Many-neighbour interaction and non-locality in traffic models

The optimal-velocity model, as proposed by Bando et al. [1], shows unrealistic values of the acceleration for various optimal-velocity functions [2,3]. We discuss different approaches of how to correct this problem. Multiple look-ahead (many-neighbour interaction) models are the most promising candidates in reducing accelerations and decelerations to realistic values. We focus on two such models and, in particular, their linear stability and how these affect the vehicle dynamics and wave solutions. As found earlier [4], multiple look-ahead models reproduce many real flow features, and our results further support the necessity of this ansatz. However, the problem of non-locality arises when they are transformed into the corresponding continuum model. We discuss three methods of how to interpret many-neighbour interaction in macroscopic models.Received: 27 March 2004, Published online: 12 July 2004PACS: 45.70.Vn Granular models of complex systems; traffic flow - 89.90. + n Other topics in areas of applied and interdisciplinary physics - 47.50. + d Non-Newtonian fluid flows     

Polarization at high transverse momentum through weak interaction and its interference with strong interaction

At transverse momenta of typical 20 to 40 GeV/c the hard scattering of quarks leads to partially polarized jets. The responsable mechanisms areW ^± andZ ⁰ exchange and their interference with gluon exchange. For the jet fragmentation we employ a model with favoured and disfavoured fragmentation according to broken SU (6). For vector mesons and Λ particles a modest polarization is predicted of the order up to ～8%.     

Duality between the weak and strong interaction limits for randomly interacting fermions

We establish the existence of a duality transformation for generic models of interacting fermions with two-body interactions. The eigenstates at weak and strong interaction U possess similar statistical properties when expressed in the U=0 and U= infinity eigenstates bases, respectively. This implies the existence of a duality point U(d) where the eigenstates have the same spreading in both bases. U(d) is surrounded by an interval of finite width which is characterized by a non-Lorentzian spreading of the strength function in both bases. Scaling arguments predict the survival of this intermediate regime as the number of particles is increased.     

Dipole relaxation in weak and strong fields

The process of dipole relaxation in a homogeneous dielectric is studied on the basis of a two-state dipole model. The external field is not assumed to be weak. Two types of applied electric fields are considered: a linearly increasing field, and a field which changes by steps. At the present time pulsed electric fields have found wide application in electron-ion technology.Translated from Izvestiya VUZ. Fizika, No. 1, pp. 95–100, January, 1972.     

Meson-lepton interaction in the spinor strong interaction theory

The recently developed spinor strong interaction theory, which successfully accounts for linear confinement and classification of mesons as well as unmixed meson spectra, is applied to semileptonic decays of the π,K, D, andB mesons. These mesons themselves generate massM _w for the mediating gauge boson; no Higgs boson is needed. The theory is also applied to purely leptonic interactions. It is shown that the results of the standard electroweak model can be taken over with the Higgs boson replaced by the above mesons. The Cabbibo angle ϑ_C is given by tan ϑ_C=(pion mass)/(kaon mass), in agreement with data. The pion decay constantF is essentially a ratio between two large constants introduced to make certain infinite integrals finite.M _w is also related to a similar cutoff constant. Dragarbrunnsg. 9B.     

Identification of strong and weak interacting two-level systems in KBr:CN

Tunneling two-level systems (TLSs) are believed to be the source of phenomena such as the universal low temperature properties in disordered and amorphous solids, and 1/f noise. The existence of these phenomena in a large variety of dissimilar physical systems testifies for the universal nature of the TLSs, which however, is not yet known. Following a recent suggestion that attributes the low temperature TLSs to inversion pairs [M. Schechter and P.?C.?E. Stamp, arXiv:0910.1283.] we calculate explicitly the TLS-phonon coupling of inversion symmetric and asymmetric TLSs in a given disordered crystal. Our work (a)?estimates parameters that support the theory in M. Schechter and P.?C.?E. Stamp, arXiv:0910.1283, in its general form, and (b)?positively identifies, for the first time, the relevant TLSs in a given system.     

Pair production at strong coupling in weak external fields

The rate of electron-positron pair production in a weak external electric field at large values of e is computed. The method is extended to compute the rate of monopole-antimonopole pair production in a weak external magnetic field at large magnetic charge.     

