Scattering states of modified Pöschlben Teller potential in D-dimension

We present a new approximation scheme for the centrifugal term, and apply this new approach to the Schrödinger equation with the modified Pöschl-Teller potential in the D-dimension for arbitrary angular momentum states. The approximate analytical solutions of the scattering states are derived. The normalized wave functions expressed in terms of the hypergeometric functions of the scattering states on the k/2π scale and the calculation formula of the phase shifts are given. The numerical results show that our results are in good agreement with those obtained by using the amplitude-phase method (APM).     

一个改进的聚合物结晶生长的相场模型

The irrationality of existing phase field model is analyzed and a modified phase-field model is proposed for polymer crystal growth, in which the parameters are obtained from real materials and very simple to use, and most importantly, no paradoxical parameters appeared in the model. Moreover, it can simulate different microstructure patterns owing to the use of a new different free energy function for the simulation of morphologies of polymer. The new free energy function considers both the cases of T<T_m and T≥T_m, which is more reasonable than that in published literatures that all ignored the T≥T_m case. In order to show the validity of the modified model, the finite difference method is used to solve the model and different crystallization morphologies during the solidification process of isotactic polystyrene are obtained under different conditions. Numerical results show that the growth rate of the initial secondary arms is obviously increased as the anisotropy strength increases. But the anisotropy strength seems to have no apparent effect on the global growth rate. The whole growth process of the dendrite depends mainly upon the latent heat and the latent heat has a direct effect on the tip radius and tip velocity of side branches.     

Spin current and its heat effect in a multichannel quantum wire with Rashba spinben orbit coupling

Using the perturbation method, we theoretically study the spin current and its heat effect in a multichannel quantum wire with Rashba spin—orbit coupling. The heat generated by the spin current is calculated. With the increase of the width of the quantum wire, the spin current and the heat generated both exhibit period oscillations with equal amplitudes. When the quantum-channel number is doubled, the oscillation periods of the spin current and of the heat generated both decrease by a factor of 2. For the spin current j_s,xy, the amplitude increases with the decrease of the quantum channel; while the amplitude of the spin current j_s,yx remains the same. Therefore we conclude that the effect of the quantum-channel number on the spin current j_s,xy is greater than that on the spin current j_s,yx. The strength of the Rashba spin—orbit coupling is tunable by the gate voltage, and the gate voltage can be varied experimentally, which implies a new method of detecting the spin current. In addition, we can control the amplitude and the oscillation period of the spin current by controlling the number of the quantum channels. All these characteristics of the spin current will be very important for detecting and controlling the spin current, and especially for designing new spintronic devices in the future.     

Excited flux tube from q¯g hybrid mesons

In the framework of quark models, hybrid mesons are either seen as two-body qˉ systems with an excited flux tube connecting the quark to the antiquark or as three-body qˉg systems including a constituent gluon. In this work we show that, starting from the three-body wave function of the qˉg hybrid meson in which the gluonic degrees of freedom are averaged, the excited flux tube picture emerges as an equivalent qˉ potential. This equivalence between the excited flux tube and the constituent-gluon approach is confirmed for heavy hybrid mesons but, for the first time, it is shown to hold in the light sector too, provided the contribution of the quark dynamics is correctly taken into account.     

Deceleration of muonic hydrogen atoms in solid hydrogens

Results of recent calculations of cross-sections for muonic hydrogen atom scattering in solid hydrogen isotope targets are presented. The coherent parts of these cross-sections, namely, the elastic Bragg scattering and phonon coherent scattering, are calculated accurately for the first time. A fine structure of Bragg peaks is obtained in the case of Bravais fcc structure of hydrogen targets frozen rapidly at 3 K. The one-phonon coherent cross-section is estimated using the Debye approximation. The calculated differential cross-sections are used for Monte Carlo simulations of muonic atom diffusion and slowing down in solid hydrogens. Also is calculated the energy-dependent rate of resonant ddμ molecule formation in 3 K solid deuterium quantum crystal, using the Debye model and Van Hove's formalism of the response function. This rate is very different from that obtained for the 3 K gas model. The influence of dμ atom slowing down on the average ddμ formation rate is considered. It is shown that very slow dμ deceleration below 10 meV is important for explanation of experimental results. This revised version was published online in August 2006 with corrections to the Cover Date.     

