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Showing papers on "Color-glass condensate published in 2003"


Book ChapterDOI
24 Mar 2003
TL;DR: The Color Glass Condensate (CGC) as mentioned in this paper was proposed to describe the behavior of the small x components of the hadronic wave function in QCD, and the Green functions of the theory satisfy Wilsonian renormalization group equations which reduce to standard linear QCD evolution equations in the limit of low parton densities.
Abstract: At very high energies or small values of Bjorken x, the density of partons, per unit transverse area, in hadronic wavefunctions becomes very large leading to a saturation of partonic distributions. When the scale corresponding to the density per unit transverse area, the saturation scale Q_s, becomes large (Q_s\gg \Lambda_{QCD}), the coupling constant becomes weak (\alpha_S(Q_s)\ll 1) which suggests that the high energy limit of QCD may be studied using weak coupling techniques. This simple idea can be formalized in an effective theory, the Color Glass Condensate (CGC), which describes the behavior of the small x components of the hadronic wavefunction in QCD. The Green functions of the theory satisfy Wilsonian renormalization group equations which reduce to the standard linear QCD evolution equations in the limit of low parton densities. The effective theory has a rich structure that has been explored using analytical and numerical techniques. The CGC can be applied to study a wide range of high energy scattering experiments from Deep Inelastic Scattering at HERA and the proposed Electron Ion Collider (EIC) to proton/deuterium-nucleus and nucleus-nucleus experiments at the RHIC and LHC colliders.

462 citations


Journal ArticleDOI
TL;DR: In this article, the predictions of the theory of a color glass condensate for a gluon production cross section in $p(d)A$ collisions are reviewed. But they do not consider the effect of quantum evolution at higher energies or rapidities.
Abstract: We review the predictions of the theory of a color glass condensate for a gluon production cross section in $p(d)A$ collisions. We demonstrate that, at moderate energies, when the gluon production cross section can be calculated in the framework of the McLerran-Venugopalan model, it has only a partonic level Cronin effect in it. At higher energies or rapidities corresponding to smaller values of the Bjorken x, quantum evolution becomes important. The effect of quantum evolution at higher energies or rapidities is to introduce the suppression of high-${p}_{T}$ gluons slightly decreasing the Cronin enhancement. At still higher energies or rapidities quantum evolution leads to the suppression of produced gluons at all values of ${p}_{T}.$

305 citations


Journal ArticleDOI
TL;DR: In this article, it was shown that the suppression of high p t hadrons discovered recently in heavy ion collisions at RHIC may be a consequence of saturation in the color glass condensate.

249 citations


Journal ArticleDOI
TL;DR: A broad overview of the theoretical status and phenomenological applications of the color glass condensate effective field theory can be found in this article, which describes universal properties of saturated gluons in hadron wave functions that are extracted from deep-inelastic scattering and hadron-hadron collisions at high energies.

221 citations


Journal ArticleDOI
TL;DR: In this paper, the authors extend previous work on high energy nuclear collisions in the Color Glass Condensate model to study collisions of finite ultrarelativistic nuclei, and show that the gluon distribution in the nuclear wavefunction before the collision is significantly suppressed below the saturation scale when compared to the simple McLerran-Venugopalan model prediction, while the behavior at large momentum p T ⪢ Λ s remains unchanged.

125 citations


Book ChapterDOI
TL;DR: The Color Glass Condensate (CGC) as mentioned in this paper was proposed to describe the behavior of the small x components of the hadronic wave function in QCD, and the Green functions of the theory satisfy Wilsonian renormalization group equations which reduce to standard linear QCD evolution equations in the limit of low parton densities.
Abstract: At very high energies or small values of Bjorken x, the density of partons, per unit transverse area, in hadronic wavefunctions becomes very large leading to a saturation of partonic distributions. When the scale corresponding to the density per unit transverse area, the saturation scale Q_s, becomes large (Q_s\gg \Lambda_{QCD}), the coupling constant becomes weak (\alpha_S(Q_s)\ll 1) which suggests that the high energy limit of QCD may be studied using weak coupling techniques. This simple idea can be formalized in an effective theory, the Color Glass Condensate (CGC), which describes the behavior of the small x components of the hadronic wavefunction in QCD. The Green functions of the theory satisfy Wilsonian renormalization group equations which reduce to the standard linear QCD evolution equations in the limit of low parton densities. The effective theory has a rich structure that has been explored using analytical and numerical techniques. The CGC can be applied to study a wide range of high energy scattering experiments from Deep Inelastic Scattering at HERA and the proposed Electron Ion Collider (EIC) to proton/deuterium-nucleus and nucleus-nucleus experiments at the RHIC and LHC colliders.

