V. K. Magas

Conditions for confinement and freeze-out

Abstract.Matter implies the existence of a large-scale connected cluster of a uniform nature. The appearance of such clusters as a function of hadron density is specified by percolation theory. We can therefore formulate the freeze-out of interacting hadronic matter in terms of the percolation of hadronic clusters. The resulting freeze-out condition as a function of temperature and baryo-chemical potential interpolates between resonance gas behavior at low baryon density and repulsive nucleonic matter at low temperature, and it agrees well with the data.

From Regge behavior to DGLAP evolution

Abstract. We study the interface between Regge behavior and DGLAP evolution in a non-perturbative model for the nucleon structure function based on a multipole pomeron exchange. This model provides the input for a subsequent DGLAP evolution that we calculate numerically. The soft input and its evolution give a good fit to the experimental data in the whole available range of x and

Non-equilibrated post-freeze-out distributions

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Statistical hadronization of supercooled quark-gluon plasma

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Can supercooling explain the HBT puzzle

Abstract.We discuss freeze-out on the hypersurface with time-like normal vector, trying to answer how realistic it is to assume thermal post-freeze-out distributions for measured hadrons. Using simple kinetic models for gradual freeze-out we are able to generate a thermal post-FO distribution, but only in a highly simplified situation. In a more advanced model, taking into account rescattering and re-thermalization, the post-FO distribution gets more complicated. The resulting particle distributions are in qualitative agreement with the experimentally measured pion spectra. Our study also shows that the obtained post-FO distribution functions, although analytically very different from the Jüttner distribution, do look pretty much like thermal distributions in some range of the parameters.

Low-Energy Diffraction; A Direct-Channel Point of View: The Background

The fast simultaneous hadronization and chemical freeze-out of supercooled quark-gluon plasma, created in relativistic heavy ion collisions, can lead to the reheating of the expanding matter and to the change in a collective flow profile. We use the assumption of statistical nature of the hadronization process, and study quantitatively the freeze-out in the framework of hydrodynamical Bjorken model with different simple quark-gluon plasma equations of state.

QGP Hydrodynamics for RHIC energies

Abstract Possible hadronization of supercooled QGP, created in heavy ion collisions at RHIC and SPS, is discussed within a Bjorken hydrodynamic model. Such a hadronization is expected to be a very fast shock-like process, what, if hadronization coincides or shortly followed by freeze out, could explain a part of the HBT puzzle, i.e., the flash-like particle emission ( R out / R side ≈1). HBT data also show that the expansion time before freeze out is very short (∼6–10xa0fm/ c ). In this Letter we discuss the question of supercooled QGP and the timescale of the reaction.

Deeply virtual compton scattering and generalized parton distributions

We argue that at low-energies, typical of the resonance region, the contribution from direct-channel exotic trajectories replaces the Pomeron exchange, typical of high energies. A dual model realizing this idea is suggested. While at high energies it matches the Regge pole behavior, dominated by a Pomeron exchange, at low energies it produces a smooth, structureless behavior of the total cross section determined by a direct-channel nonlinear exotic trajectory, dual to the Pomeron exchange.

Generalized Distribution Amplitudes: New Tools to Study Hadrons’ Structure and Interaction

The relativistic hydrodynamic approach in this field became one of the best established theoretical and experimental method [1]. The applicability of this method is vital, so we have to discuss the initial and final stages of heavy ion reactions in great detail, in additon to the middle stages of the reaction where the relativistic hydrodynamic description provides an adequate and accurate description of the reaction.

Explicit model realizing parton hadron duality

We present a comparison of a recently proposed model, which describes the Deeply Virtual Compton Scattering amplitude, to the HERA data.