R e g u l a r p a p e r s

Theoretical and mathematical physics

Moscow University Physics Bulletin 1996. **1996**. N 4. P. 1

Explicit expressions have been given for the Finslerian invariant scalar products of four-dimensional momenta and radius-vectors.

Show AbstractMoscow University Physics Bulletin 1996. **1996**. N 4. P. 5

General formulas for frequencies, intensities, and phase factors of two-dimensional first-order spectra in correlation spectroscopy of nuclear magnetic resonance for pulsed proccsses $(\pi/2)_x-t_1-(\pi/2)_x – t_2$ have bееn oЪtained.

Show AbstractMoscow University Physics Bulletin 1996. **1996**. N 4. P. 10

The special features of states when the Schrodinger uncertainty relation $\Delta^2A\Delta^2B\ge(\hbar^2/4)|\langle C\rangle|^2/(1-r^2)$ $(\hat{C}=[\hat{A},\hat{B}]/i\hbar$ i1i and r is the correlation coefficient between А and В) turns into the equality have been examined. It has been shown that if, indcpendently of state, we can obtain (С) = О bу changing the point of reference, then the state $|\Psi\rangle$, for which the Schrodinger relation is the equality, is an eigenstate of the operator А or В and does not correspond to an analytical solution of the equation $\hat{A}=\hat{p}^2,$ $\hat{B}=\hat{x}$, whcre а: is а c-number. It was demonstrated that for $\hat{A}=\hat{p}^2, and $\hat{B}=\hat{x}$, the state, when the equality $\Delta^2 p^2\Delta^2 x^2=(\hbar^2/4)|\langle \hat{p}\rangle|^2$ holds asymptotically, can bе considered as the limit of the Gaussian state when $\Delta p \to 0$.

Show AbstractMoscow University Physics Bulletin 1996. **1996**. N 4. P. 14

The process of quark-antiquark pair production Ьу а massive photon in constant chromomagnetic fields that model the gluon condensate field has been considered. Pair production thresholds have been revealed and the pair production rate as а function of the field condensate strength has been calculated. The contribution of the gluon condensate to the cross section of the quark pair production in the case of comparatively weak fields at large energies of the $e^+e^-$ pair has been estimated. The nonanalytical dependence of the cross section on the condensate field, which reveals itself near the quark pair production thresholds, has been demonstrated.

Show AbstractMoscow University Physics Bulletin 1996. **1996**. N 4. P. 20

The cross section for the reaction $\gamma+e\to e+a$ on polarized relativistic electrons in а constant magnetic field in the framework of а model with а tree-level axion-electron coupling has been calculated. The dependence of the form of the spectrum and of the total cross section on invariant kinematic and dynamic paramcters dctermiпed bу the particlc encrgies and the external field strength has been studied.

Show AbstractMoscow University Physics Bulletin 1996. **1996**. N 4. P. 26

In the framework of а quantum model with memory а relation between а wave function of а quantum object and the information stored in its memory is established. On this basis two reasons (objective and subjective) for the wave function to collapse are revealed. The conclusions are illustrated bу the analysis of the Einstein-Podolsky-Rosen paradox.

Show AbstractRadiophysics

Moscow University Physics Bulletin 1996. N 4.

The features of interaction between the electron stream waves and а backward wave in а periodic lossy waveguide for а critical coupling at frequencies of the transparency band boundary are discussed.

Show AbstractMoscow University Physics Bulletin 1996. **1996**. N 4. P. 36

The feasibility of synthesizing а low-frequency sensitivity equivalent of а parametric electrodynamic transducer is discussed. А linear two-terminal network with constant parameters and appropriate noise generators is such an equivalent. Formulas for calculating thc energy spectra of such sources have been obtai11ed.

Show AbstractOptics and spectroscopy

Moscow University Physics Bulletin 1996. **1996**. N 4. P. 40

А system of equations has been derived, which describes the quasi-collinear acoustooptic interaction and relates the Fourier spectra of the amplitudes of transmitted and diffracted light beams for the case of their propagation in an anisotropic medium with walk-off of the acoustic energy. The solution of these equations with the corresponding boundary conditions provides а picture of the efficicncy of quasi-collinear diffraction under tl1e conditions of strong interaction.

Show AbstractMoscow University Physics Bulletin 1996. **1996**. N 4. P. 46

The structural, electrophysical, and optical properties of heterostructures of semiconductor-Langmuir-Blodgett film type have been studied. Oriented films of stcaric acid, doped with copper ions, have been synthesized for the first time on tl1e surfacc of germanium, and their structural characteristics have been determined. The role of doping in the formation of additional trapping sites of charge carriers at the semiconductor /film interface and in the film proper has been estaЫished. The luminescence of copper complexes in the film has been studied. The role of dimensional effects is pointed out.

Show AbstractMoscow University Physics Bulletin 1996. **1996**. N 4. P. 52

The authors consider the stimulated R.aman scattering (SRS) of powerful laser radiation in а hot inhomogeneous plasma. An expression was oЪtained for the SRS increment, wl1ich takes account of the electron plasma wave damping, the plasma inhomogeneity and of the pumping radiation modulation.

