bluuebunny/crossref_metadata_2025 huggingface dataset:
Dyon–dyon bound states
Authors: Pandey V. P. , Chandola H. C. , Rajput B. S.
Published: April 2011

We investigate the structural symmetry between the generalized gravitational field associated with gravito-dyons and the generalized electromagnetic field associated with electro-dyons. We solve the Schrödinger and Dirac equations for generalized charge (mass) and show that the relative correction in the eigenvalues of dyons is quite large. We also demonstrate that the Bohr radius of dyonium (the bound state of dyons) is much smaller when compared with the atomic Bohr radius.
Input impedance of a 30–60–90° triangular patch antenna
Authors: Kyriacou George A. , Sahalos John N.
Published: April 2011

This paper deals with the analysis of a 30–60–90° triangular patch antenna. The geometrical optics method in which the reflected rays at the three edges interact in a constructive manner is used. Numerical results of the input impedance compared with experiments confirm the validity of the method.
Preequilibrium emission of multiparticles in α-induced reactions with 55Mn nucleus
Authors: Rizvi I. A. , Bhardwaj M. K. , Ansari M. Afzal , Chaubey A. K.
Published: April 2011

α-induced reactions on the target element Mn were investigated from 7 to 60 MeV, using the stacked-foil activation technique and the Ge(Li) γ-ray spectroscopy method. Six excitation functions for the reaction residues 58Co, 57Co, 56Co, 55Co, 54Mn, and 52gMn were measured, of which 55Mn (α,α3n) 52gMn was measured for the first time. The experimental data were compared with calculations considering equilibrium as well as preequilibrium reactions according to the geometry-dependent hybrid model of Blann (see Phys. Rev. Lett. 27, 337 (1971); 27, 700E (1971); 27, 1550E (1971)). The initial exciton number, n0 = 4, with different configurations was tested. It was found that the configuration (2n + 2p + oh) appears to give a good fit to the experimental data.
Complex force-constant dependence of elastic constants
Authors: Rafizadeh H. A.
Published: April 2011

Expressions for the inner and bare components of the elastic constants of crystalline solids are derived. The inner elastic constants are complex functions of the force constants and vanish only for centrosymmetric solids. Using a linear-chain model, the force-constant dependence of inner, bare, and total elastic constants is studied. The linear-chain model is also utilized in derivation of composition-dependent elastic constant equations. Single-parameter and two-parameter theoretical calculations are compared with the experimental composition-dependent Young's moduli of a number of metal–metalloid glasses.
Some interesting features of charged particles produced in high-energy hadron–emulsion collisions
Authors: Khushnood H. , Ansari A. R. , Irfan M. , Ali U.
Published: April 2011

The emission characteristics of secondary charged particles produced in 400 GeV proton–emulsion interactions were compared with those obtained at other energies. The results revealed that the angular distribution of grey particles does not depend on the nature and energy of the projectile. The dependence of the average multiplicity of the grey, black, shower, and heavily ionizing tracks on the mass of the target nucleus (A) and the nature and energy of the projectiles are also examined. The ratio of the valance quarks in pions (π−) and protons (p) was found to be almost equal to the ratio of the grey particles produced in π−–A and p–A collisions at the same energy. The values of the normalized moments of the multiplicity distributions of charged shower particles in different Nh intervals were found to be nearly the same. However, this value increased with increasing values of the moment index, K. Finally, the values of the normalized and central moments were almost equal for both p–p and p–A interactions.
Dependence of the response of the magnetosphere–ionosphere current systems on the preconditioning of the auroral oval and on the level of the solar–terrestrial interaction
Authors: Rostoker G. , Pascal F.
Published: April 2011

It is now well accepted that the impulse response time of the magnetosphere to sudden changes in the interplanetary medium is of the order of 2 h with the shape of the impulse response function approximating a Rayleigh function with a peak near 50 min. In a recent study, Bargatze et al. (J. Geophys. Res. 90, 6387 (1985)) examined the response of the magnetosphere for varying activity levels and found that the impulse response function has two well-defined peaks for moderate activity and a single broad peak for low and high activity levels. They explain the two peaks in the response function as the sequential contributions of the directly driven process and the unloading of stored magnetotail energy. In this paper, we ascribe to the magnetosphere–ionosphere system the bulk properties of self-inductance, capacitance, and resistance. We then proceed to construct an equivalent current system for the magnetosphere–ionosphere coupling process and study its response to changes in the cross polar cap potential drop. In particular, we permit the bulk electrical parameters to change in the manner expected as the input of energy from the solar wind modifies the magnetosphere–ionosphere system. We find that the double peak in the impulse response function identified by Bargatze et al. can be understood purely in terms of changes in the directly driven system without the need to introduce the effects of the unloading of stored energy in the magnetotail.
Measurement of anomalous dispersion in molecular iodine vapour by a simple interferometric method
Authors: Abraham R. G. , Booth J. L. , Dalby F W.
Published: April 2011

The index of refraction of iodine vapour was measured in regions of anomalous dispersion. These measurements were made using a Michelson interferometer illuminated by a tunable dye laser, and encompass 30 GHz regions centered near 17 408.3 and 17 565.1 cm−1. These regions contained several rovibrational lines of the [Formula: see text] transition, and at a vapour pressure of 0.28 Torr (1 Torr = 133.3 Pa) the index of refraction near these lines was found to vary by a few parts in 107.
Effect of pressure on the temperature of the displacive to order–disorder crossover associated with the structural phase transition in K2OsCl6
Authors: Armstrong Robin L. , Krupski Marcin , Su Sunyu
Published: April 2011