Subthreshold ϕ-meson production and medium effects in proton-nucleus reactions

Within the spectral function approach, we study the direct production and decay via the dikaon (dimuon) channel of ϕ mesons in the interactions of 2.4-and 2.7-GeV protons with light and medium target nuclei. It is shown that the K ⁺ K ⁻ (μ⁺ μ⁻) invariant-mass distribution consists of the two components, which correspond to the ϕ decay “outside” and “inside” the target nucleus. The first (narrow) component has the free ϕ width, while the second (broad) component is distorted by the nuclear matter owing to resonance-nucleon scattering and a possible in-medium modification of the kaons and ρ meson at finite baryon density. The relative strength of the “inside” and “outside” components is analyzed in different scenarios for the ϕ width and momentum cut. It is demonstrated that the width of the resulting dimuon invariant-mass distribution on medium nuclei is larger than the free ϕ width by a factor of about 2 if the total ϕ in-medium width is used and the respective cutoff for the ϕ three-momentum is applied, whereas the resulting dikaon invariant-mass distribution has an insignificant sensitivity to the ϕ in-medium properties owing to the strong absorption of the K ⁻ in the surrounding nuclear matter. On the other hand, because of the distortion of the K ⁺ and K ⁻ on their way out of the target nucleus mainly due to the hadronic kaon potentials, the latter distribution is broadened and shifted to higher invariant masses, which means that the measurement of such broadening would give additional evidence for the modification of the kaon and antikaon properties in the nuclear medium. The text was submitted by the author in English.     

A new interpretation of an event attributed to a magnetic monopole

An alternate and a new interpretation is given for the event attributed to a magnetic monopole by Price and coworkers found in an emulsion plastic sandwich stack flown from Sioux City, Iowa, USA on 18 September 1973. The electron pick-up and stripping cross-sections of nuclei ofZ∼70–80 andv∼0.6–0.7c in Lexan polycarbonate are calculated using the formulae given by Nikolaev. It is shown that the corresponding mean free paths are of the order of thickness (∼250μ) of Lexan plastic sheets used by them. In such a case asnapshot of these processes is believed to have been observed in plastic sheets. Monte-Carlo simulations of the event have been made for three values of charges at the top of the main Lexan stack, namelyZ=83, 78 and 70 respectively. The event is thus interpreted as a cosmic ray nucleus ofZ=70–83 andv=0.6–0.7c losing and capturing electrons (mainly the latter) as it passes through the stack. The probability of the occurrence of such an event is estimated by several methods.     

Meson exchange hyperon-nucleon interaction based on correlated ππ/K¯ exchange

We present a new model for the hyperon-nucleon (ΛN , ΣN interaction, derived within the meson exchange framework. The model incorporates the standard one-boson exchanges of the lowest pseudoscalar and vector meson multiplets with coupling constants fixed by SU(6) flavor symmetry relations. As a new feature, the contribution in the scalar-isoscalar (σ sector is derived from a microscopic model of correlated ππ and Kˉ exchange. The same model is also used to constrain the interaction resulting from the vector-isovector (ρ exchange channel. Additional short-ranged ingredients of the model in the scalar-isovector (a₀) and scalar-isospin-1/2 (κ channels are likewise viewed as arising from meson-meson correlations but are treated phenomenologically. With this model a satisfactory reproduction of the available hyperon-nucleon data is achieved.     

Demonstration of the approximation of eliminating atomic excited populations in an atomben cavity system

Using the master equation approach to a V-type three-level atom inside a high-finesse single-mode cavity in the strong coupling condition, we demonstrate the approximation of eliminating populations of atomic excited states, which is widely used in the field of the atom-cavity systems [Hechenblaikner G, Gangl M, Horak P and Ritsch H 1998 Phys. Rev. A 58 3030]; Liu L W, Tan T and Xu Y 2008 J. Mod. Opt. 56 968; Cho J, Angelakis D G and Bose S 2008 Phys. Rev. A 78 062338. This is reflected in the deviation of the population δ, of which the value is 10^-3～10^-2. We further find the deviation of the dipole force and demonstrate that the deviation of atomic population will not notably affect the dipole force of the atom in the strong coupling condition. A relevant experimental case is also presented.     

