Continuity equation constraint in the transverse quadrupole electric-type form factors

The analysis of nuclear convection-current contributions to the transverseE 2 isoscalar and isovector form factors in¹²C initiated by Flanz et al. has been extended. It is shown that the continuity equation of the nuclear electromagnetic current provides the constraint needed to explain the behaviour of the form factors studied in the range 0<q<2fm^–1.     

Electron impact single ionization of mono- and di-positive ions

The electron impact ionization cross-sections of mono- and di-positive ionic targets are calculated using a second version of the modified binary-encounter-dipole (MBED) model, previously reported [M A Uddinet al, J. Phys. B37, 1909 (2004)]. The present version differs from the previous one in the scale factor of the Burgess denominator and is applicable to targets with chargesq = 1 and 2. The MBED in the present form is found to work well for 11 ionic targets ranging from Be⁺ to K⁺ and complements its previous version valid for targets withq s> 2     

A numerical study of the formation of magnetisation plateaus in quasi one-dimensional spin-1/2 Heisenberg models

We study the magnetisation process of the one-dimensional spin-1/2 antiferromagnetic Heisenberg model with modulated couplings over j=1,2,3sites. It turns out that the evolution of magnetisation plateaus depends on j and on the wave number q of the modulation according to the rule of Oshikawa et al. A mapping of two- and three-leg zig-zag ladders on one-dimensional systems with modulated couplings yields predictions for the occurrence of magnetization plateaus. The latter are tested by numerical computations with the DMRG algorithm. Received 14 October 1999 and Received in final form 6 January 2000     

Kl3 form factors at order p of chiral perturbation theory

This paper describes the calculation of the semileptonic K_l3 decay form factors at order p⁶ of chiral perturbation theory, which is the next-to-leading order correction to the well-known p⁴ result achieved by Gasser and Leutwyler. At order p⁶ the chiral expansion contains one- and two-loop diagrams which are discussed in detail. The irreducible two-loop graphs of the sunset topology are calculated numerically. In addition, the chiral Lagrangian produces direct couplings with the W bosons. Due to these unknown couplings, one can always add linear terms in q² to the predictions of the form factor f _- (q ² ). For the form factor f ₊ (q ² ), this ambiguity involves even quadratic terms. Making use of the fact that the pion electromagnetic form factor involves the same q⁴ counterterm, the q⁴ ambiguity can be resolved. Apart from the possibility of adding an arbitrary linear term in q² our calculation shows that chiral perturbation theory converges very well in this application, as the corrections are small. Comparing the predictions of chiral perturbation theory with the recent CPLEAR data, it is seen that the experimental form factor f ₊ (q ² ) is well described by a linear fit, but that the slope is smaller by about 2 standard deviations than the prediction. The unavoidable q² counterterm of the corrections allows one to bring the predictions of chiral perturbation theory into perfect agreement with experiment. Received: 8 January 2002 / Revised version: 27 March 2002 / Published online: 20 September 2002 RID="*" ID="*" Now at Fraunhofer Gesellschaft, Institute for Algorithms and Scientific Computing (SCAI), Schloss Birlinghoven, D-53754 Sankt Augustin, Germany, e-mail: peter.post@scai.fraunhofer.de RID="**"     

Sea Level Muon Spectrum Derived from the All Particle Primary Spectrum of GRIGOROV et al.

The all particle primary spectrum of GRIGOROV et al. surveyed by HILLAS has been fitted by a power law fit of the form I_{all particle}(>E) = 1.3 E^?1.65 (cm² s sr)^?1 where E is the energy in GeV/nucleus. Using our recently determined conversion factor for protonnuclei flux ratio of equal energies the primary proton spectrum has been calculated and the result agrees with the Goddard Space Flight Centre primary proton spectrum data satisfactorily. The primary nucleon spectrum has also been calculated and follows the form N_nucleons(E) dE = 2.664 E^?2.75 dE (cm² s sr GeV/nucleon)^?1. Using this primary nucleon spectrum as the source of hadrons and accelerator data for various inclusive reactions viz. used for the estimation of hadronic energy moments in the frame work of FEYNMAN- Scaling, the differential meson spectra have been estimated. The meson atmospheric diffusion equation after Bugaev et al. has been considered for the derivation of sea level muon spectrum. The magnetic spectrograph data of Allkofer et al., Ayre et al., Green et al., and MUTRON group are in accord with the calculated muon spectrum.     