Show AbstractSolid state physics

Moscow University Physics Bulletin 1996. **1996**. N 4. P. 57

The effect of exchange amplification of electron-phonon interaction in hightemperature superconducting systems has been considered and the upper bound of applicabllity of quasi-linear equations has been determined. It has been show11 that these equations are valid if the resonance value of tl1e wave vector $k_r=max(k_{r_{1}},k_{r_{2}})\ll p_F/\hbar$, where PF is tl1e Fermi momentum, as $k_r\sim k_c$, то $\hbar k_c/p_F$. It follows that the quasi-linear theory of high-temperature systems can Ье used to calculate the critical temperature $Т_с$ when the spin-phonon coupling parameter ($\zeta\gg 1$, and to determine the criteria for synthesizing new high-temperature superconducting materials.

Show AbstractGeophysics

Moscow University Physics Bulletin 1996. **1996**. N 4. P. 61

А critical analysis is done on the traditional approach, based on Ohm's law, to the investigation of telluric fields and currents. А new way of looking has been proposed, which leans upon the baroelectric redistribution of charges in the Earth duc to tidal cffects.

Show AbstractMoscow University Physics Bulletin 1996. **1996**. N 4. P. 66

The effect of turbulence on the settling rate of particles in а suspension current is discussed. А model based on the equation of motion for а single particle in а viscous fluid is analyzed. А formula has been derived for calculating the nonlinearity parameter which determines the dependcnce of the drag force of а moving particle on its settling ratc. The dependence of the nonlinearity parameter on the Reynolds number of а flow has been calculated from the experimental values of settling rates for particles of various sizes in а turbulent flow.

Show AbstractMoscow University Physics Bulletin 1996. **1996**. N 4. P. 69

The problem of describing the nonlinear processes which control the propagation of solitary waves оп water is considered. The classical theory of Korteweg-de Vries is generalized for the case when the nonlinear interaction of amplitude and frequency dispersions is taken into account. The derived formulas which predict the solitary waves of а new type are checked in laboratory experiments.

Show AbstractAstronomy

Moscow University Physics Bulletin 1996. **1996**. N 4. P. 75

The formation of the polarization of the cosmic microwave background radiation {the CMBR) during а standard recombination is considered. The amplitudes of multipole harmonics were calculatcd for various indices of the spcctrum {n = 1 and 1.5) and various types of perturbations: scalar perturbations and gravitational waves.

Show AbstractB r i e f r e p o r t s

Theoretical and mathematical physics

Moscow University Physics Bulletin 1996. **1996**. N 4. P. 81

А new class of solutions of an exact system of dynamic equations for а stratified liquid that describe circular nonlinear transversal steady-state waves has been found. An approximate equation for the profile of such waves and also а nonlinear dispersion rclation have been derived.

Show AbstractRadiophysics

Moscow University Physics Bulletin 1996. **1996**. N 4. P. 84

The procedure based on the use of potentials for periodic systems of linear charges allows us to derive exact formulas for the parameters of an electrostatic undulator. The design of а longitudinal-transverse undulator with oval and corrugated electrodes has been discussed and optimized.

Show AbstractSolid state physics

Moscow University Physics Bulletin 1996. **1996**. N 4. P. 87

The transmission of zinc diarsenide has been measured at а frequency of 26.3 GHz at 300 К. The components of its dielectric constant (permittivity) have been determined in directions parallel and perpendicular to the axis с. The authors have also calculated, within the Drude model, the tensor components of the lattice permittivity $(\epsilon_{\parallel}=13,1\pm0,6$, $\epsilon_{\perp}=11,3\pm0,6$, $\epsilon_{\parallel}/\epsilon_{\perp}=1,10\div1,16)$ and those ofresistivity $[\rho_{\parallel}=(7,5\pm0,5)Ом\cdot см;$ $\rho_{\perp}= ( 52 \pm 4)Ом\cdot см;$ $ \rho_{perp}/\rho_{\parallel}=6,8\div 7,2]$.

Show AbstractMoscow University Physics Bulletin 1996. **1996**. N 4. P. 90

The nuclear spin echo method was used to measure the distribution of superfine fields on the $^{55}Mn$, $^{121}Sb$ и $^{123}Sb$ nuclei in the new semimetallic ferromagnets $NiMnSb_{1-x}Si_x$. It has becn demonstrated that the local magnetic moments are largely determined bу the local atomic cnvironment of the ion rather than bу the overall composition of the samplc and its average macroscopi1: characteristics.

Show AbstractMoscow University Physics Bulletin 1996. **1996**. N 4. P. 93

The possibility for observation of superparamagnetism of ultrafine particles at temperatures Т above their Curie point Тc { "induced superparamagnetism") is discussed. The experimental conditions for observing this phenomenon have bееn analyzed within the framework of Langevin's model complemented with the molecular field theory. The assessments show that to observe "induced superparamagnetism" the easily attainable fields are required.

Show AbstractGeophysics

Moscow University Physics Bulletin 1996. **1996**. N 4. P. 96

Using an experimental angle-measuring device, the time dynamics of the spectral properties of ionospheric disturbances is studied along а slanted radiosounding path with the aim of testing the stationarity of the process.

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