The constant background bag model of the hadron

We have constructed the bag model having a central constant color field. The motion of the quark is studied in this bag and the Dirac equation is solved for it. The energy spectrum found has a branching due to the interaction of the quarks with the color background. It is pointed out that this model can be applied for taking into account, in the mass spectrum of hadrons, the coupling of the constituent quarks with the gluon condensation as the interaction with the color background.Comment: 10 pages, improved English, will be published in the Eur. Phys. Jour.

Radiation zeros in weak boson production processes at hadron colliders

The Standard Model amplitudes for processes where one or more gauge bosons are emitted exhibit zeros in the angular distributions. The theoretical and experimental aspects of these radiation amplitude zeros are reviewed and some recent results are discussed. In particular, the zeros of the $WZ\gamma$ and $WZZ$ production amplitudes are analyzed. It is briefly explained how radiation zeros can be used to test the SM.Comment: Talk given at 22nd Annual MRST (Montreal-Rochester-Syracuse-Toronto) Meeting: Conference on Theoretical High-Energy Physics, Rochester, New York, 8-9 May 200

Meson effective mass in the isospin medium in hard-wall AdS/QCD model

We study a mass splitting of light vector, axial-vector and pseudoscalar mesons in isospin medium in the framework of hard-wall model. We write an effective mass definition for the interacting gauge fields and scalar field introduced in gauge field theory in the bulk of AdS space-time. Relying on holographic duality we obtain a formula for the effective mass of a boundary meson in terms of derivative operator over the extra bulk coordinate. The effective mass found in this way coincides with the one obtained from finding of poles of the two-point correlation function. In order to avoid introducing distinguished infrared boundaries in the quantisation formula for the different mesons from the same isotriplet we introduce extra action terms at this boundary, which reduces distinguished values of this boundary to the same value. Profile function solutions and effective mass expressions were found for the in-medium $\rho$, $a_1$ and $\pi$ mesons.Comment: 28 pages, clarifications added, 3rd section changed, version accepted for publication in EPJ