Measurement of the differential and integral distribution of diffuse x-ray scattering intensity from defects in thin strained layers

Double-and triple-crystal diffractometry have been used to study structural perfection of a ∼1 μm-thick Ga_1−x In_xSb_1−y As_y epitaxial film (x=0.9, y=0.8) on GaSb. It is shown that scattering from samples of this system can be divided into coherent and diffuse. The arrangement of reciprocal-lattice points of the film and substrate in the two-dimensional intensity distribution for asymmetrical reflections argues for the absence of elastic-strain relaxation. No dislocation networks are formed, and the diffuse scattering is produced by Coulomb-type defects. Localization of diffuse scattering in reciprocal space suggests that these defects reside in the epitaxial film. The diffuse-scattering distribution in asymmetrical reflections is shown to be anomalous; namely, it extends in a direction parallel to the surface and is split into two maxima. Schemes have been proposed and realized for measuring integral distributions of diffracted intensity along the surface and perpendicular to it, and their potential for studying diffuse scattering from defects is explored. Fiz. Tverd. Tela (St. Petersburg) 39, 1188–1193 (July 1997)     

Field theory of finite-size effects in Ising-like systems

We propose a new perturbation approach to finitesize effects within the ⁴ field theory for a one-component order parameter with periodic boundary conditions. Our approach is applicable both above and belowT _c . Renormalization-group calculations of finite-size scaling functions in three dimensions are compared with new Monte Carlo data for theL×L×L Ising model withL=8, 16, 32. The field-theoretic predictions are in good overall agreement with the Monte Carlo data.Dedicated to Professor Herbert Wagner on the occasion of his 60th birthday     

Search for lepton-flavor-violating rare muon processes

A new approach to seeking three lepton-flavor-violating rare muon processes (μ → e conversion, μ → e + γ, and μ → 3e) on the basis of a single experimental facility is proposed. This approach makes it possible to improve the sensitivity level of relevant experiments by factors of 10⁵, 600, and 300 for, respectively, the first, the second, and the third of the above processes in relation to the existing experimental level. The approach is based on employing a pulsed proton beam and on combining a muon source and the detector part of the facility into a unified magnetic system featuring a nonuniform field. A new detector design involving separate units andmaking it possible to study all three muonic processes at a single facility that admits a simple rearrangement of the detectors used is discussed.     

Onset of the nonlinear dielectric response of glasses in the two-level system model

We have calculated the real part of the nonlinear dielectric susceptibility of amorphous insulators in the kHz range, by using the two-level system model and a nonperturbative numerical quantum approach. At low temperature T, it is first shown that the standard two-level model should lead to a decrease of when the measuring field E is raised, since raising E increases the population of the upper level and induces Rabi oscillations cancelling the ones induced from the ground level. This predicted E-induced decrease of is at odds with experiments. However, a better, though still not perfect, agreement with low-frequency experimental nonlinear data is recovered if, in our fully quantum simulations, interactions between defects are taken into account by a new relaxation rate whose efficiency increases as , as was proposed recently by Burin et al. [Phys. Rev. Lett. 86, 5616 (2001)]. In this approach, the behavior of at low T is mainly explained by the efficiency of this new relaxation channel. Since a quantitative understanding of glasses is still missing, we finally discuss experiments whose results should yield a refined understanding of this new relaxation mechanism: i) a completely new nonlinear behavior should be found for samples whose thickness is ≃ 10 nm; ii) a decrease of nonequilibrium effects should be found when E is increased. Received 19 September 2002 / Received in final form 4 December 2002 Published online 14 March 2003     