The 35Cl nuclear quadrupole resonance spectrum of K2OsCl6 is studied as a function of applied hydrostatic pressure in the temperature range bracketing the temperature of the rotational phase transition. The data suggest that the effect of increasing pressure is to increase the lattice dimensionality of the correlated rotational fluctuations that drive this phase transition.
Pseudopotential calculations of elastic scattering of electrons by helium atoms in the range 0–20 eV
Authors: Plenkiewicz B. , Plenkiewicz P. , Jay-Gerin J.-P.
Published: April 2011

Our earlier pseudopotential calculations on electrons colliding with argon and krypton are extended to consider the elastic electron–helium scattering system. In this paper, we present detailed results for phase shifts, differential, total, and momentum-transfer cross sections for this system for incident electron energies in the range from 0 to 20 eV. These agree very well with existing experimental data and with other theoretical calculations.
Collision-induced far infrared absorption in gaseous chlorine and chlorine–argon mixtures
Authors: Dagg I. R. , Anderson A. , Mooney M. C. , Joslin C. G. , Smith W. , Read L. A. A.
Published: April 2011

Collision-induced absorption is reported in Cl2 and Cl2–Ar gaseous mixtures at room temperature, in the spectral region below 120 cm−1. The results are analyzed according to existing theory, which incorporates estimates of the quadrupole and hexadecapole moments as well as relying on the accuracy of reported Lennard–Jones parameters. In addition, the spectral line shapes are compared with those calculated from information theory for which the theoretical expressions are given for multipole moments. The results for the mixtures are consistent with the generally accepted value of the quadrupole moment, 3.23(±.16) × 10−26 esu (3.23(+.16) Buckingham), and with a theoretical value of the hexadecapole moment, 31.4 × 10−42 esu. If these values of the moments are assumed, the Lennard–Jones parameters of Cl2, are estimated to be σ = 4.20 Å and ε/k = 307 K.
Geometric model for multiplicity distribution in nucleus–nucleus scattering
Authors: Kiang D. , Ochiai T. , Chan Y. P. , Young K.
Published: April 2011

The distribution in the multiplicity of charged particles produced in 0 + Cu and 0 + Au collisions is explained quantitatively in terms of the independent action of several tubes of nuclear matter, with each tube obeying universal Koba–Nielsen–Olsen scaling. With only one parameter, this model fits the observed distribution extremely well and reproduces the reduced second moments for collisions of several different nuclei pairs. Predictions for S + S and Pb + Pb collisions are presented.
An alternative mechanism for spin-forbidden photo-ionization of diatomic molecules and its rotation–electronic selection rules
Authors: Chiu Ying-Nan , Chiu Lue-Yung Chow
Published: April 2011

The spin-forbidden photo-ionization of diatomic molecules is proposed. Spin orbit interaction is invoked resulting in the correction and mixing of the wave functions of different multiplicities. The rotation–electronic selection rules given, but not proven, by Dixit and McKoy for Hund's case a based on the conventional mechanism of electric dipole transition (see Chem. Phys. Lett. 128, 49 (1986) are rederived and expressed in a different format. This new format permits the generalization of the selection rules to other photo-ionization transitions caused by the magnetic dipole, the electric quadrupole, and the two- and three-photon operators. These selection rules, which are for transitions from one specific rotational level of a given Kronig reflection symmetry to another, will help understand rotational branching and the dynamics of interaction in the excited state. They will also help in the selective preparation of well-defined rovibronic states in resonant-enhanced multi-photon ionization processes.
Hyperfine structure for some vacuum ultraviolet lines of Tl II and Tl III
Authors: Joshi Y. N. , Raassen A. J. J.
Published: April 2011

The thallium spectrum has been observed in the 1300–2000 Å region using sliding spark and triggered spark excitation sources. Hyperfine structure (hfs) splittings have been reported for 17 Tl II lines and 2 Tl III lines. This leads to the confirmation of the earlier analysis of Tl II in our region of observation. Revised level values for the levels of the 5d106s6p, 5d106s7s, 5d106s6d, and 5d106p2 configurations are also reported. A new value of the hfs constant A for 6s6p 3P1 in Tl II has been reported. Tentative values for the hfs constant A for 6s 2S1/2 and 6p 2P1/2,3/2 in Tl III have been suggested.
One dimensional nonlinear nonsteady state heat conduction I: general solution by perturbation theory
Authors: Hoff Heinrich
Published: April 2011

Taking into account the dependence of the heat capacity and heat conductivity on temperature, one obtains a nonlinear field equation of temperature. This nonlinear partial differential equation is resolved by perturbation theory for the particular case of a homogeneous system. The solution is checked by some criteria of control derived from thermostatics, from steady state transport, and from spatial symmetry. It forms the theoretical framework of nonlinear heat waves to be discussed in a future paper.
Processus non réactifs dans les collisions H2 + H(2s) aux énergies thermiques
Authors: Stern B.
Published: April 2011

