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Present data on the partonic content of the photon from LEP, TRISTAN and HERA accelerators are reviewed and the essential aspects of the underlying ideas and methods are pointed out. Results of the unpolarized photon structure fun...
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Present data on the partonic content of the photon from LEP, TRISTAN and HERA accelerators are reviewed and the essential aspects of the underlying ideas and methods are pointed out. Results of the unpolarized photon structure function F-2(gamma) from DISe gamma experiments and on large p(T) jet production processes in the resolved gamma gamma collisions are presented for both real and virtual photons. The results of analysis of the hadronic final state accompanying the DISe gamma measurements, showing some discrepancies with the Monte Carlo models, are collected together and presented as a separate issue. Also results on the DISe gamma with leptonic final states are shown. The results from resolved real and virtual photon processes at HERA collider based on the single- and double-jet events. also charged particles and prompt photons, are presented. In the context of virtual photon processes the data for forward jet and forward particle production are included, In addition, a short presentation of the recent data on the heavy quark content of the photon is given. Related topics - the polarized (spin-dependent) structure functions for the real and virtual photon, the structure function of the electron and the photonic content of the proton are also shortly mentioned. (C) 2001 Elsevier Science B.V. All rights reserved. [References: 350]
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A detailed calculation of the O(m alpha(6)) corrections to the energy levels of positronium for the orbital angular momentum number l > 0 is presented. The formulas obtained are in agreement with the known results for the particul...
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A detailed calculation of the O(m alpha(6)) corrections to the energy levels of positronium for the orbital angular momentum number l > 0 is presented. The formulas obtained are in agreement with the known results for the particular case of l=1. The complete analytical formulas to O(m alpha(6)) are given for an arbitrary l > 0 state, as well as numerical values of the energy levels 3(2S+1)D(J).
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The Fokker-Planck equation for the distribution function of two massive Brownian spheres, suspended in a fluid of much lighter spheres, is derived from the full hierarchy of exact kinetic equations for the time evolution of the fu...
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The Fokker-Planck equation for the distribution function of two massive Brownian spheres, suspended in a fluid of much lighter spheres, is derived from the full hierarchy of exact kinetic equations for the time evolution of the full system consisting of two Brownian and N fluid spheres. The separation of time scales is automatically achieved by a systematic multiple timescale analysis of the expansion in powers of the square root of the fluid-to-Brownian particle mass ratio. This procedure guarantees uniform convergence of the expansion and requires no extra physical assumptions to justify the separation of time scales. An exact expression is obtained for the mutual friction tensors, which naturally split into a static (Enskog) part and a contribution due to dynamical correlations. The present derivation of the two-particle Fokker-Planck equation also leads to an expression for the fluid-induced, effective depletion force between two Brownian particles. [References: 22]
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The generalized Mayer graphs invented by Nettleton and Green are used to express the probability distribution of statistical systems by reduced distribution functions. The entropy is expressed in terms of graphs and a simple rule ...
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The generalized Mayer graphs invented by Nettleton and Green are used to express the probability distribution of statistical systems by reduced distribution functions. The entropy is expressed in terms of graphs and a simple rule of counting them is presented. The hyper-netted chain approximations are discussed. (C) 2001 Elsevier Science B.V. All rights reserved. [References: 13]
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A semi-perturbative description of the resonance structures induced by strong laser fields is formulated within the framework of the non-Hermitian Floquet theory. Three cases are examined numerically, namely continuum structures i...
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A semi-perturbative description of the resonance structures induced by strong laser fields is formulated within the framework of the non-Hermitian Floquet theory. Three cases are examined numerically, namely continuum structures induced by a two-colour embedding field, resonance enhancements in two-colour ionization and Stark-shift-induced resonances in a strong monochromatic field. [References: 43]
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The Drude-Lorentz model of a nonpolar dielectric with the simple cubic, face-centered and body-centered crystal lattice structures is considered. The electrostatic spectral density of the renormalized polarizability is found. The ...