From weak to strong pinning I: A finite size study

We have used linear stability analysis to study the depinning of an elastic chain with long range interactions submitted to a random pinning potential. In this paper, we provide, for the first time, evidence of a pronounced change from a strong pinning regime to a weak pinning regime. This change depends on the strength of disorder, and takes place only in finite size systems. For a given disorder, we show a characteristic length separating the weak pinning regime from the strong pinning regime. This length depends on the long range of the algebraic decay of the elastic couplings. The weak pinning regime is very well described by perturbation theory. As an example, we discuss more specifically the case of wetting of heterogeneous surfaces, where the change from a strong to a weak pinning regime could be induced in the wetting front by varying the surface tension of the liquid-air interface.Received: 12 September 2003, Published online: 20 April 2004PACS: 05.10.-a Computational methods in statistical physics and nonlinear dynamics - 68.08.Bc Wetting - 02.50.Fz Stochastic analysis     

The Thomas-Fermi atom in a strong magnetic field: The weak ionization limit

It is proved that the binding energy, radius and chemical potential of the N-electron Thomas-Fermi atom with the nuclear charge Z in a strong magnetic field at q = 1 − N/Z 1 may be expressed as a power series in q^1/3 and In q. The exact values of the first expansion coefficients are found. A comparison with numerical data shows these expansions to be applicable up to q = 0.2.     

Crossover from weak to strong Kondo behaviour in CeAl2

High pressure electrical resistance experiments performed on a single crystal of CeAl₂ allow one to determine a characteristic line in the pressure-temperature plane where a continuous passage from weak to strong Kondo behaviour is observed. This line is not associated with any sizeable volume anomaly as shown by X-ray experiments.     

Crystal-field model of invar effects in weak and strong ferromagnets

This paper is principally concerned with the role of crystal fields in Invar-type behaviour. It is divided into two sections. The first seeks to examine the connection between Invar effects and weak ferromagnetism by the use of a simple crystal field model with volume-dependent exchange. By varrying the ratio of the exchange energy to the field splitting it is possible to reproduce the characteristic behaviour of weak and strong ferromagnets and exchange-enhanced paramagnets. The second part discusses some recent experimental results which are closely related to the theoretical model.     

Aperture-averaging effects for weak to strong scintillations in turbulent atmosphere

Under the approximations of (1) the received irradiance fluctuations of an optical wave caused by small scale turbulent eddies are multiplicatively modulated by the fluctuations caused by large scale turbulent eddies;(2) the scintillations caused by small- and large-scale eddies, respectively, are statistically independent; (3)the Rytov method for optical scintillation collected by the finite-diameter receiving aperture is valid for light wave propagation under weak to saturation fluctuation regime, we develop the applicable apertureaveraging analytic formulas in the week-to-strong-fluctuation for the scintillations of plane and spherical waves, which include the outer- and inner-scale rules of turbulence.     

Soliton-like excitations in the strong spin-phonon interaction

Soliton-like solutions are shown to exist in a one-dimensional chain of spins $\text{1}\text{2}$ strongly coupled to the lattice phonons. The features of these solutions are investigated and discussed.     

Pairing correlations in finite systems: from the weak to the strong fluctuations regime

The Particle Number Projected Generator Coordinate Method is formulated for the pairing Hamiltonian in a detailed way in the projection after variation and the variation after projection methods. The dependence of the wave functions on the generator coordinate is analyzed performing numerical applications for the most relevant collective coordinates. The calculations reproduce the exact solution in the weak, crossover and strong pairing regimes. The physical insight of the ansatz and its numerical simplicity make this theory an excellent tool to study pairing correlations in complex situations and/or involved Hamiltonians.     

Magnetic absorption of hexagonal crystals CdSe in strong and weak fields: Quasi-cubic approximation

The spectra of ultrathin free samples of hexagonal CdSe in a magnetic field up to 8 T are studied at 1.7 K. The fan-shaped diagram contains information on weak (the Zeeman effect and diamagnetic shift), as well as strong fields (transitions between Landau levels). As a result of the application of two theoretical models for combined interpretation of strong-and weak-field experimental data, two sets of (band and polaron) parameters are calculated for hexagonal CdSe in the quasi-cubic approximation. The values of the obtained polaron/band parameters are: the electron effective mass m _e =0.125/0.116m ₀, the Luttinger parameters γ₁=1.5/1.72, γ=0.29/0.37, κ=?0.63, and the effective electron g-factor g _e =0.7.