The glasma initial state and JIMWLK factorization

We review recent work on understanding the next to leading order corrections to the classical fields that dominate the initial stages of a heavy ion collision. We have recently shown that the leading ln(1/x) divergences of these corrections to gluon multiplicities can be factorized into the JIMWLK evolution of the color charge density distributions.Comment: 4 pages, 2 figures. Talk given by T.L. at Strong and Electroweak Matter 2008 (SEWM08), August 26-29, 2008, Amsterdam, The Netherland

Quark-antiquark production from classical fields and chemical equilibration

We compute by numerical integration of the Dirac equation the number of quark-antiquark pairs produced in the classical color fields of colliding ultrarelativistic nuclei. The backreaction of the created pairs on the color fields is not taken into account. While the number of qqbar pairs is parametrically suppressed in the coupling constant, we find that in this classical field model it could even be compatible with the thermal ratio to the number of gluons. After isotropization one could thus have quark-gluon plasma in chemical equilibrium.Comment: 4 pages, 6 figures, contribution to proceedings of Quark Matter 2005, Budapest, Aug 4-

A new approach for the vertical part of the contour in thermal field theories

A lot of work has been devoted in the past to understand the role of vertical branch of the time path in thermal field theories, and in particular to see how to deal with it in the real-time formalism. Unlike what is commonly believed, I emphasize on the fact that the vertical part of the path contributes to real-time Green's functions, and I prove that this contribution is taken into account simply by the substitution $n(\omega_{\boldsymbol k})\to n(|k_o|)$ in the real time Feynman rules. This new proof is based on very simple algebraic properties of the contour integration.Comment: LaTeX2e, 2 postscript figures (requires the package graphics), 14 page

Photon production by a quark gluon plasma

In this talk, I review the status of the calculation of the photon production rate in a hot quark-gluon plasma. Particular emphasis is given to the discussion of the various length scales of the problem.Comment: Based on talks given at Quark Matter 2001, January 2001, Stony Brook, USA and at 36th Rencontres de Moriond, March 2001, Les Arcs, France (4 pages LaTeX document, 3 postscript figures

Long range rapidity correlations and the ridge in A+A collisions

We discuss results for n-gluon correlations that form the basis of the Glasma flux tube picture of early times in heavy ion collisions. Our formalism is valid to all orders in perturbation theory at leading logarithmic accuracy in x and includes both QCD bremsstrahlung and the many body screening and recombination effects that are important at large parton densities. Long range rapidity correlations, as seen in the near-side ridge in heavy ion collisions, are a chronometer of these early time strong color field dynamics. They also contain information on how radial flow develops in heavy ion collisions.Comment: 4 pages, 2 figures, Talk by R.V. at Quark Matter 2009, March 30-April 4 2009, Knoxville, TN, US

Kinetic theory of a longitudinally expanding system

We use kinetic theory in order to study the role of quantum fluctuations in the isotropization of the pressure tensor in a system subject to fast longitudinal expansion, such as the matter produced in the early stages of a heavy ion collision.Comment: Proceedings of the POETIC 6 conference. 7 figures, 7 page

Factorization in high energy nucleus-nucleus collisions

In this talk, we discuss the factorization of the logarithms of energy in the Color Glass Condensate framework.Comment: proceedings of the conference ISMD 2012, Kielce, Polan