On parton number fluctuations at various stages of the rapidity evolution

Starting with the interpretation of parton evolution with rapidity as a branching-diffusion process, we describe the different kinds of fluctuations of the density of partons which affect the properties of QCD scattering amplitudes at moderately high energies. We then derive some of these properties as direct consequences of the stochastic picture. We get new results on the expression of the saturation scale of a large nucleus, and a modified geometric scaling valid at intermediate rapidities for dipole-dipole scattering.Comment: 18 pages, 3 figures. v2: Improved writing; In particular, extended discussion of the dipole-dipole case in Sec. 4. A few misprints corrected. To appear in Phys. Lett.

Studying pion effects on the chiral phase transition

We investigate the chiral phase transition at finite temperatures and zero chemical potential with Dyson-Schwinger equations. Our truncation for the quark-gluon interaction includes mesonic degrees of freedom, which allows us to study the impact of the pions on the nature of the phase transition. Within the present scheme we find a five percent change of the critical temperature due to the pion backreaction whereas the mean field character of the transition is not changed.Comment: 2 pages, 2 figures, talk given by J.A.M. at the 30th International School of Nuclear Physics, Erice, Sicily from 16 - 24 September 200

On critical scaling at the QCD N_f=2 chiral phase transition

We investigate the critical scaling of the quark propagator of N_f=2 QCD close to the chiral phase transition at finite temperature. We argue that it is mandatory to take into account the back-reaction effects of pions and the sigma onto the quark to observe critical behavior beyond mean field. On condition of self-consistency of the quark Dyson-Schwinger equation we extract the scaling behavior for the quark propagator analytically. Crucial in this respect is the correct pion dispersion relation when the critical temperature is approached from below. Our results are consistent with the known relations for the quark condensate and the pion decay constant from universality. We verify the analytical findings also numerically assuming the critical dispersion relation for the Goldstone bosons.Comment: 9 pages, 6 figure

A Modified "Bottom-up" Thermalization in Heavy Ion Collisions

In the initial stage of the bottom-up picture of thermalization in heavy ion collisions, the gluon distribution is highly anisotropic which can give rise to plasma instability. This has not been taken account in the original paper. It is shown that in the presence of instability there are scaling solutions, which depend on one parameter, that match smoothly onto the late stage of bottom-up when thermalization takes place.Comment: 8 pages and 1 embedded figure, talk presented at the Workshop on "Quark-Gluon Plasma Thermalization", Vienna, Austria, 10-12 August 200