Ab initio calculations of energy surfaces of the system [Formula: see text] corresponding to dissociation into H(2s) + H2 (X, 1Σg+) and H(2p0) + H2(X) are presented. For a thermal collision energy (0,064 eV), multistate close-coupling calculations are performed. In relation to experiments in progress, elastic and inelastic differential rotation cross sections are shown. For the quenching of H(2s) by H2:[Formula: see text]the cross section is obtained from an interference phenomenon between the elastic amplitudes associated to the two molecular states related to the entrance and exit channels, respectively. After criticizing the models used for the collision, which are valid only for small scattering angles, improvements are proposed in conclusion.[Journal translation]
A note on the determination of the nuclear charge density radius from the β decay between mirror nuclei
Authors: Parvez M. Sultan , Malik F. Bary
Published: April 2011

Using a trapezoidal charge density distribution the nuclear unit radius parameter, r0, and its surface thickness are deduced from the observed maximum positron kinetic energies in the β+ decay between two mirror nuclei. The deduced values are compatible with those obtained from the analyses of the electron scattering and μ-mesic atomic data.
Positron-impact ionization of atomic hydrogen in the distorted-wave polarized-orbital method
Authors: Mukherjee K. K. , Choudhury Keka Basu , Singh N. Ranjit , Mazumdar P. S. , Brajamani S.
Published: April 2011

Calculations are performed for the total cross sections for the positron-impact ionization of the ground state of atomic hydrogen, employing the distorted wave polarized orbital method. This explicitly takes into account the matrix elements arising from the distorted part of the target wave function and the effect of final-channel distortion in the incident-positron energy range 20.4–68 eV. The results are compared with available theoretical calculations.
Some more results from 340 GeV pion–emulsion and 400 GeV proton–emulsion interactions
Authors: Ahrar H.
Published: April 2011

Cluster characteristics in different regions of rapidity have been investigated in 340 GeV pion and 400 GeV proton–emulsion interactions. The data show that the strength of the correlation varies with the region in rapidity space. Some results on maximum rapidity-gap length, shower width distribution, position of the maximum rapidity in an event, multiplicity, and angular distributions of grey and black tracks etc. are also reported and discussed.
The capture γ-ray spectrum of Mg
Authors: Prestwich W. V. , Kennett T. J.
Published: April 2011

The capture γ rays of natural Mg are analyzed. The results indicate neutron separation energies of 7333.57 ± 0.07, 11 093.09 ± 0.08, and 6443.29 ± 0.12 keV for the 25Mg, 26Mg, and 27Mg products. From the primary intensities estimates of 51.5 ± 2.5 and 201 ± 9 mb for the 24Mg and 25Mg capture cross sections are deduced. Refined level energies for the three product isotopes are calculated and compared with previous results. Direct capture effects for electric and magnetic dipole and electric quadrupole transitions are discussed.
The (5d10 + 5d96s) – 5d96p transitions in Tl IV, Pb V, and Bi VI
Authors: Joshi Y. N. , Raassen A. J. J. , Valk A. A. Van der
Published: April 2011

The spectra of thallium, lead, and bismuth were photographed in the region 600–2000 Å using sliding spark and triggered spark sources. The (5d10 + 5d96s)–5d96p transitions in Tl IV, Pb V, and Bi VI were investigated. Earlier level values were revised and new lines were classified. Hyperfine structure splittings were observed for many lines in Tl IV and Bi VI. Least squares fitted calculations were done for each spectra. The deviations between the calculated and observed level values showed that parametric descriptions using only the spin-orbit magnetic interaction parameter to describe magnetic effects is not sufficient in the 5d-shell spectra.
Operator regularization and composite operators
Authors: McKeon D. G. C.
Published: April 2011

We demonstrate how operator regularization can be used to compute radiative corrections to Green's functions involving composite operators. No divergences are encountered and no symmetry-breaking regulating parameter need be introduced into the initial Lagrangian. We demonstrate the technique to one-loop order by considering operators of dimension four in the [Formula: see text] model and the operator [Formula: see text] in an axial model. Anomalous dimensions of these operators are determined by considering finite Green's functions. There is no need to define "oversubtracted" operators to maintain linearity, as is the case when one uses BPH subtraction, nor is there an ambiguity between the trace of [Formula: see text] and [Formula: see text], as occurs in dimensional regularization. Quantities such as γ5, εμνλσ, and εμν (which are well-defined only in an integer number of dimensions) are treated unambiguously as we never alter the dimensionality of the problem.
"Universality" of Gaussian orthogonal ensemble fluctuations: the two-body random ensemble and shell model spectra
Authors: Laberge Gaetan J. H. , Haq Rizwan U.
Published: April 2011

Starting from an appropriate decomposition of the level density into an average and fluctuating part, we studied the energy level fluctuations of an ensemble defined by two-body random Hamiltonians. A detailed analysis of several spectrally averaged fluctuation measures shows close agreement with the predictions of the Gaussian orthogonal ensemble (GOE). This confirms earlier indications that, except for noninteracting particles, fluctuation measures are insensitive to the rank of the interaction. Further, analysis of spectra obtained from realistic nuclear interactions agrees well with the GOE indicating that specific properties of the Hamiltonian have little or no influence on fluctuations. These results, therefore, strengthen our belief in the "universality" of GOE fluctuations.
Diode laser spectroscopy of the atmospheric oxygen band
Authors: Kanamori Hideto , Momona Morihisa , Sakurai Katsumi
Published: April 2011

