François Gélis

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In this note, we discuss the derivation of a formula that has been used in the literature in order to compute the number of photons emitted by a hot or dense system during a finite time. Our derivation is based on a variation of the standard operator-based S-matrix approach. The shortcomings of this formula are then emphasized, which leads to a negative(More)
two static quarks as a function of the distance between them. The solid line is the zero temperature potential, that shows a linear rise at large distance a sign of quark confinement. The dotted lines show the same potential at increasing temperatures. The main feature is that, while the short distance behavior is not much affected, the linearly increasing(More)
We develop a formalism for particle production in a field theory coupled to a strong time-dependent external source. An example of such a theory is the Color Glass Condensate. We derive a formula, in terms of cut vacuum-vacuum Feynman graphs, for the probability of producing a given number of particles. This formula is valid to all orders in the coupling(More)
The early stages of high energy heavy ion collisions are studied in the color glass condensate framework, with a real-time classical lattice simulation. When increasing the coupling constant, we observe a rapid increase of the ratio of longitudinal to transverse pressure. The transient regime that precedes this behavior is of the order of 1 fm/c.