abstract

Our purpose is to study the impact of chaos-generators on the dynamics of nonlinear systems. As an example two simplified models of chemical reactions have been chosen with different coupling to the external noise. Numerical analysis together with analytic predictions for a stationary situation show possibility of noise induced periodicity.

abstract

Two independent methods are employed to deduce the multiplet structure of a higher spin superspace. The first is based on the usual theta expansion. A general diagrammatic method is developed for working out the various components of the superfield. The case of the superfield with a vector spinor SUSY coordinate is worked out in detail. The second approach utilizes the Wigner method of induced representations. The two approaches are shown to give analogous results for the representations.

abstract

The diffusive properties of the soliton gas borne by a damped, unbiased Sine–Gordon theory coupled with a dissipative heat-bath are reviewed in the dilute gas approximation. It is shown that, contrary to the biased case, no anomalous diffusion occurs at time longer than the soliton lifetime. The corrections to the effective diffusion constant due to the interaction of a single soliton with a gas of both breathers (or phonons) and (anti)solitons at equilibrium are calculated analytically.

abstract

Charged particle densities achievable at the future accelerators in extremely central S + S and Pb + Pb collisions are calculated on the basis of the independent scattering scheme.

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The first- and second-order radial equations, derived from the two-body Dirac equation (called also the Breit equation), are described. A new Klein–Gordon-type form of the second-order radial equations is reported on. This is convenient for numerical calculations and may be also useful for a general discussion of the order of energy levels is quarkonia. Beside the usual perturbative case of weak Coulombic potential, the less familiar case of strong Coulombic potential is briefly discussed.

abstract

Time evolution of hoop-like configurations of the classical string with rigidity is studied. Emphasis is put on effects which are due to the presence of higher derivatives in the theory. Trajectories close to Nambu–Goto trajectories and tachyonic trajectories of the string are found. It is pointed out that the dynamics of the hoop-like string with rigidity is probably non-integrable.

abstract

The calculations of heavy-ion fusion cross sections in the above and sub-barrier regions axe presented. A barrier penetration model with matrix method for the calculations of transmission coefficients through real one-dimensional barrier of nucleus-nucleus potential is used. The renormalization parameter \(N_{\rm S}\) of Satchler–Love M3Y nuclear potential and critical radius \(R_{\rm cr}\) are the two parameters of the model. A very good description of the experimental fusion cross sections for \(lp\)-shell colliding ions was obtained for the full measured energy range. It was found that both parameters \(N_{\rm S}\) and reduced critical radius \(r_{\rm cr}\) are very similar for all systems considered and are energy independent.