The atmospheric oxygen band due to magnetic dipole transitions was studied by a diode laser absorption spectroscopy combined with a Zeeman modulation technique. The high-resolution spectrum of the 0–0 band was observed with Doppler-limited resolution and compared with a previous spectrograph measurement. The Zeeman effect at low magnetic field was investigated by the Zeeman line profiles. It was found that the second-order Zeeman effect was observable in the F2 transition of the [Formula: see text] state with magnetic field as low as 150 G.
Les pics latéraux dans les filtres composites
Authors: Métioui A.
Published: April 2011

In this paper, we present some theoretical considerations of the apparition of sidelobes in the pattern recognition process when use is made of the composite filter of Caulfield and Maloney.
Inclusion of off-normal incidence data in a low-energy electron diffraction crystallographic analysis for the Cu(100)-(2 × 2)-S surface structure
Authors: Zeng H. C. , McFarlane R. A. , Mitchell K. A. R.
Published: April 2011

A low-energy electron diffraction (LEED) crystallographic analysis has been undertaken to assess the lateral and vertical relaxations for the Cu(100)-(2 × 2)-S surface structure. The study uses five normal-incidence beams and seven beams with an off-normal direction for a polar angle of incidence equal to 8°. Both lateral and vertical relaxations in the copper structure are small (0.03 Å or less) compared with the structure in bulk copper, but the senses are unchanged from the recent normal-incidence analysis (H. C. Zeng, R. A. McFarlane, and K. A. R. Mitchell, Phys. Rev. B, 39, 8000 (1989)). The new LEED-determined S—Cu bond length is 2.23 ± 0.06 Å, while the S to topmost Cu interlayer spacing is 1.28 ± 0.03 Å.
Degenerate fermion and Wilson loops in 1 + 1 dimensions
Authors: Shiraishi Kiyoshi
Published: April 2011

We investigate the effect of finite fermion density on symmetry breaking by Wilson loops in (1 + 1) dimensions. We find the breaking and restoration of symmetry at finite density in models with SU(2) and SU(3) gauge symmetries, in the presence of the adjoint fermions. The transition can occur at a finite density of fermions, regardless of the periodic or antiperiodic boundary condition of the fermion field; this is in contrast to the finite-temperature case examined by Ho and Hosotani (IASSNS-HEP preprint 88/48) where the boundary condition of fractional twist is essential to the occurrence of the phase transition.
Calcul des éléments dipolaires et quadrupolaires de la matrice de transition moléculaire dans Na2
Authors: Hussein K. , Babaky O.
Published: April 2011

In this paper, we study a calculation of the transition elements [Formula: see text] between electronic states of the diatomic molecules Na2. We show the necessary selection rules for the determination of these operators by a method of analytical integration on the variable [Formula: see text], combined with a numerical integration to fifth order. The values found by this simple method of calculation are very reasonable and show that the important transitions [Formula: see text], [Formula: see text]; and [Formula: see text] of the dimer Na2 are dipolar. [Traduit par la revue]
Electromagnetic scattering by a system of two parallel dielectric prolate spheroids
Authors: Cooray M. F. R. , Ciric I. R. , Sinha B. P.
Published: April 2011

An exact solution to the problem of scattering of a plane electromagnetic wave by two dielectric prolate spheroids with parallel major axes is obtained by expanding the incident, scattered, and transmitted electric and magnetic fields in terms of an appropriate set of vector spheroidal eigenfunctions. The incident wave is considered to be a monochromatic, uniform plane electromagnetic wave of arbitrary polarization and angle of incidence. The boundary conditions are imposed by expressing the electromagnetic field scattered by one spheroid in terms of the spheroidal coordinates attached to the other, using the translational addition theorems for vector spheroidal wave functions. The column matrix of the total transmitted and scattered field-expansion coefficients is equal to the product of a square matrix, which is independent of the direction and polarization of the incident wave, and the column matrix of the known incident field-expansion coefficients. The solution of the associated set of algebraic equations gives the unknown transmitted and scattered field-expansion coefficients. Even though the problem is formulated in general, the numerical results are presented for the bistatic and backscattering cross sections of two lossless prolate spheroids with various axial ratios and center-to-center distances.
Le problème cosmologique dans les variétés de Kaluza–Klein multiconnexes
Authors: Gauthier Claude , Gravel Pierre
Published: April 2011

In unified field theories of the Kaluza–Klein type, we propose a new axiom to explain the inobservability of the superior space. Based on the multiconnectivity of the latter, this axiom yields a solution to the classical cosmological problem.
The Yukawa interaction in the Skyrme model
Authors: Mobed Nader , Zhu Xiquan , Khanna Faquir C.
Published: April 2011

The complete form of Yukawa coupling terms, in the pion–Skyrmion system, for a rotating and moving Skyrmion is given. It is shown that pions couple linearly to the space component of the axial-vector current in addition to coupling to the time component. When both interactions are taken into account, the pionic decay width of Δ(1232) is modified by a significant amount.
Scattering by a separable potential in one dimension
Authors: Muga J. G. , Snider R. F.
Published: April 2011

