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Color-glass condensate

About: Color-glass condensate is a research topic. Over the lifetime, 885 publications have been published within this topic receiving 35169 citations.


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TL;DR: In this article, a stable ferromagnetic ground state of gluons with a single longitudinal momentum was found in a two-dimensional quantum well of dense quark matter, and it was shown that the stable ground state can be obtained by the Savvidy instability.
Abstract: Solving instability of Savvidy vacuum in QCD is a longstanding problem. Using light cone quantization we analyze the problem not in the real confining vacuum but in dense quark matter where gluons interact weakly with each other. We find a stable ferromagnetic ground state of gluons which carry a single longitudinal momentum. Their states are composed as if they are confined in a two dimensional quantum well. This supports our previous result that gluons form a quantum Hall state in dense quark matter. About 30 years ago, Savvidy[1] showed that a color magnetic field is generated spontaneously in the Yang-Mills gauge theory. Namely, when one calculates an effective potential of the color magnetic field using the one loop approximation, it is found that the nontrivial color magnetic field is generated spontaneously. But, soon after it has been shown[2] that some of gluons have imaginary energies under the color magnetic field and produce an imaginary part in the effective potential. The existence of the nontrivial imaginary part in the effective potential implies the instability of the vacuum with the color magnetic field. Some of gluons are unstable in the vacuum. We call it as Savvidy instability. This magnetic instability of the vacuum in the Yang-Mills gauge theory was expected by many authors to lead to a confining vacuum. Namely, it was expected that the confining vacuum would be realized by the condensation of the unstable gluons. The subsequent analysis[3] of the gluons has revealed the complication of the color magnetic flux due to the production of additional magnetic field generated by the unstable gluons. Although the formation of a lattice of the flux tube has been argued[3], any other clear pictures of such complicate states formed by the unstable gluons have not been presented. Eventually, a confining vacuum could not be obtained. We have recently investigated the Savvidy instability in dense quark matter and shown[4] that the instability is solved by the formation of a stable quantum Hall state[5, 6] of the unstable gluons. Since perturbative arguments such as loop expansions are applicable in sufficiently dense quarkmatter, it is reliable that the spontaneous generation of the color magnetic field arises in the matter. Although the quantum Hall states is realized nonperturbatively due to the effect of gluon’s repulsive self interactions, this formation mechanism is well established in the physics of quantum Hall states of electrons. This is similar to the formation mechanism of BCS states; BCS states arise due to the effect of attractive forces between electrons on the Fermi surface, even if the forces are fairly weak. Hence, it is also reliable that the quantum Hall states of the gluons arise in the dense quark matter. Consequently, we may understand that Savvidy instability is solved in the dense quark matter. It is composed of quarks, the color magnetic field and the colored quantum Hall state of gluons. The phase of the quark matter is called as color ferromagnetic phase. Although quarks occupy Landau levels, they do not form quantum Hall states in general. ( We have shown[4] that the color ferromagnetic phase is realized in the quark matter with lower densities than ones with which color superconductivity[7] is realized. Thus, the phase is phenomenologically more important than the color superconducting phase. We have discussed an astrophysical implication of the phase[8] and also have pointed out the similarity[9] between the gluons in the dense quark matter and color glass condensate in nucleons. ) Quantum Hall states arise only in two dimensional space. For example, quantum Hall states of electrons are realized in quantum wells of semiconductors, which are effectively two dimensional. Excitations with nontrivial momenta perpendicular to the two dimensional well are forbidden energetically as far as we are concerned with smaller energies ( or lower temperature ) than a finite gap. Thus, only excitations with smaller energies than the gap are allowed and they are excitations in the two dimensional well. This is a feature of the two dimensional quantum well. Then, it is natural to ask how two dimensional quantum Hall states of gluons are formed in the three dimensional dense quark matter. In this paper we analyze the problem as well as Savvidy instability, using the light cone quantization[10, 11]. Since QCD Hamiltonian with color magnetic field can be well defined in the quantization, it is easy to analyze ground states of the gluons with the use of an approximation valid at small couplings. As a result we find that the gluons in the lowest Landau level form a ground state in which all of the gluons have a single longitudinal momentum. Furthermore, the energies of excitations with the same longitudinal momentum as the momentum of the gluons in the ground state, are much smaller than the energies of excitations with nontrivial longitudinal momenta. Such excitations arise in the two dimensional transverse space. Thus, the gluons are two dimensional since their excitations are only allowed in the transverse directions as far as we are concerned with much small energies. In this way two dimensional gluonic states arise effectively in the three dimensional quark matter. All of them carry the single longitudinal momentum. These gluons may form quantum Hall states, but we do not discuss in this paper how the two dimensional gluons
Journal ArticleDOI
TL;DR: In this paper, the authors discuss recent theoretical work about AA collisions at RHIC energies, largely from our group at BNL and the group at the RIKEN-BNL Center.
Abstract: I discuss recent theoretical work about AA collisions at RHIC energies, largely from our group at BNL and the group at the RIKEN-BNL Center. Most of the discussion is about the impact of the Color Glass Condensate on the production and evolution of matter in heavy ion collisions.
Journal ArticleDOI
TL;DR: In this paper, the authors discuss azimuthal correlations in dAu collisions at different rapidities and centralities and argue that experimentally observed depletion of the back-to-back correlation peak can be quantitatively explained by gluon saturation in the Color Glass Condensate of the gold nucleus.
01 May 2010
TL;DR: In this article, the authors present a review of the recent phenomenological analyses of RHIC data based on the Color Glass Condensate, including the use of non-linear evolution equations with running coupling.
Abstract: I present a brief review of the recent phenomenological analyses of RHIC data based on the the Color Glass Condensate, including the use of non-linear evolution equations with running coupling. In particular, I focus in the study of the total multiplicities in Au+Au collisions, and in the single inclusive and double inclusive forward spectra in d+Au collisions. Predictions for the LHC are also discussed

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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202321
202244
202127
202022
201951
201833