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The Drude-Lorentz model of a nonpolar dielectric with the simple cubic, face-centered and body-centered crystal lattice structures is considered. The electrostatic spectral density of the renormalized polarizability is found. The problem is equivalent to the calculation of the electronic density of states in the model. The obtained spectra are analyzed and the critical points are identified. The results are compared with the computer simulation data for a hard-sphere fluid. In the latter, the structure analogous to the transverse and longitudinal polarization modes characteristic for a solid dielectric is shown to exist. (C) 1998 Elsevier Science B.V. All rights reserved. [References: 21]
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The long-time translational and rotational motion of a Brownian particle in two dimensions is studied on the basis of the fluctuation-dissipation theorem and linearized hydrodynamics. The long-time motion follows from the low freq...
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The long-time translational and rotational motion of a Brownian particle in two dimensions is studied on the basis of the fluctuation-dissipation theorem and linearized hydrodynamics. The long-time motion follows from the low frequency behavior of the mobility matrix. The coefficient of the long-time tail For the translational motion turns out to be independent of shape and size of the body, in agreement with mode-coupling theory. For rotational Brownian motion the coefficient of the long-time tail is found to depend on the shape of the body, This result is in conflict with a recent prediction from mode-coupling theory, and indicates that the mode-coupling calculation should be revised. [References: 43]
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We present a 2+1 decomposition of the vacuum initial conditions in general relativity. For a constant mean curvature one of the momentum constraints decouples in quasi isotropic coordinates and it can be solved by quadrature. The ...
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We present a 2+1 decomposition of the vacuum initial conditions in general relativity. For a constant mean curvature one of the momentum constraints decouples in quasi isotropic coordinates and it can be solved by quadrature. The remaining momentum constraints are written in the form of the tangential Cauchy-Riemann equation. Under additional assumptions its solutions can be written in terms of integrals of known functions. We show how to obtain initial data with a marginally outer trapped surface. A generalization of the Kerr data is presented.
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Particle and pairing densities in spherical even-even neutron-rich nuclei are studied within the Skyrme-Hartree-Fock-Bogoliubov approach with the density-dependent pairing interaction. The influence of the density dependence of th...
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Particle and pairing densities in spherical even-even neutron-rich nuclei are studied within the Skyrme-Hartree-Fock-Bogoliubov approach with the density-dependent pairing interaction. The influence of the density dependence of the pairing interaction on asymptotic properties of nucleonic distributions are analyzed. It is demonstrated that the size of the neutron halo dramatically depends on the behavior of the pairing interaction at low density. (C) 2001 Elsevier Science B.V. All rights reserved. [References: 33]
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We investigate electron-ion recombination in a powerful bichromatic laser field of frequencies omega (L) and 3 omega (L) and consider the dependence of the recombination probabilities on the relative phase phi of the two held comp...
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We investigate electron-ion recombination in a powerful bichromatic laser field of frequencies omega (L) and 3 omega (L) and consider the dependence of the recombination probabilities on the relative phase phi of the two held components. During this process a certain number of laser photons can be absorbed or emitted, yielding a spectrum of harmonics of the form omega (x) = E-(p) over right arrow + nw(L) + I-io + U-p(tot), where E-(p) over right arrow is the initial electron energy, It the number of emitted or absorbed laser photons w(L), I-lo the ionization energy and U-p(tot) the total ponderomotive energy of the bichromatic laser field. This process is of interest for the generation of high=frequency fields during the laser heating of plasmas. We shall evaluate the nonlinear recombination probabilities as a function of the relative phase phi of the two field components using the inverse form of the Keldysh-Faisal-Reiss model, also taking into account in an approximate way the Coulomb effects of the ion on the recombining electron. Moreover, we shall compare our quantum mechanical results with those obtained from a classical theory of recombination, developed recently, based on Bohr's correspondence principle. [References: 25]
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