The scattering by a separable potential in one dimension is described by means of explicit expressions for the reflectance coefficient, phase shift, and excess density. Resonances, bound and virtual states are analyzed in the light of the position of the poles of the resolvent, and a physical consequence of the spurious poles of the S matrix is indicated. Deviations from the usual partial wave analysis in three dimensions, especially a modification of Levinson's theorem, are also studied. It is shown that at very low energies the slope of the phase shift is not always a valid indicator of the excess density in the interaction region.
A numerical solution for conducting bodies of arbitrary shape
Authors: Moheb H. , Shafai L.
Published: April 2011

An efficient numerical technique based on a Fourier expansion of the surface current is developed to study the electromagnetic scattering from three-dimensional geometries of arbitrary shape. In this method, the discrete domain representing the structure surface is geometrically represented by two orthogonal contours. One is selected along the intersection of the x–z plane with the object's surface, and the other along the corresponding one in the x–y plane. Entire domain basis functions are selected for the current component in the x–y plane, and subdomain linear basis functions are used to represent the other current component. The method of moments is used to solve the problem numerically. The technique is then applied to study the scattering from discrete surfaces such as squares and rectangles, to compare them with those of the coordinate-transformation technique developed earlier. The behavior of the solutions with the number of modes is investigated to determine their coupling.
Quantum-interference effects in some fields
Authors: Krori K. D. , Borgohain P. , Barua Madhumita , Das Kanika
Published: April 2011

In this paper, we derive quantum-interference effects for (a) nonspinning particles in Einstein and Yang–Mills fields and (b) spinning particles in Einstein and Einstein–Cartan fields.
Equation of motion for a charged bound particle in a zero-point field
Authors: Battezzati M.
Published: April 2011

A method previously proposed by the same author, of solving the equations of motion in the presence of friction and an external stochastic force, is applied to the nonrelativistic Dirac equation for a charged bound pointlike particle in a black-body radiation field. It separates the particle velocity field, under the assumtion of stationarity, into a position-dependent component and a randomly fluctuating component depending mainly upon the time. This description of the possible stationary states of the bound particle in the random force field is taken as a starting point for establishing a diffusion equation in configuration space. Since we identify the first component with the drift velocity, we show that it must be the solution to a modified Hamilton–Jacobi equation by using a term that is the counterpart of the quantum modification to the same equation, which has as a first approximation exactly the same form. This term gives results proportional to the diffusion coefficient and, thereby, to the spectral density of the external random force. The diffusion equation that is obtained has complex coefficients and therefore it defines a probability density for the complex values of the variable coordinate. We propose an interpretation of this probability density, based on a specific example.
Laser-induced fluorescence and excitation spectra of the ZnH molecule
Authors: Kedzierski W. , Supronowicz J. , Atkinson J. B. , Krause L.
Published: April 2011

Radiative transitions between the A2Π and X2Σ+ states of the ZnH molecule were induced using pump-and-probe methods of laser spectroscopy and resulted in the observation of several fluorescence and excitation bands with rotational structure. A time-evolution study of the fluorescence yielded the radiative lifetime τ0 = 47 ± 3 ns for the A2Π state; the cross section for quenching the A2Π, ν = 0 state by Zn collisions was estimated to be (2.4 ± 0.3) × 10−15 cm2. We also concluded that the ground-state ZnH molecule is a transient species that exists for approximately 10 μs.
A nonlinear gauge-invariant field theory of elementary particles
Authors: Sharman P. H. , Cooperstock F. I.
Published: April 2011

The field theory of Cooperstock and Rosen (Int. J. Theor. Phys. 28, 423 (1989)), which modelled leptons, is enlarged to encompass the two known quark families. The singularity-free field theory constructs the particles in solitonlike structures via the nonlinear interaction of three scalar fields and the electromagnetic field. The theory predicts particle sizes that are consistent with experiment.
Cross sections for the 93Nb(n,2n)92mNb reaction
Authors: Santry D. C. , Werner R. D.
Published: April 2011

The cross section of the 93Nb(n,2n)92mNb reaction has been studied by use of the activation method from the threshold energy of 8.8–19.8 MeV. Measurements are relative to the known cross-section values for the reactions H(n,n)H, 32S(n,p)32p, and 27Al(n,α)24Na. The cross-section value increases smoothly with energy and reaches a maximum value of 444 ± 18 mb at about 14.5 MeV then decreases to values of 293 ± 14 mb at 19.8 MeV. An effective cross-section value for a fission neutron spectrum calculated from the results is 0.321 ± 0.019 mb. The activation of Nb as a transfer standard for 14 MeV neutrons is discussed.
The dynamics of a honeycomb array of domain walls as a network of interconnected strings
Authors: Shrimpton Neil D. , Joós Béla
Published: April 2011

A honeycomb array of domain walls such as is found in incommensurate phases of rare-gas monolayers on graphite is shown to vibrate as an interconnected network of strings. The vibrational modes of the network are determined by the vertices, which provide the boundary conditions for the domain-wall segments. The dynamical matrix is constructed and solved for the normal modes. The krypton on graphite system is used as a test to the theory. A Hamiltonian is constructed for the domain-wall network and the amplitude of the lowest energy mode, the breathing mode, is discussed.
Green's function approach to propagation in fibres of arbitrary cross section
Authors: Bhattacharjee S. , Menon V. J. , Dey K. K.
Published: April 2011

