We investigate photo-production of vector mesons J/Psi and Psi(2s), based on both HERA LHC data, using 2 fits unintegrated gluon distributions. The latter are subject to non-linear Balitsky-Kovchegov evolution (Kutak-Sapeta gluon; KS) linear next-to-leading order Balitsky-Kuraev-Fadin-Lipatov (Hentschinski-Sabio Vera-Salas; HSS gluon) respectively. Apart from extending previous studies the case...

We consider a BRST-invariant generalization of the ``massive background Landau gauge,'' resembling original Curci-Ferrari model that saw revived interest due to its phenomenological success in modeling infrared Yang-Mills dynamics, including phase transition. Unlike model, however, mass parameter is no longer input, but it enters as result dimensional transmutation via dimension-2 gluon condens...

Hadron production in high energy collisions can be described by parton showers, followed by the formation of hadrons which cannot be described perturbatively. Gluon emission, the dominant process in parton showers, is proportional to the colour factor associated with the coupling of the emitted gluon to the emitter. These colour factors are CA = 3 when the emitter is a gluon and CF = 4/3 when i...

We show that the arguments against our recent paper on the failure of the collinear expansion in the calculation of the induced gluon emission raised by X.N. Wang are either incorrect or irrelevant. 1. In our recent paper [1] (below referred to as AZZ) we have investigated the relation between the light-cone path integral (LCPI) approach [2] (for reviews, see [3, 4, 5]) to the induced gluon rad...

We present numerical results for the two loop QCD corrections to the ghost gluon vertex, the quark gluon vertex, and the triple gluon vertex in the massless limit at the symmetric point. We restrict ourselves to the tensor structures existing in the tree level. The corrections are used to examine different coupling constant definitions in momentum subtraction schemes and the corresponding three...

We consider the possibility of a direct determination of the polarized gluon density in the proton using charm production with polarized beams at HERA. We study total cross sections and distributions at leading order using different parametrizations of the polarized gluon density. We conclude that charm photoproduction data can be used to constrain the polarized gluon density in the proton if a...

We show estimates for shadowing of gluons at small values of x, appropriate to RHIC and LHC experiments. Using a new evolution equation which takes into account the effects of gluon recombination to all orders in gluon density, we show that there is a significant depletion in the gluon density of large nuclei. Talk given at XXIX Int. Symp. on Multiparticle Dynamics (ISMD99), 9-13 August 1999, P...