parameter.
The possibility of unified description of hadron multiple production in heavy ion collisions over the wide energy interval, from few hundreds MeV/n at GSI/SIS through 11 GeV/n at BNL/AGS up to 160 GeV/n at CERN/SPS, has been emphasized recently by J. Cleymans and K. Redlich. They, and somewhat later B. Muller and J. Rafelski, treated this fact as an indication that quark-gluon plasma (QGP) can be produced even at very low energies of impinging nuclei. In our opinion, it rather witnesses that a massive constituent quark (valon) - not massless current quark and gluon! - is just what becomes "qui…
An abundance of the strangeness that can be induced in a thermalized quark-gluon plasma (QGP) is considered as a signal of the QGP phase appearing in the intermediate state of ultra-relativistic heavy-ion collisions. As a quantitative characteristic of this signal we take the ratio R_{K^+ K^-} = N_{K^+}/N_{K^-} of the multiplicities of the production of K^+_- mesons. This ratio is evaluated for a thermalized QGP phase of QCD and for the quark-gluon system escaped from the QGP phase. For a thermalized QGP phase the ratio R_{K^+ K^-} has been found as a smooth function of a 3-momentum of the K^+…
We consider the experimental ratios of multistrange to strange antibaryon production and compare them to the standard Quark-Gluon String Model predictions. The significant differences between the experimental bar(Xi)+/bar(Lambda) and, especially, bar(Omega)+/bar(Lambda) values and model predictions can be interpreted as the signal of the existence of an additional source of multistrange antibaryon production. The possible connection of this additional source with Quark-Gluon Plasma (QGP) formation can turn the bar(Omega)+ production into a good QGP signature.
Prospects of measuring polarized photons emitted from a quark-gluon plasma (QGP) are discussed. In particular, the detection of a possible quark spin polarization in a QGP using circularly polarized photons emitted from the plasma is studied. Photons leave the QGP without further interaction and thus provide a primary probe for quark polarization within the QGP. We find that photon polarization cannot solely arise due to a possible QGP momentum space anisotropy, but may be enhanced due to it. In particular, for oblate momentum distributions and high photon energies, quark polarization is effic…
A recent proposal to study charge fluctuations as a possible signal of quark-gluon plasma is discussed. It is shown that the "pion gas model" considered as the reference sample is unrealistic and the expected signal from plasma may be difficult to distinguish from that coming from "standard collisions".
Assuming that vector and scalar diquarks exist in the Quark-Gluon Plasma near the critical temporature $T_c$, baryons can be produced through the processes of quarks and diquarks forming $({1/2})^+$ baryon states. Ratios of different baryons can be estimated through this method, if such kind of QGP with diquarks can exists.
The effect of two loop correction in the formation of quark-gluon plasma (QGP) droplet is studied with the introduction of the two loop correction factor in the mean field potential. Due to the correction factor it shows stability in the droplet formation of QGP indicating at different parametrization factors of the QGP fluid. The correction factor in the potential also shows gluon parameter factor shifts to a larger value from its earlier value of gluon factor of one loop correction in obtaining the stable droplets. The results show decreasing in the observable QGP droplets and droplet sizes …
A fireball of QGP is evoluted at temperature dependent chemical potential by a statistical model in the pionic medium. We study the dilepton emission rate at temperature dependent chemical potential (TDCP) from such a fireball of QGP. In this model, we take the dynamical quark mass as a finite value dependence on temparature and parametrization factor of the QGP evolution. The temperature and factor in quark mass enhance in the growth of the droplets as well as in the dilepton emission rates. The emission rate from the plasma shows dilepton spectrum in the intermediate mass region (IMR) of (1.…
The different modifications of quark- and gluon-initiated jets in the quark-gluon plasma (QGP) produced in heavy-ion collisions is a long-standing question that has not yet received a definitive answer from experiments. In particular, the relative sizes of the modification of quark and gluon jets differ between theoretical models. Therefore, a fully data-driven technique is crucial for an unbiased extraction of the quark and gluon jet spectra and substructure. We perform a proof-of-concept study based on proton-proton and heavy-ion collision events from the \textsc{Pyquen} generator with stati…
This review of the Quantum Chromodynamics (QCD),the early universe Cosmoloical Phase Transition from the Quark-Gluon Plasma (QGP) to our present universe (QCDPT), Relativistic Heavy Ion Collisions (RHIC) which can produce the QGP, the possible detection of the QGP produced by the production of mixed hybrid heavy quark mesons. We also review recent studies of the production of mixed heavy quark hybrids via RHIC and heavy quark meson supression in p-Pb and Pb-Pb collisions.
In an absorptive plasma, damping of radiation mechanisms can influence the bremsstrahlung formation in case of large radiation formation lengths. We study qualitatively the influence of this effect on the gluon bremsstrahlung spectrum off heavy quarks in the quark-gluon plasma. Independent of the heavy-quark mass, the spectrum is found to be strongly suppressed in an intermediate gluon energy region which grows with increasing gluon damping rate and increasing energy of the heavy quark. Thus, just as polarization effects in the plasma render the bremsstrahlung spectra independent of the quark …
We study the effects of a finite chemical potential on the occurrence of cavitation in a quark gluon plasma (QGP). We solve the evolution equations of second order viscous relativistic hydrodynamics using three different equations of state. The first one was derived in lattice QCD and represents QGP at zero chemical potential. It was previously used in the study of cavitation. The second equation of state also comes from lattice QCD and is a recent parametrization of the QGP at finite chemical potential. The third one is similar to the MIT equation of state with chemical potential and includes…
Effect of quantum chromodynamics (QCD) interaction in quark-gluon plasma on electrical conductivity is studied, where lattice quantum chromodynamics (LQCD) results are mapped through quark and gluon degeneracy.