An attempt has been made to obtain a formally exact solution, based on Green's function of the scalar wave equation for step-index fibres of arbitrary cross-sectional shape. The wave functions in the core and cladding are expanded in a series of basis functions (appropriate to cylindrical coordinates), and the expansion coefficients along with the characteristic equation of the problem are derived in a matrix notation. Compared with the earlier similar treatments of the problems, the present formalism is very general in the sense that it does not assume any special symmetry property of the cross-sectional curve or of the underlying solutions. The theory is applied to fibres that are only slightly deformed about a circular shape. Explicit algebraic and (or) numerical results are obtained for the allowed propagation constants, fields, and the group delay of a few low-ordered modes.
Pair production of leptoquark scalars in hadron colliders
Authors: Montigny Marc de , Marleau Luc
Published: April 2011

We estimate soft-gluon corrections generated by π2 terms in the production of pairs of scalar leptoquarks in hadron collisions. These particles appear naturally in a superstring inspred E6 model and can be produced through quark–antiquark annihilation and gluon fusion with or without Yukawa interactions.
Zeta-function regularization of quantum field theory
Authors: Shiekh A. Y.
Published: April 2011

Analytic continuation leads to the finite renormalization of a quantum field theory. This is illustrated in a determination of the two loop renormalization group functions for [Formula: see text] in four dimensions.
A magnetized object in Kaluza–Klein theory
Authors: Krori K. D. , Sarmah J. C.
Published: April 2011

In this paper, we present a study of the stable equatorial (θ = π/2) and polar [Formula: see text] trajectories of neutral or charged test particles around a magnetized object in five-dimensional Kaluza–Klein theory. We also show how the nature of these trajectories changes with the variation of the angular momentum of the test particles and with the magnetic-field parameter. We point out that the Gaussian curvature tends to infinity at the Matos surface (defined in the text). A comparison is also made between four-dimensional and five-dimensional studies for equatorial and polar trajectories.
The Arctic ozone crater in 1989
Authors: Evans W. F. J. , Walker A. E. , Bunn F. E.
Published: April 2011

The presence of a thinned area or craterlike feature in the Arctic polar ozone layer during March, 1986 has been reported previously (Can. J. Phys. 67, 161 (1989)). In this paper the morphology of the reappearance of the crater from January to March, 1989 is described. It appeared over northern Europe in late January and moved over western Canada in late February. The minimum value of ozone in the crater floor had fallen from 300 DU (1 Dobson unit (DU) = 0.01 mm) in 1979 to a new low of less than 200 DU in 1989, which is similar to the thinned total ozone columns observed within the Antarctic ozone hole. Analysis of the available total ozone mapping spectrometer ozone measurements indicates that the crater could be explained by a combination of two mechanisms; a chemical process, which depleted the ozone concentrations at altitudes in the 14–22 km region, and a transport process, which shifted the altitude distribution of ozone upwards such as a vertical circulation cell. Although the Arctic ozone crater is similar in several aspects to the Antarctic ozone hole, there remain several differences; the issue is whether the crater and the hole are manifestations of the same phenomenon. We consider that the Arctic ozone crater is mainly produced by dynamic redistribution driven by tropospheric circulation features.
Neutrino bumpy waves
Authors: Hillion Pierre
Published: April 2011

Starting with the Pauli equation we obtain new spinor waves that appear as solutions of a boundary value problem with data on the wave fronts. For an observer moving with a wave front the transverse structure is invariant, and because of this we call these new solutions, neutrino bumpy waves.
Analysis of Gaussian cavity-backed slot radiators
Authors: Hadidi A. , Hamid M.
Published: April 2011

The problem of a slot radiator backed by a Gaussian cavity is analyzed. The fields in the cavity are expressed in terms of Gauss–Hermite functions whose orthogonality property is used to obtain the expansion coefficients. An integral equation is derived for the tangential electric field in the slot aperture and entire-domain basis and testing functions are utilized in its numerical evaluation. The restrictions imposed on the cavity dimensions by the wave beam assumptions are discussed and the equation for the surface of the cavity backwall is given. Finally, typical numerical results for the voltage distribution along the slot aperture are presented for the cases of symmetric and skew-symmetric excitations.
Operator regularization and massive Yang–Mills theory
Authors: Culumovic L. , McKeon D. G. C. , Sherry T. N.
Published: April 2011

Operator regularization has proved to be a practical method for computing finite, symmetry preserving Green's functions to arbitrary order in perturbation theory. This finiteness has been shown to persist in such nonrenormalizable theories as [Formula: see text] and quantum gravity; in this paper we apply the technique to massive gauge theories. The mass for the vector particle is inserted by hand using the Stueckleberg–Kunimasa–Goto mechanism; no degree of freedom associated with the Higgs scalar is present in the initial Lagrangian. Several one-loop calculations serve to illustrate that no divergences ever arise in this theory if one uses operator regularization. The one-loop effective action is examined in both 4 and n = (4 − ε) dimensions. The result is finite in 4 dimensions and in (4 − ε) dimensions has the pole structure at ε = 0 found by Kafiev. In four dimensions, we find that, in contrast to the case of renormalizable theories, radiatively induced interactions occur with coefficients depending on log (p2/μ2). Consequently μ2 is no longer an arbitrary parameter but must be fixed experimentally.
Multiple scattering by a linear array of conducting spheres
Authors: Hamid A-K. , Ciric I. R. , Hamid M.
Published: April 2011

