Propagation of the heavy quark in the field of a static antiquark source is studied in the framework of effective Dirac equation. The model of QCD vacuum is described by bilocal gluonic correlators. In the heavy quark limit the effective interaction is reduced to the potential one with 5/6 Lorentz scalar and 1/6 Lorentz vector linear confinement, while spin–orbit term is in agreement with Eicht...

An incomparable feature of the chiral quark soliton model as compared with many other effective models like the MIT bag model is that it can give reasonable predictions not only for quark distributions but also for antiquark distributions. This will be exemplified by the argument on the positivity constraint for ū(x) + d̄(x) as well as the Soffer inequality for quark and antiquark distributions....

We investigate the role of the flavor asymmetry of the nucleon's polarized antiquark distributions in Drell–Yan lepton pair production in polarized nucleon–nucleon collisions at HERA (fixed–target) and RHIC energies. It is shown that the large polarized antiquark flavor asymmetry predicted by model calculations in the large–N c limit (chiral quark–soliton model) has a dramatic effect on the dou...

We generalize the usual octet, decuplet and exotic antidecuplet and higher baryon multiplets to any number of colours Nc. We show that the multiplets fall into a sequence of bands with O(1/Nc) splittings inside the band and O(1) splittings between the bands characterized by “exoticness”, that is the number of extra quark-antiquark pairs needed to compose the multiplet. Each time one adds a pair...

We have studied in perturbative QCD all independent helicity amplitudes describing the photoproduction of light vector mesons at large t. We found a new hard production mechanism which is related to the possibility for a real photon to fluctuate into a massless q ¯ q pair in a chiral-odd spin configuration. Each helicity amplitude is given as a sum of chiral-even contribution (when the heliciti...

The spectrum of gluon excitations in the presence of a static quark-antiquark pair is presented. Our results are obtained from computer simulations of gluons on anisotropic space-time lattices using an improved gauge-field action. Measurements for quark-antiquark separations r ranging from 0.1 fm to 4 fm and for various orientations on the lattice are made. Discretization errors and finite volu...

We show that the infinite imaginary anomalous dimensions of certain heavy quark-antiquark currents in the HQET arise due to an inappropriate commutation of two limits, namely coinciding velocities and infinite cutoff. This commutation is not apparent when dimensional regularization is used, but it can be made manifest in a cutoff regularization. We argue that operators containing heavy quark an...