Volume 30, Issue 4, July 1999
30(1999); http://dx.doi.org/10.1134/1.953111View Description Hide Description
The basic principles of the quark–gluon string model, a perturbative QCD approach to describing hadronic processes, are presented. The relation between the -channel topological expansion of the hadron–hadron scattering amplitude and the -channel expansion in Regge poles is demonstrated, where is the number of quark flavors or colors. This approach is used to analyze soft hadronic processes. The attempts to extend the region of applicability of this model to describe the inclusive spectra of resonances and also semihard hadronic processes are briefly reviewed. In particular, a new modification of the model in which Pomeron exchange is treated as the exchange of two nonperturbative gluons with dynamically generated mass is discussed. Soft and semihard processes, and also charmed-particle production in hadron collisions, are analyzed in this version of the model. The advantages and defects of this approach compared to other perturbative QCDmodels are discussed.
30(1999); http://dx.doi.org/10.1134/1.953110View Description Hide Description
The recent experimental data on the total reaction cross sections and the interaction cross sections for light exotic nuclei are reviewed. The various approaches—phenomenological and semi-microscopic—to calculating these quantities are described. The rms radii of the neutron,proton, and matter distributions extracted from comparison with the data are analyzed for a large group of nuclei. Possible candidates for nuclei with a neutron or protonhalo are discussed. New experiments involving light exotic nuclei are proposed.
30(1999); http://dx.doi.org/10.1134/1.953112View Description Hide Description
The binary and ternary cold fragmentations of heavy nuclei are studied in the framework of a deformation-dependent cluster model in which the final fragments are produced in their respective ground states and interact via a double-folded potential with M3Y forces. The deformation effects are taken into account up to multipolarity It is shown that two regions of cold fragmentation arise. The first one has large quadrupole and even hexadecapole deformations and mass number of the heavy fragment ranging between 138 and 158. In the second region, the Q-value principle dictates the occurrence of a few spherical nuclei around the doubly magic nucleus which is similar to the case of heavy-cluster radioactivity, where the daughter nuclei are around This structure is similar for binary and ternary cold fission. The cold-fission yields are computed for the binary fragmentation and for the alpha-accompanied fission of For the ternary cold-fission mode we derive the most likely geometrical and dynamical characteristics of the fragments at the moment of release of the light particle and perform classical trajectory calculations, in order to compute the final kinetic energy of the alpha particle. The recent observation of in cold ternary fission is discussed in connection with the concept of a giant nuclear molecule.
30(1999); http://dx.doi.org/10.1134/1.953113View Description Hide Description
A few topics of the transport theory of quark–gluon plasma are reviewed. A derivation of the transportequations from the underlaying dynamical theory is discussed within the model. Peculiarities of the kinetic equations of quarks and gluons are considered, and the plasma (linear) response to the color field is studied. The chromoelectric tensor permeability is found, and the plasma oscillations are discussed. Finally, the filamentation instability in the strongly anisotropic parton system from ultrarelativistic heavy-ion collisions is discussed in detail.
30(1999); http://dx.doi.org/10.1134/1.953114View Description Hide Description
The results of studies devoted to describing the large-scale motions of the nuclear matter of neutron stars are reviewed. The approach is based on the idea that stellar nuclear matter is an elastic Fermi continuum possessing the properties of a compensated magneto-active plasma. The fundamental dynamical equations of motion of self-gravitating nuclear matter are taken to be the equations of nuclear elastodynamics, formulated in the macroscopic theory of nuclear collective processes. A variational method is presented for calculating the frequencies of gravitational-elastic spheroidal (-mode) and torsional (-mode) vibrations of a neutron star, and the star’s stability with respect to linear deformations is studied. The effectiveness of the elastodynamical method is illustrated by calculations of the periods of global gravitational elastic vibrations within the standard homogeneous model, and also for a family of realistic models of neutron stars, constructed on the basis of the relativistic equation of gravitational equilibrium and the nuclear-matter equations of state taking into account the heterophase nature of the nuclear statistical equilibrium. The motions of the magnetized Ae phase of the neutron-star matter are described using the magneto-hydrodynamical approach, which is used to calculate the frequencies of toroidal and poloidal Alfvén oscillations. It is emphasized that magneto-plasma vibrations can significantly affect the electromagnetic activity of pulsars.