The problem of multiple scattering of a plane electromagnetic wave incident on N closely spaced perfectly conducting spheres is solved analytically by expanding the incident and scattering fields in terms of an appropriate set of vector spherical wave functions. To impose the boundary conditions, the scattered field from one sphere is expressed in coordinate systems attached to the others by using the translation addition theorem. An approximate solution is obtained to solve for the scattering by N small spheres. Numerical results for the normalized backscattering and bistatic cross sections for systems of spheres show that the agreement between the analytic and approximate solutions is better for larger electrical distances between neighbouring spheres.
Operator regularization and the chiral anomaly
Authors: Culumovic L. , McKeon D. G. C.
Published: April 2011

Operator regularization is used to compute anomalies in axial gauge theories to one- and two-loop order. To one-loop order, we consider the decay of a U(1) axial current into two, three, and four SU(N) vector currents. This is done first by directly computing the relevant Green functions, and then by a functional approach. The one-loop anomaly is found to be proportional to trF*F. We note that the quadrilinear term in this expression is zero. The Schwinger expansion, employed in operator regularization to generate Green functions, is then used to derive the Schwinger–de Witt WKB (Wentzel–Kramers–Brillouin) expansion of the heat kernel, recovering the known diagonal elements and also giving the previously unknown off-diagonal elements. For the case of a constant background electromagnetic field, these off-diagonal terms can also be obtained from an exact expression for the heat kernel given by Schwinger. We then use this result, in conjunction with the functional technique originally introduced in one-loop calculations, to compute exactly the amplitude for the decay of the U(1) axial current into both U(1) and O(3) constant gauge fields to two-loop order. With the appropriate choice of mass scale parameters, a vanishing result is obtained, in agreement with the Adler–Bardeen result.
Résonance cyclotronique dans une jonction polarisée
Authors: Ammari M. , Gire A. , Lomaglio G. , Théobald J. G. , Blanc F. , Fanguin R. , Raoult G.
Published: April 2011

To verify some of the hypotheses used in previous papers (F. Blanc et al. Can. J. Phys. 66, 11 (1988); F. Blanc et al. Can. J. Phys. 67, 148 (1989); A. Gire et al. 68, 190 (1990)), we experimented with cyclotron resonance in polarized junctions. The polarization of the junction was used to modulate and detect the resonance. The experiment allows to determine the effective mass of charge carriers responsible for the radiofrequency susceptibility observed previously. [Traduit par la revue]
Far infrared absorption of the gaseous CH4–Ar mixture
Authors: Dore P. , Filabozzi A.
Published: April 2011

We present the first measurements of the rototranslational absorption spectrum of the CH4–Ar gaseous system in the far infrared region 40–600 cm−1. Measurements were made at 296, 243, and 195 K at densities as low as possible; the binary absorption spectrum of the CH4–Ar pair was then obtained. We performed a line-shape analysis of these spectra following the procedure previously introduced for pure methane. We find that the experimental data can be described at high frequencies by using ab initio values of the octopole and hexadecapole multipole moments and anisotropic overlap intensities very close to those used for pure methane. At low frequencies, the computed spectrum is significantly lower than the experimental data at any temperature. We thus include in our analysis a low-frequency spectral contribution associated with the isotropic overlap induction mechanism. Good fits of the experimental data are then obtain at each temperature over all the spectral range.
On the formation of secondary shocks in a self-similar magnetogasdynamic flow
Authors: Kumar A. , Sharma V. D. , Pandey B. D.
Published: April 2011

The problem of a self-similar flow behind a cylindrical shock wave, produced by the sudden release of a finite amount of energy per unit length along an axis of infinite extent in a plasma permeated by a transverse magnetic field, has been solved exactly for the specific heat ratio γ = 2. This value for the specific heat ratio γ is known to approximate the plasma state in a uniform magnetic field. We used the singular surface theory to study the propagation of a weak discontinuity in this self-similar flow, and calculated the critical time for a shock formation. We find that the appearance of a secondary shock cannot be ignored if the amplitude of the initial discontinuity satisfies appropriate conditions. The condition of the nonimpact between a weak discontinuity and the primary shock has also been discussed.
Improvement of the convergence of the exponential perturbation theory in the Schrödinger representation by dividing the time interval
Authors: Popescu V. A. , Popescu I. M.
Published: April 2011

It is shown that by dividing the time interval an increase in the convergence of the exponential perturbation theory in the Schrödinger representation arises. Comparison with the interaction picture is made.
Application of the charged-hard-sphere model to liquid transition metals
Authors: Rao R. V. Gopala , Venkatesh R.
Published: April 2011

The structure factors of the transition metals Fe, Co, and Ni were evaluated in the charged-sphere model. The weak coupling of the electrons and the ions were taken into consideration through the use of the Ashcroft empty-core pseudopotential model. A parameter Γ was introduced to take into consideration the effective charge due to ions on electrons. The agreement between theory and experiment was found to be excellent.
End effects in the magnetic field of free electron lasers with sheet electron beams
Authors: Pocobelli G.
Published: April 2011

