arXiv subjects
Publications and source records attributed to Larry McLerran.
At high baryon number density, it has been proposed that a new phase of QCD matter controls the physics. This matter is confining but can have densities much larger than $Λ^3_{QCD}$ QCD. Its existence is argued from large Nc approximations, and model computations. It is approximately chirally symmetric.
The large Nc limit provides a good phenomenology of meson spectra and interactions. I discuss some problems with applying the large Nc approximation to the description of baryons, and point out a number of apparent paradoxes and phenomenological difficulties.
Relativistic Heavy Ion Collider experiments exhibit correlations peaked in relative azimuthal angle and extended in rapidity. Called the ridge, this peak occurs both with and without a jet trigger. We argue that the untriggered ridge arises when particles formed by flux tubes in an early glasma stage later manifest transverse flow. Combining a blast wave model of flow fixed by single-particle spectra with a simple description of the glasma, we find excellent agreement with current data.
I provide a brief introduction to the theoretical ideas and phenomenological motivation for the Color Glass Condensate and the Glasma
I discuss the ridge phenomena observed in heavy ion collisions at RHIC. I argue that the ridge may be due to flux tubes formed from the Color Glass Condensate in the early Glasma phase of matter produced in such collisions
This lecture concerns the properties of strongly interacting matter (which is described by Quantum Chromodynamics) at very high energy density. I review the properties of matter at high temperature, discussing the deconfinement phase transition . At high baryon density and low temperature, large $N_c$ arguments are developed which suggest that high baryonic density matter is a third form of matter, Quarkyonic Matter, that is distinct from confined hadronic matter and deconfined matter. I finally discuss the Color Glass Condensate which controls the high energy limit of QCD, and forms the low x part of a hadron wavefunction. The Glasma is introduced as matter formed by the Color Glass Condensate which eventually thermalizes into a Quark Gluon Plasma.
Quarkyonic matter is a new phase of QCD at finite temperature and density which is distinct from the confined and de-confined phases. Its existence is unambiguously argued in the large number of colors limit in QCD. Hints of its existence for 3 color QCD are shown in lattice Monte-Carlo data and heavy ion experiments.
The high energy limit of QCD is controlled by very high energy density gluonic matter, the Color Glass Condensate. In the first instants of the collisions of two sheets of Colored Glass Condensate, a Glasma is formed with longitudinal flux tubes of color electric and magnetic fields. These flux tubes decay and might form a turbulent liquid that eventually thermalizes into a Quark Gluon Plasma
I review the history of the efforts using heavy ion collisions to make new forms of matter. I discuss both the development of the theoretical ideas about such new forms of matter, as well the past, present and planned experimental efforts. I also highlight the development of this activity in both India and China.
We investigate the consequences of long range rapidity correlations in the Glasma. Particles produced locally in the transverse plane are correlated by approximately boost invariant flux tubes of longitudinal color electric and magnetic fields that are formed when two sheets of Colored Glass Condensate pass through one another, each acquiring a modified color charge density in the collision. We argue that such long range rapidity correlations persist during the evolution of the Quark Gluon Plasma formed later in the collision. When combined with transverse flow, these correlations reproduce many of the features of the recently observed ridge events in heavy ion collisions at RHIC.
These two lectures concern the Color Glass Condensate and the Glasma. These are forms of matter which might be studied in high energy hadronic collisions. The Color Glass Condensate is high energy density gluonic matter. It constitutes the part of a hadron wavefunction important for high energy processes. The Glasma is matter produced from the collision of two high energy hadrons. Both types of matter are associated with coherent fields. The Color Glass Condensate is static and related to a hadron wavefunction where the glasma is transient and evolves quickly after a collision. I present the properties of such matter, and some aspects of what is known of their properties.
I discuss forms of high energy density matter in QCD. These include the Color Glass Condensate, the Glasma and the Quark Gluon Plasma. They all might be studied in ultra-relativistic heavy ion collisions, nd the Color Glass Condensate might also be probed in electron-hadron collisions. I present the properties of such matter and some aspects of what is known of their properties.
In the limit of a large number of colors, N_c, we suggest that gauge theories can exhibit several distinct phases at nonzero temperature and quark density. Two are familiar: a cold, dilute phase of confined hadrons, where the pressure is ~ 1, and a hot phase of deconfined quarks and gluons, with pressure ~ N_c^2. When the quark chemical potential mu ~ 1, the deconfining transition temperature, T_d, is independent of mu. For T < T_d, as mu increases above the mass threshold, baryons quickly form a dense phase where the pressure is ~ N_c. As illustrated by a Skyrme crystal, chiral symmetry can be both spontaneously broken, and then restored, in the dense phase. While the pressure is ~ N_c, like that of (non-ideal) quarks, the dense phase is still confined, with interactions near the Fermi surface those of baryons, and not of quarks. Thus in the chirally symmetric region, baryons near the Fermi surface are parity doubled. We suggest possible implications for the phase diagram of QCD.
I argue that the physics of the scattering of very high energy strongly interacting particles is controlled by a new, universal form of matter, the Color Glass Condensate. This matter is the dominant contribution to the low x part of a hadron wavefunction. In collisions, this matter almost instantaneously turns into a Glasma. The Glasma initially has strong longitudinal color electric and magnetic fields, with topological charge. These fields melt into gluons. Due to instabilities, quantum noise is converted into classical turbulence, which may be responsible for the early thermalization seen in heavy ion collisions at RHIC.
I give an overview of the presentations at the International Symposium on Multiparticle Dynamics
We argue that quantum Liouville field theory supplemented with a suitable source term is the effective theory which describes the short-range correlations of the gluon saturation momentum in the two-dimensional impact-parameter space, at sufficiently high energy and for a large number of colors. This is motivated by recent developments concerning the stochastic aspects of the high-energy evolution in QCD, together with the manifest scale invariance of the respective evolution equations and general considerations on the uncertainty principle. The source term explicitly breaks down the conformal symmetry of the (pure) Liouville action, thus introducing a physical mass scale in the problem which is identified with the average saturation momentum. We construct this source term for the case of a homogeneous distribution and show that this leads to an interesting theory: the relevant correlation functions are ultraviolet finite (and not just renormalizable) when computed in perturbation theory, due to mutual cancellations of the tadpole divergences. Possible generalizations to inhomogeneous source terms are briefly discussed.
I report on recent theoretical developments at Quark Matter 2006.
The Color Glass Condensate (CGC) predicts the form of the nuclear wavefunction in QCD at very small x. Using this, we compute the wavefunction for the collision of two nuclei, infinitesimally in the forward light cone. We show that the Wigner transformation of this wavefunction generates rapidity dependent fluctuations around the boost invariant classical solution which describe the Glasma in the forward light cone.