118 citations


Journal ArticleDOI
TL;DR: In this paper, it was shown that particle production in proton-nucleus (pA) collisions in the color glass condensate model can be related to deep inelastic scattering (DIS) of leptons on protons or nuclei.
Abstract: We show that particle production in proton-nucleus (pA) collisions in the color glass condensate model can be related to deep inelastic scattering (DIS) of leptons on protons or nuclei. The common building block is the quark-antiquark (or gluon-gluon) dipole cross section which is present in both DIS and pA processes. This correspondence in a sense generalizes the standard leading twist approach to pA collisions based on collinear factorization and perturbative QCD, and allows one to express the pA cross sections in terms of a universal quantity (dipole cross section) which, in principle, can be measured in DIS or other processes. Therefore, using the parametrization of the dipole cross section at DESY HERA, one can calculate particle production cross sections in proton-nucleus collisions at high energies. Alternatively, one could use proton-nucleus experiments to further constrain models of the dipole cross section. We show that the McLerran-Venugopalan model predicts an enhancement of the cross sections at large ${p}_{\ensuremath{\perp}}$ (Cronin effect) and a suppression of the cross sections at low ${p}_{\ensuremath{\perp}}.$ The crossover depends on rapidity and moves to higher ${p}_{\ensuremath{\perp}}$ as one goes to more forward rapidities.

79 citations


Journal ArticleDOI
TL;DR: In this article, a Gaussian approximation to the effective theory for the color glass condensate was constructed, which describes correctly the gluon distribution both in the low density regime at high transverse momenta (above the saturation scale Q s ), and in the high density regime below Q s, and provides a simple interpolation between these two regimes.

77 citations


Journal ArticleDOI
TL;DR: In this paper, the numerical solution of the classical SU(3) Yang-Mills equations of motion in the McLerran-Venugopalan model for gluon production in central heavy ion collisions leads to a suppression at low p t and an enhancement at the intermediate p t region as compared to peripheral heavy ion and pp collisions at the same energy.

72 citations


Journal ArticleDOI
TL;DR: In this article, a semi-classical approach to the solution of non-linear evolution equation is developed, and the solution in the entire kinematic region to the non linear evolution equation that governs the dynamics in the high parton density QCD is found.

36 citations


Journal ArticleDOI
TL;DR: The relationship between RHIC and HERA data is explored using the idea of saturation (color glass condensate) as a unifying framework for interpretation in this article, where a description of the early stages of a heavy ion collision is given consistent with the RHIC results.

Journal ArticleDOI
TL;DR: In this article, the photonuclear production of heavy quarks in ultra-peripheral heavy ion collisions is calculated using sound high energy QCD formalisms like the collinear and semihard approaches as well as the saturation model.
Abstract: We calculate the photonuclear production of heavy quarks in ultraperipheral heavy ion collisions. The integrated cross section and the rapidity distribution are computed employing sound high energy QCD formalisms like the collinear and semihard approaches as well as the saturation model. In particular, the color glass condensate (CGC) formalism is also considered using a simple phenomenological parameterization for the color field correlator in the medium, which allows us to obtain more reliable estimates for charm and bottom production at LHC energies.

Journal ArticleDOI
TL;DR: In this article, the phase coherence between sites along the lattice as well as the radial profile of the condensate after a time-of flight was analyzed, and a simple model was proposed that predicts the short-time dephasing as a function of the Condensate parameters.
Abstract: The dynamics of a Bose-Einstein condensate nonadiabatically loaded into a one-dimensional optical lattice is studied by analyzing the phase coherence between sites along the lattice as well as the radial profile of the condensate after a time-of flight. A simple model is proposed that predicts the short-time dephasing as a function of the condensate parameters. In the radial direction, heavily damped oscillations are observed, as well as an increase in the condensate temperature. These findings are interpreted as a rethermalization due to dissipation of the initial condensate excitations into high-lying modes.

Posted Content
TL;DR: In this article, the authors provide an introduction to the physics issues which are being studied in the RHIC heavy ion program, which center around the production of new states of matter.
Abstract: The purpose of these lectures is to provide an introduction to the physics issues which are being studied in the RHIC heavy ion program. These center around the production of new states of matter. The Quark Gluon Plasma is thermal matter which once existed in the big bang which may be made at RHIC. The Color Glass Condensate is a universal form of matter which controls the high energy limit of strong interactions. Both such forms of matter might be produced and probed at RHIC.

Journal ArticleDOI
TL;DR: In this paper, the photonuclear production of heavy quarks in ultra-peripheral heavy ion collisions is calculated using sound high energy QCD formalisms such as the collinear and semihard approaches as well as the saturation model.
Abstract: We calculate the photonuclear production of heavy quarks in ultraperipheral heavy ion collisions. The integrated cross section and the rapidity distribution are computed employing sound high energy QCD formalisms as the collinear and semihard approaches as well as the saturation model. In particular, the color glass condensate (CGC) formalism is also considered using a simple phenomenological parameterization for the color field correlator in the medium, which allow us to obtain more reliable estimates for charm and bottom production at LHC energies.