We calculate the magnetic field of a free-electron-laser's wiggler of a recent design (Granatstein et al. Appl. Phys. Lett. 74, 643 (1985)) using sheet electron beams. We did not assume periodic boundary conditions, as was done in their work, and we obtained analytical expressions in two of the three space variables. We found various irregularities in the field behavior that were dependent on the size of the wiggler in the x direction (parallel to the beam's wide size), and that increased up to a width an order of magnitude greater than the height of the beam channel. These irregularities had been observed in field measurements. A method consisting of making the end magnets thinner worked effectively to reduce the irregularities. We also studied a similar magnetic configuration with free and independent currents and no magnets, and added the additional degree of freedom of programming the currents to further reduce the irregularities.
Ultraviolet absorption in proton-irradiated solid deuterium
Authors: Forrest J. A. , Hunt J. L. , Brooks R. L.
Published: April 2011

A broad absorption near a wavelength of 350 nm in proton-irradiated solid deuterium at 4.2 K has been measured. The absorption is caused by the resonant detrapping of localized electrons from their quantum bubbles. The growth and decay of the absorption with onset and termination of the proton beam is shown to be consistent with similar timing measurements on other spectroscopic features associated with the localized electrons. A simple square-well potential model is used to estimate the depth of the well and the size of the electron bubbles.
Low-energy pion photoproduction from p-shell nuclei
Authors: Bennhold C. , Tiator L. , Wright L. E.
Published: April 2011

Low-energy pion photoproduction off 6Li, 10B, and 14N has been reinvestigated in a DWIA framework that includes a number of improvements neglected in previous analyses. The production operator is based on Feynman diagrams and includes correction terms of order p2/M2 and higher. An s-channel delta resonance term is included with both longitudinal and transverse electromagnetic couplings. Rather than using on harmonic oscillator for the nucleon orbitals we employ Woods–Saxon wave functions that have been adjusted to fit electron-scattering form factors and single-particle binding energies. Furthermore, we include the Coulomb potential without approximation in our momentum-space approach. Using more realistic wave functions and including corrections to the production amplitude that have been neglected before leads to considerable improvement in the case of 10B and 14N when compared with existing data. The Coulomb effects are shown to change the cross section by about 30% close to threshold but are negligible at higher energies.
Temperature dependence of the thermal diffuse X-ray scattering from sodium single crystals
Authors: Mayr W. , Fritsch G. , Lüscher E.
Published: April 2011

We report on experimental results for the thermal diffuse X-ray-scattering cross section from Na single crystals. Data are presented for the [100], [110], and [111] directions taken in the temperature range from 38 K to the melting point. In addition we present a numerical calculation of the harmonic diffuse-scattering cross section including all orders of multiphonon contributions using a realistic phonon-dispersion relation. The results of this model are compared with a simpler approximation for the higher order multiphonon terms. The differences between the calculations and the experimental data show a distinct asymmetrical behaviour with respect to the reciprocal lattice points. Owing to this fact and their temperature dependence they can be related to anharmonic scattering. The contributions of the four lowest order terms are derived from the data. The lowest order antisymmetric contribution agrees quite well with available theoretical calculations.
Onset of diffraction-induced pulse deformation in transient-stimulated Raman scattering
Authors: Teichmann J. , Roussel A. , Ethier S. , Teichmann M.
Published: April 2011

The copropagation of ultrashort pump, Stokes, and anti-Stokes pulses is studied on the basis of a simple analytical model, taking into account the diffraction effects. The onset of transversal phase variations, radial energy flow, and pulse degradation is demonstrated for different initial pump profiles and different Fresnel numbers.
Low-lying states in 97Mo and 101Mo by (t, d) and (d, p) reactions on the neighbouring molybdenum isotopes
Authors: Habib E. E. , Cameron J. A. , Din G. U. , Janzen V. , Schubank R.
Published: April 2011

The values of spins, parities, and spectroscopic factors for neutron transfer have been determined for many low-lying states in 97Mo and 101Mo by a study of the (t, d) and (d, p) reactions on the neighbouring even-mass isotopes. Eighteen new values of Jπ have been obtained for these nuclei. Values of the fullness and emptiness parameters V2 and U2 have been suggested for the 3s1/2 and 2d5/2 orbitals in 100Mo. (Nuclear structure 97Mo, 101Mo, measured J,π, and spectroscopic factors for states up to ~2.0 MeV using (d, p) and (t, d) reactions.)
The s–d quark weak-transition, operator regularization and the kaon ΔI = (1/2) rule
Authors: Elias V. , McKeon D. G. C. , Scadron M. D.
Published: April 2011

We first show that the s–d quark self energy Σsd is gauge invariant through order (ms–md)/mc. Next we use operator regularization to renormalize Σsd in a left-handed (and not mass-shell) manner. Then we nonperturbatively hadronize Σsd for kaon decays, consistent with chiral symmetry and pion partially conserved axial-current considerations. The agreement with the observed nonleptonic kaon decays is excellent. Finally, we suggest that previous "no-go" theorems do not pertain to Σsd and to our hadron predictions.
On the weak-interaction contribution to the anomalous magnetic moments of the muon and the electron
Authors: Samuel Kenneth B. , Samuel Mark A.
Published: April 2011

The weak-interaction contribution to the anomalous magnetic moments of the muon (aμ) and the electron (ae), (a = (g − 2)/2) are computed as a function of the (unknown) Higgs-boson mass (mH). For large mH > 10 GeV), aμ = 1.81 × 10−9 and ae = 4.21 × 10−14.