[en] After briefly reviewing the status of recent experiments looking for the fifth force in ordinary matter, we discuss two classes of experiments sensitive to the presence of a coupling of kaons to the fifth force. These are attempts to detect hyperphotons (γ/sub Y/) in the decay K/sub L/ → π⁺π^-γ/sub Y/, and searches for an energy-dependence of the K⁰ - /bar K/sup 0// parameters. 29 refs

[en] Recently developed supersymmetric perturbation theory has been successfully employed to make a complete mathematical analysis for the reason behind exact solvability of some non-central potentials. This investigation clarifies once more the effectiveness of the present formalism

[en] The first-order distorted-wave approximation (DWB1) has proved to be one of the most successful approaches for the theoretical calculation of electron-atom scattering. It is now evident that one must perform multistate close-coupling calculations or second-order perturbation calculations to improve significantly upon the DWB1, but these calculations require enormous computational efforts. Consequently, it is of interest to investigate the possibility of improving the standard DWB1. One such possibility that has not been investigated for electron-atom scattering is the use of realistic nonspherical distorting potentials. In this paper, the DWB1 formalism is presented for nonspherical distorting potentials, and the effects of such a potential are investigated for electron-impact excitation of the 2p state of hydrogen

[en] Phonon dispersion in hcp solids Zr and Tb has been studied on the basis of a new phenomenological model, which introduces a non-central interaction between nearest neighbours of different types. The present results show considerable improvements over the results obtained earlier. (author)

[en] In the theories of fs demagnetization of a ferromagnetic sample after exposure to a fs laser pulse it is assumed that the angular momentum of the sample is conserved. It is shown that this is not strictly valid. However, it is argued that the effect of the deviations from strict angular momentum conservation is very small. - Highlights: • Theory of fs-demagnetization after laser pulse excitation. • Angular momentum transfer out of the electronic spin system. • Non-isolated system, non-central forces, angular momentum conservation

[en] Two particles of identical mass attract and repel each other even when there exist no classical external forces and their average relative momentum vanishes. This quantum force depends crucially on the number of dimensions of space

[en] The elastic-force model proposed in a previous paper has been considered to compute the phonon dispersion relations for lattice waves propagating along the principal symmetry directions of α-iron, chromium and tungsten. The model, however, takes into account the central forces together with the Clark, Gazis and Wallis type angular forces and the effect of electron-iron interaction on the lattice vibration as outlined by Krebs. The theoretical results are found to be quite satisfactory and compare well with recent neutron scattering data

[en] The solution of the few-nucleon problem with a realistic nucleon-nucleon interaction including spin-orbit, tensor, etc. potentials is a real challenge in nuclear physics. In this work the application of the stochastic variational method is extended to noncentral interactions and the binding energies and other physical properties of the light nuclei are calculated. The trial function is a correlated gaussian multiplied by appropriate orbital and spin-isospin functions. (K.A.)

[en] We propose a three-dimensional mechanical model of embryonic tissue dynamics. Mechanically coupled adherent cells are represented as particles interconnected with elastic beams which can exert non-central forces and torques. Tissue plasticity is modeled by a stochastic process consisting of a connectivity change (addition or removal of a single link) followed by a complete relaxation to mechanical equilibrium. In particular, we assume that (i) two non-connected, but adjacent particles can form a new link; and (ii) the lifetime of links is reduced by tensile forces. We demonstrate that the proposed model yields a realistic macroscopic elasto-plastic behavior and we establish how microscopic model parameters determine material properties at the macroscopic scale. Based on these results, microscopic parameter values can be inferred from tissue thickness, macroscopic elastic modulus and the magnitude and dynamics of intercellular adhesion forces. In addition to their mechanical role, model particles can also act as simulation agents and actively modulate their connectivity according to specific rules. As an example, anisotropic link insertion and removal probabilities can give rise to local cell intercalation and large scale convergent extension movements. The proposed stochastic simulation of cell activities yields fluctuating tissue movements which exhibit the same autocorrelation properties as empirical data from avian embryos. (paper)

[en] The analytical properties and the resonant structure of the nonrelativistic S-matrix are investigated for elastic scattering with absorption for central, noncentral and parity-violating interactions and when the equations of motion for particles inside a sphere with finite radius are unknown. The conditions for the completeness of wave functions outside the interaction sphere, for the symmetry and for the generalized unitarity of the S-matrix are used. The conditions of micro- and macro-causality for the obtained results are investigated. (author)