Researches regarding structural modifications that appears in the material of tools used for rubber waste attrition

Tools commonly used for shredding rubber waste, currently produced, are made of neatly cast iron in the composite is to avoid the presence of sulfur and phosphorus. In this paper are presented the main structural material changes that occur in different areas, located at different distances from the active surface of tools. Structural changes occurred mainly refers to the transformation of white iron surface layer to gray cast iron and graphite separations appearance, which causes the crack primers and cracking corrosion phenomena in tools material

Researches on the chemical composition and hardness modifications that appear in the material of tools used for rubber waste attrition

This paper presents the results of the main changes in the chemical composition of the material, and changes in its hardness. The changes in terms of chemical composition refer primarily to changes in concentration of sulfur and carbon, and in terms of hardness material change there can be noticed a decrease in hardness of the material that is in direct contact with waste rubber

Researches on the chemical composition and hardness modifications that appear in the material of tools used for rubber waste attrition

This paper presents the results of the main changes in the chemical composition of the material, and changes in its hardness. The changes in terms of chemical composition refer primarily to changes in concentration of sulfur and carbon, and in terms of hardness material change there can be noticed a decrease in hardness of the material that is in direct contact with waste rubber

JIMWLK evolution in the Gaussian approximation

We demonstrate that the Balitsky-JIMWLK equations describing the high-energy evolution of the n-point functions of the Wilson lines (the QCD scattering amplitudes in the eikonal approximation) admit a controlled mean field approximation of the Gaussian type, for any value of the number of colors Nc. This approximation is strictly correct in the weak scattering regime at relatively large transverse momenta, where it reproduces the BFKL dynamics, and in the strong scattering regime deeply at saturation, where it properly describes the evolution of the scattering amplitudes towards the respective black disk limits. The approximation scheme is fully specified by giving the 2-point function (the S-matrix for a color dipole), which in turn can be related to the solution to the Balitsky-Kovchegov equation, including at finite Nc. Any higher n-point function with n greater than or equal to 4 can be computed in terms of the dipole S-matrix by solving a closed system of evolution equations (a simplified version of the respective Balitsky-JIMWLK equations) which are local in the transverse coordinates. For simple configurations of the projectile in the transverse plane, our new results for the 4-point and the 6-point functions coincide with the high-energy extrapolations of the respective results in the McLerran-Venugopalan model. One cornerstone of our construction is a symmetry property of the JIMWLK evolution, that we notice here for the first time: the fact that, with increasing energy, a hadron is expanding its longitudinal support symmetrically around the light-cone. This corresponds to invariance under time reversal for the scattering amplitudes.Comment: v2: 45 pages, 4 figures, various corrections, section 4.4 updated, to appear in JHE

Color Glass Condensate and BFKL dynamics in deep inelastic scattering at small x

The proton structure function F_2(x,Q^2) for x < 0.01 and 0.045< Q^2 < 45 GeV^2, measured in the deep inelastic scattering at HERA, can be well described within the framework of the Color Glass Condensate.Comment: 4 pages, 1 figure, incl. IOP style files. Talk given at the 17th International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions (Quark Matter 2004), Oakland, CA USA, 11-17 Jan 200

The onset of classical QCD dynamics in relativistic heavy ion collisions

The experimental results on hadron production obtained recently at RHIC offer a new prospective on the energy dependence of the nuclear collision dynamics. In particular, it is possible that parton saturation -- the phenomenon likely providing initial conditions for the multi--particle production at RHIC energies -- may have started to set in central heavy ion collisions already around the highest SPS energy. We examine this scenario, and make predictions based on high density QCD for the forthcoming 22 GeV run at RHIC.Comment: 4 pages, 2 figures, revte

Energy dependence of the saturation scale and the charged multiplicity in pp and AA collisions

A natural framework to understand the energy dependence of bulk observables from lower energy experiments to the LHC is provided by the Color Glass Condensate, which leads to a "geometrical scaling" in terms of an energy dependent saturation scale Q_s. The measured charged multiplicity, however, seems to grow faster (~\sqrt{s}^0.3) in nucleus-nucleus collisions than it does for protons (~\sqrt{s}^0.2), violating the expectation from geometric scaling. We argue that this difference between pp and AA collisions can be understood from the effect of DGLAP evolution on the value of the saturation scale, and is consistent with gluon saturation observations at HERA.Comment: RevTeX, 8 pages, 4 figures. V2: modified discussion of fragmentation, published in EPJ

Non-linear QCD dynamics in two-photon interactions at high energies

Perturbative QCD predicts that the growth of the gluon density at high energies should saturate, forming a Color Glass Condensate (CGC), which is described in mean field approximation by the Balitsky-Kovchegov (BK) equation. In this paper we study the $\gamma \gamma$ interactions at high energies and estimate the main observables which will be probed at future linear colliders using the color dipole picture. We discuss in detail the dipole - dipole cross section and propose a new relation between this quantity and the dipole scattering amplitude. The total $\gamma \gamma$, $\gamma^{*} \gamma^{*}$ cross-sections and the real photon structure function $F_2^{\gamma}(x,Q^2)$ are calculated using the recent solution of the BK equation with running coupling constant and the predictions are compared with those obtained using phenomenological models for the dipole-dipole cross section and scattering amplitude. We demonstrate that these models are able to describe the LEP data at high energies, but predict a very different behavior for the observables at higher energies. Therefore we conclude that the study of $\gamma \gamma$ interactions can be useful to constrain the QCD dynamics.Comment: 11 pages, 5 figures. Version to be published in European Physical Journal

Saturation and parton level Cronin effect: enhancement vs suppression of gluon production in p-A and A-A collisions

We note that the phenomenon of perturbative saturation leads to transverse momentum broadening in the spectrum of partons produced in hadronic collisions. This broadening has a simple interpretation as parton level Cronin effect for systems in which saturation is generated by the "tree level" Glauber-Mueller mechanism. For systems where the broadening results form the nonlinear QCD evolution to high energy, the presence or absence of Cronin effect depends crucially on the quantitative behavior of the gluon distribution functions at transverse momenta kt outside the so called scaling window. We discuss the relation of this phenomenon to the recent analysis by Kharzeev-Levin-McLerran of the momentum and centrality dependence of particle production in nucleus-nucleus collisions at RHIC.Comment: 22 pages LaTex, 7 eps-figures, discussion of evolved gluon distribution revised significantl