A new laser concept for isotopically selective analysis of noble gases

A new laser approach for the isotopically selective analysis of noble gases is presented. This approach uses noble gas atoms prepared in the 1s ⁵ metastable state. Hyperfine levels in the 1s ⁵ and 2p ⁹ states form two-level systems in Ne, Ar, Kr, and Xe which can be excited by a commercially available single-frequency laser system. Absorption of photons from such a laser, and the resulting momentum transfer, can be used to selectively deflect the desired isotope from a supersonic atomic beam into a detection area. Light from the same laser can then be used to selectively count atoms of the desired isotope using the photon-burst technique. Thus, enrichment and selective detection are accomplished with a single laser in a single pass through the apparatus.The problem of analyzing for⁸⁵Kr in a sample of noble gases extracted from the air is examined in detail. This is a stringent test of the selectivity of this approach because⁸⁵Kr has the same nuclear spin, and thus similar hyperfine splittings, as naturally occurring⁸³Kr. Calculations indicate that isotopic selectivity of the new approach is easily adequate to resolve⁸⁵Kr in a 10¹⁰ excess of⁸³Kr.     

A Method to Calculate Correlation Functions for β=1 Random Matrices of Odd Size

The calculation of correlation functions for β=1 random matrix ensembles, which can be carried out using Pfaffians, has the peculiar feature of requiring a separate calculation depending on the parity of the matrix size N. This same complication is present in the calculation of the correlations for the Ginibre Orthogonal Ensemble of real Gaussian matrices. In fact the methods used to compute the β=1, N odd, correlations break down in the case of N odd real Ginibre matrices, necessitating a new approach to both problems. The new approach taken in this work is to deduce the β=1, N odd correlations as limiting cases of their N even counterparts, when one of the particles is removed towards infinity. This method is shown to yield the correlations for N odd real Gaussian matrices. The work of P.J.F. was supported by the Australian Research Council, and A.M. was supported by an Australian Postgraduate Award.     

Antisymmetrization procedure of identical fermions states

An efficient procedure for antisymmetrization of an arbitrary system of identical fermions is presented. The approach is based on a simple enumeration scheme for antisymmetric A-particle states and an efficient algorithm for calculation of the coefficients of fractional parentage (CFPs) for a single j-shell with isospin. The developed approach is implemented in a new procedure for the calculation of the electric quadrupole moment matrix elements of light atomic nuclei in the isospin formalism.     

Quantum mechanics and relativity: attempt at a new start

The approach which led Louis de Broglie to the assertion, for particles with nonzero rest mass, of the two correlated relationsp =h/ andW =mc ² =hv, is reexamined. A modified approach is then developed. This leads to a set of mutually coherent new relations with respect to which de Broglie's relationsp =h/ andW =mc ² =hv appear as certain approximations. The mentioned set of new relations entails the prediction of specific effects which can be verified experimentally. If it is confirmed, this set of new relations might constitute the germ of a theory able to accomplish a veritable unification of relativity and microphysics.     

Kinetic component of the correlation energy density functional: a quantitative description from information theory

In the framework of information theory, a new method to determine T _c , the kinetic energy component of the correlation energy density functional for atoms, is presented. This approach is based on Shannon entropy and information energy that are obtained by fractional occupation probabilities of natural atomic orbitals. It is indicated that the calculated Shannon entropy using discrete probabilities is an increasing function while information energy is a decreasing function of the number of electrons. An expression is proposed with explicit dependence on the Shannon entropy or information energy and atomic number for the purpose. Applications of formulas for estimation of T _c values for neutral atoms up to Xe and their first positive and negative ions are then examined and validity of the proposed approach is numerically verified.     

Determination of thin film refractive index and thickness by means of film phase thickness

A new approach for determination of refractive index dispersion n(λ) (the real part of the complex refractive index) and thickness d of thin films of negligible absorption and weak dispersion is proposed. The calculation procedure is based on determination of the phase thickness of the film in the spectral region of measured transmittance data. All points of measured spectra are included in the calculations. Barium titanate thin films are investigated in the spectral region 0.38–0.78 μm and their n(λ) and d are calculated. The approach is validated using Swanepoel’s method and it is found to be applicable for relatively thin films when measured transmittance spectra have one minimum and one maximum only.