Based on an analogy with topologically ordered new state of matter in condensed matter systems, we propose a low energy effective field theory for a parity conserving liquid-like quark-gluon plasma (QGP) around critical temperature in quantum chromodynamics (QCD) system. It shows that below a QCD gap which is expected several times of the critical temperature, the QGP behaves like topological fluid. Many exotic phenomenon of QGP near the critical temperature discovered at RHIC are more readily understood by the suggestion that QGP is a topologically ordered state.
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…
Proton-nucleus collisions serve as an important baseline for the understanding and interpretation of the nucleus-nucleus collisions. These collisions have been employed to characterize the cold nuclear matter effects at SPS and RHIC energies for the past several years, as it was thought that Quark-Gluon Plasma (QGP) is not formed in such collisions. However, at the Large Hadron Collider (LHC), there seems a possibility that QGP is formed during proton-lead (p$-$Pb) collisions. In this work, we have derived an expression for gluon induced excitation of $J/ψ$ to $ψ(2S)$, using pNRQCD, and show t…
This is an introduction to the study of the in-medium behavior of quarkonia and its application to the quark-gluon plasma search in high energy nuclear collisions.
We describe the quark gluon plasma (QGP) as a thermalized quark-gluon system, the thermalized QGP phase of QCD. The hadronization of the thermalized QGP phase is given in a way resembling a coalescence model with correlated quarks and anti-quarks. The input parameters of the approach are the spatial volumes of the hadronization. We introduce three dimensionless parameters C_M, C_B and C_\bar{B} related to the spatial volumes of the production of low-lying mesons (M), baryons (B) and antibaryons (\bar{B}). We show that at the temperature T= 175 MeV our predictions for the ratios of multipliciti…
I discuss why photon production from the Quark Gluon Plasma (QGP) presents an interesting problem, both experimentally and theoretically. I show how the photon emission rate can be computed under the simplifying assumption that the QGP fully thermalizes. The theoretical issues are very similar to those for jet energy loss; so it should be possible to treat them in a common formalism and relate the predictions of one phenomenon to those of the other.
The formation probability of quark-gluon plasma in relativistic heavy ion collisions for colliding nuclei of different sizes is investigated in the framework of a bond percolation model. The results show that nuclei with sizes smaller than that of Pb or Au produce QGP with probability less than unity even at very high collision energies. The dependence of the QGP-formation probability on different nuclear sizes and on various centralities of Au-Au collision are presented.
I argue that a new form of matter is indeed seen in Pb+Pb collisions at CERN SPS. However, this Quark Matter (QM) is different from the theoretically predicted Quark Gluon Plasma (QGP) because its effective degrees of freedom seem to be the massive (dressed) constituent quarks instead of almost massless quarks and gluons. The equation of state of QM is hard,the time of its rehadronization is short, while the equation of state of a QGP is soft and the time of its rehadronization is long. Other similarities and differences are also summarized.
The formation of quark-gluon plasma (QGP) in relativistic heavy ion collision, is expected to be accompanied by a background of ordinary collision events without phase transition. In this short note an algorithm is proposed to select the QGP candidate events from the whole event sample. This algorithm is based on a simple geometrical consideration together with some ordinary QGP signal, e.g. the increasing of $K/π$ ratio. The efficiency of this algorithm in raising the 'signal/noise ratio' of QGP events in the selected sub-sample is shown explicitly by using Monte-Carlo simulation.
The thermodynamic properties of the quark gluon plasma($QGP$) as well as its phase diagram are calculated as a function of baryon density (chemical potential) and temperature. The $QGP$ is assumed to be composed of the light quarks only, i.e. the up and the down quarks, which interact weakly and the gluons which are treated as they are free. The interaction between quarks is considered in the framework of the one gluon exchange model which is obtained from the Fermi liquid picture. The bag model is used, with fixed bag pressure (${\cal B}$) for the nonperturbative part and the quantum chromody…
A recent letter published in the journal Nature reports observation at the relativistic heavy ion collider (RHIC) of quark-gluon plasma (QGP) formation in small asymmetric collision systems denoted as $p$-Au, $d$-Au and $^3$He-Au. The claimed phenomenon, described as `short-lived QGP droplets,' is inferred from a combination of Glauber Monte Carlo simulations, measurement of two azimuth Fourier amplitudes $v_2$ and $v_3$ and hydro theory calculations. While that claim follows a trend in recent years to report `signals' conventionally attributed to QGP as appearing also in smaller collision sys…
We discuss an outside-inside scenario for a first order quark-hadron transition in the Quark-Gluon Plasma (QGP) expected to be produced in heavy ion collisions, wherein the entire QGP region itself becomes like a subcritical bubble, and starts shrinking. We argue that this shrinking QGP bubble will lead to concentration of baryon number in a narrow beam like region in center, which can be detected by HBT analysis, or as a raised plateau in the rapidity plot of baryon number.
We use simple entropy arguments to estimate the possible size of the QGP at the AGS and the SPS. We find that the possibility to form a large volume of QGP at the AGS or the SPS is very small. The size of the QGP at RHIC and the LHC is also predicted.
While it is commonly believed that there is a {\it direct} transition from the hadronic to a quark gluon phase at high temperature, it would be prejudicial to rule out a sequence of dynamically generated intermediate scales. Using as guide, an effective lagrangian with unconfined gluons and constituent quarks, interacting with a chiral multiplet, we examine a scenario in which the system undergoes first-order transitions at $ T_{comp}$, the compositeness scale of the pions, at $T_χ$, the scale for spontaneous chiral symmetry breaking, and at $T_c$, the confinement temperature. We find that at …