Journal ArticleDOI
TL;DR: In this paper, a novel mechanism for jet quenching in heavy ion collisions was proposed, whereby high-p + t partons get depleted through strong (classical) color fields.
Abstract: We consider synchrotronlike radiation in QCD by generalizing Schwinger's treatment of quantum synchrotron radiation in QED to the case of a constant chromomagnetic field. We suggest a novel mechanism for jet quenching in heavy ion collisions, whereby high-${p}_{t}$ partons get depleted through strong (classical) color fields. The latter are encountered in the color glass condensate or in the form of expanding shells of exploding sphalerons. Unlike bremsstrahlung radiation through multiple soft rescattering, synchrotron radiation converts a jet into a wide shower of soft gluons. We estimate the energy loss through this mechanism and suggest that it contributes significantly to the unexpectedly strong jet quenching observed at BNL RHIC.

Journal ArticleDOI
TL;DR: In this paper, the authors derived non-perturbative expressions relating the distributions of produced partons to those of wee partons in the wavefunctions of the colliding nuclei.
Abstract: At very high energies, the partons in the nuclear wavefunction form a color glass condensate. Since the occupation number of partons in the color glass condensate is large, classical methods can be used to compute multi-particle production in the initial instants of a high energy heavy ion collision. Non-perturbative expressions are derived relating the distributions of produced partons to those of wee partons in the wavefunctions of the colliding nuclei. The time evolution of components of the stress‐energy tensor is studied and the impact parameter dependence of elliptic flow is extracted. We discuss the space-time picture that emerges and interpret the RHIC data within this framework.

Journal ArticleDOI
TL;DR: In this paper, the authors studied the coherent dissociation of a molecular condensate into a multiple-mode atomic Condensate during the chemical potential curve crossing beyond the mean-field approximation.
Abstract: In this paper, we study the coherent dissociation of a molecular condensate into a multiple-mode atomic condensate during the chemical-potential curve crossing beyond the mean-field approximation. We show that the problem can be reduced to the dissociation of a molecular condensate into a two-mode atomic one. We employ the time-dependent Landau-Zener theory and derive analytical expression for the transition amplitudes. We calculate the number of produced atoms and show that they exist in squeezed state. We also study the formation of multiple-mode atomic condensate by inelastic scatterings of atoms in a single-mode atomic condensate. We show that the problem is also a Landau-Zener-like and exact solution can be found by imposing an additional symmetry.

Journal ArticleDOI
TL;DR: In this article, the authors provide an introduction to the physics issues which are being studied in the RHIC heavy ion program, which center around the production of new states of matter.
Abstract: The purpose of these lectures is to provide an introduction to the physics issues which are being studied in the RHIC heavy ion program. These center around the production of new states of matter. The quark gluon plasma is thermal matter which once existed in the big bang which may be made at RHIC. The color glass condensate is a universal form of matter which controls the high energy limit of strong interactions. Both such forms of matter might be produced and probed at RHIC.

Journal ArticleDOI
TL;DR: In this article, the color glass condensate (CGC) theory was used to explain the geometric scaling phenomenon observed in deep inelastic scattering at small χ, where the total γ ∗ p cross section depends upon the two variables Q2 and χ only via their combination ζ ≡ Q2R02(χ), with R02χ ∞ χλ.

01 Jan 2003
TL;DR: In this article, the authors provide an introduction to the physics issues which are being studied in the RHIC heavy ion program, which center around the production of new states of matter.
Abstract: The purpose of these lectures is to provide an introduction to the physics issues which are being studied in the RHIC heavy ion program. These center around the production of new states of matter. The Quark Gluon Plasma is thermal matter which once existed in the big bang which may be made at RHIC. The Color Glass Condensate is a universal form of matter which controls the high energy limit of strong interactions. Both such forms of matter might be produced and probed at RHIC.

Journal ArticleDOI
TL;DR: In this article, it was shown that an observable fraction of the measured elliptic flow may originate in classical gluon fields at the initial stage of a peripheral high-energy nuclear collision.

Journal ArticleDOI
TL;DR: The Color Glass Condensate may be formed in these collisions as discussed by the authors, and the recent results from RHIC are discussed in this context, as well as other results from the RHIC experimental program at Brookhaven National Laboratory.
Abstract: The central goal of the RHIC experimental program at Brookhaven National Laboratory is to make and study the Quark Gluon Plasma. Another new form of matter, the Color Glass Condensate may be formed in these collisions. The recent results from RHIC are discussed in this context.

Journal ArticleDOI
TL;DR: In this paper, the authors review recent applications of the classical Yang-Mills formalism to the dynamics in the central-rapidity region of high-energy heavy-ion collisions.
Abstract: I review recent applications of the classical Yang-Mills formalism to the dynamics in the central-rapidity region of high-energy heavy-ion collisions.

Posted Content
TL;DR: In this article, basic concepts of the effective theory for the color glass condensate which describes the high energy limit of QCD interactions are reviewed and a discussion of the relationship between color glass and QCD is presented.
Abstract: I review basic concepts of the effective theory for the color glass condensate which describes the high-energy limit of QCD interactions.