Comments on “role of impurities on the primary process for f-coloring in alkali halides”

Growth of the V₄ centers during and after pulsed electron irradiation of KBr was measured between 77K and 200K. It is found that the growth during pulsed irradiation is clearly different from that due to the thermal motion of the H centers. Critical discussions on the mechanism of the interstitial interaction in the primary step of the Frenkel-pair creation were made.     

Use of ɛ expansions in the theory of the gravitational effect

The equations of state found by the expansion method by Brézin, Wallace, and Wilson and Avdeeva and Migdal are applied to the investigation of the gravitational effect in the critical region. As a result, expansions are obtained for the numerical coefficients in the asymptotic behaviors of the scale functions of these equations. The results of the calculation of the coefficients are compared with available experimental data for a number of liquids and magnets.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 77–81, May, 1980.     

Self-Trapping of Acoustic Polaron in One Dimension

The ground-state energy and effective mass of an acoustic polaron in one dimension are calculated by using an electron-longitudinal-acoustic-phonon interaction Hamiltonian derived here. The self-trapping of the acoustic polaron is discussed. It is found that the critical coupling constant shifts toward weaker electron-phonon interaction with the increasing cutoff wave vector and the products of the critical coupling constant by the cutoff wave vector tend to a certain value. The self-trapping of acoustic polarons in one dimension is easier to be realized than that in three- and two-dimensional systems. The self-trapping transition of acoustic polarons is expected to be observed in the one dimensional systems of alkali halides and wide-band-gap semiconductors.     

Calculated conversion rate of E′4 centers into E′2 centers in alpha quartz

Recent cluster calculations by Rudha et al. [1] are used to obtain a pseudo-Jahn-Teller adiabatic energy profile for the interconversion between E′₄ centers and E′₂ centers based on the structural models proposed therein. Reasonable values are obtained for the underlying parameters which lends some further support to the models. A reaction rate method is next used to compute the temperature dependence of the conversion rate in either direction, as well as of the rate for reorientational flopping of Fowler's E′₁ center. Thermally-activated tunneling is found to be the main factor controlling the conversions in most of the temperature range of any practical interest.     

Polaron in an electron–exciton structure under the conditions of the Bose–Einstein condensation

A polaron state of an electron in a hybrid system composed of a two-dimensional electron gas and a Bose–Einstein condensate of excitons situated in a quantum well coplanar with the electron gas has been investigated. It has been shown that self-localization is possible even at a weak coupling between the components of the structure, when a fluctuation of the density of excitons producing a potential well for the electron is small compared to their average density.     

Widths in the conversion of Σ and Ξ hyperons in nuclear matter

The widths of the conversion processes N, N in nuclear mattter were calculated based on the model of single-boson exchange. It was established that the conversion width for is significantly reduced by the interference of the contributions of separate mesons to the conversion amplitude. The conversion width obtained for in nuclear matter turned out to be less than 1 MeV.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 79–84, March, 1988.     

Gauge hierarchies in the E8 × E′8 superstring theory

We present a systematic approach to the problem of gauge hierarchy structure in E₈ × E′₈ superstring theory. It is shown that only very limited E₆ breaking schemes are allowed from the group-theoretical and phenomenological point of view. The ordinary GUTs are not permitted and moreover the unification of SU(3), and SU(2)_w cannot occur at the energy scale below M_PI. We give four promising models and add some comments on each of them.     

Spin-Flip of Polaron in Polymers with a Magnetic Impurity

Using a nonadiabatic evolution method, we investigate the spin-flip process of polaron in polymers with a magnetic impurity. Our results show that when the spin orientation of this impurity is fixed to be perpendicular to the spin of polaron （θ = π/2）, the magnetic impurity causes a spin-flip process. The probability of the spin-flip increases with the increase of exchange integral J up to about 0.35 eV and then decreases with the increase of J. In the case J is fixed while the spin orientation is adjustable, we find the probability of the spin-flip varies with the impurity orientation and reaches a maximum value at θ=π/2.     

On the ε-expansion procedure in the RNG theory of turbulence

Rescaling the equations of eliminating small scales, the physical justification for the-expansion procedure in the RNG theory of turbulence is proposed, in terms of that the inertial effects are small comparing with the viscous effects at the vicinity of the Kolmogorov dissipation wavenumber.We are grateful to Professor Chao-Hao Gu for numerous helpful suggestions. We would also like to acknowledge Professor Ke-Lin Wang and Bing-Hong Wang for many stimulating discussions of these problems.     

To the theory of isotope effect in the thermodynamics of “Classical” crystals

Based on general expressions for quantum contributions to the free energy of a statistical system, an approach is developed making it possible to carry out a complete theoretical analysis of the equilibrium thermodynamic characteristics of argon-type crystals as a function of the isotopic mass. The theory is based on independently calculated (in fact, without fitting parameters) one-particle and two-particle distribution functions of the classical crystal and permits one to quantitatively describe the data on the lattice parameters of isotope crystals obtained from numerical experiments. It is pointed out that real experiments are needed to study the isotope effect in crystals of noble gases, especially in view of the fact that, according to the literature data, xenon undergoes an fcc-hcp phase transition under increased pressure.     

“Conserved charges” of the Bondi-Metzner-Sachs algebra in the Brans-Dicke theory

The asymptotic symmetries in the Brans-Dicke theory are analyzed using Penrose's conformal completion method,which is independent of the coordinate system used.These symmetries,indeed,include supertranslations and Lorentz transformations for an asymptotically flat spacetime.With the Wald-Zoupas formalism,“conserved charges”and fluxes of the Bondi-Metzner-Sachs algebra are computed.The scalar degree of freedom contributes only to the Lorentz boost charge,even though it plays a role in various fluxes.The flux-balance laws are further applied to constrain the displacement memory,spin memory,and center-of-mass memory effects.     

Existence of the critical point in φ4 field theory

We consider the ⁴ quantum field theory in two and three spacetime dimensions. In the single phase region the physical mass (inverse correlation length)m() decreases continuously to zero as the bare mass parameter approaches a critical value _c from above. In three dimensions the critical point _c is in the single phase region and the physical mass vanishes there,m( _c )=0.A consequence of our results is that the critical exponentv governing the approach to infinite correlations is bounded below (rigorously) by its classical value, 1/2.Supported in part by the National Science Foundation under Grant MPS74-13252     

Resonances in the pump-probe spectroscopy of Λ system in alkali atoms

We investigate resonances in the pump-probe spectroscopy of Λ configuration of levels in the hyperfine manifold of D ₂ transition of ¹³³Cs and ^a7Rb with specific reference to Autler-Townes splitting, dressed state resonances in double Λ system and electromagnetically induced transparency. As an application, a dark resonance based magnetometer is briefly discussed.     

Partial treatment of the fluctuation potential in the Debye-Hückel theory of electrolyte solutions

The treatment of the two-sphere fluctuation potential problem in the Debye-Hückel theory is taken into account in a more satisfactory manner. The results are seen to parallel those of Kirkwood.     

Analysis of Polaron Band Formation with the One-Dimensional Holstein Model

We present an analytic result of the polaronic band structure by using the one-dimensional Holstein model on an infinite lattice. The single-phonon effect is used to investigate the ground state properties, such as the polaronic band structure, ground state energy, phonon distribution and effective mass, which agree with the numerical and analytic results obtained recently in the region from the weak coupling to the intermediate coupling.