abstract

We discuss some mechanisms of isotropization in the class of \(n\)-dimensional Bianchi I models. We show that these models can isotropize but this process leads to the breakdown of dimensional reduction. Thus we ought to look for such a mechanism of dimensional reduction that isotropizes the space.

abstract

An expression has been obtained for mean multiplicity of g-particles accompanying the process of deep-inelastic lepton pair production on nuclei. The expression allows one to get information on structure peculiarities of leading hadron in this process.

abstract

Assuming a \(k^L\) singularity for the infrared behaviour of the gluon propagator, it is shown that for \(L \gt 3\) in Abelian gauge theories the quark propagator is an entire function of \(p^2\) in the infrared region corresponding to a confining potential. An improved equation is solved for \(L=4\) and the solution is still regular on the mass shell. The four quark Green’s function is studied for \(L = 4\) in a Bloch–Nordsieck type model and it is shown that the cross section of quark-quark scattering vanishes even if an arbitrary number of soft gluons is included, a phenomenon we interpret as an evidence of confinement.

abstract

In the chiral bag the fermionic vacuum is polarized by an external meson field. A method is described for evaluation of physical effects due to the vacuum polarization in spherical chiral bags. We apply our method to the calculation of the vacuum baryon number. The possibility is discussed that the vacuum in chiral bags can be non-trivial with respect to other quantum numbers.

abstract

The schematic model of pure hard core neutron matter proposed by Dąbrowski et al. is generalized to finite temperature, where the attractive part of nuclear forces is treated as a perturbation. We calculate the potential energy, the energy per neutron, the volume and symmetry pressure, the magnetic susceptibility, the effective mass and the velocity of sound as a function of temperature. Our results are compared with previous calculations.

abstract

The gauge covariant set of kinetic equations of a quark plasma is discussed. The collision term is included using the relaxation time approximation. The color conductivity coefficient is studied.