Intrinsic <Emphasis Type="Italic">g</Emphasis><Subscript><Emphasis Type="Italic">K</Emphasis></Subscript> factors of odd-mass <Superscript>167–179</Superscript>Lu isotopes

In this paper, g _K -factors of the intrinsic magnetic moments and effective spin gyromagnetic factors (g _s^eff) of the ^167–179Lu isotopes have been studied within the Tamm-Dancoff approximation (TDA) (Kuliev et al, Sov. J. Nucl. Phys. 9, 185 (1969)) by using a realistic potential such as Woods-Saxon potential for the first time. The effects of the spin-spin and spin-isospin interactions on magnetic moments were investigated. The results of the theoretical calculations are compared with the experimental data for related nuclei. The experimental values of g _K and g _s^eff were computed from the observed magnetic moments (Georg et al, Eur. Phys. J. A3, 225 (1998)) using the spin matrix elements. The theoretical predictions for the g _K factors exhibit good agreement with the experimental g _K factors with increasing mass number A of the lutetium isotopes. The strongest influence of the neutron-proton spin interaction occurs at q = −1. Sufficient agreement between the calculated and the experimental values of g _K is obtained for κ = (45/A) MeV and q = −1.     

Structure functions of the deuteron and meson exchange currents

The deuteron structure functionsA(q ²)B(q ²) and polarization tensorT(q ²) are studied within the Bonn model with meson exchange currents taken into account. It is shown that it is necessary to take all these currents into consideration including the retardation effects. ForA(q ²) the contribution of retardation effects does not depend on the choice of vertex form factors; whereas forB(q ²) it essentially depends on the choice of strong vertices. The best agreement with experiment is achieved for the Bonn relativistic potential.Dedicated to the memory of M. Gmitro.     

The problems with M

M² is now widely used to characterize the quality of laser radiation. In the paraxial approach the inequality M²1 holds, if M² is defined by the second moments. Nevertheless, in some publications M²<1 is presented, either theoretically or experimentally (Wang et al., Optik 1995;100(1):8; Lu et al., Optik 1995;100(2):91; Wang et al., Optics and Laser Technology 1999;31:151). In particular, it is stated that for a superposition of axially shifted Gaussian spherical beams, M² can become smaller than one (Wang et al., Optics and Laser Technology 1999;31:151). These problems with M² are briefly summarized.     

Derivation of Absolute Depth-Intensity Spectrum under Standard Rock from the Recently Estimated Primary Cosmic Ray Spectrum

Using the recently derived primary cosmic ray nucleon spectrum from JACEE and GSFC balloon flight data and Fermilab results for pp → π^± + X anything inclusive reaction data in the light of Feynman scaling the depth-intensity spectrum under standard rock has been estimated. A precisely constructed range-energy relation has been applied in this analysis. The derived spectrum when corrected for range fluctuation agrees approximately with the experimental data under standard rocks measured by MIYAZAKI , BARTON , CASTAGNOLI et al., MEYER et al., BERGAMASCO et al., SHELDON et al. and BASCHIERA et al.     

Magnetic Fingerprints on the Spectra of One Electron and Two Electrons Interacting in Parabolic Quantum Dots

Magnetic fingerprints on the spectra of an electron interacting with a negatively charged ion in a parabolic quantum dot, and of two interacting electrons in such a dot, are investigated via a new pseudoperturbative methodical proposal. The effects of ion-electron and electron-electron interactions on the spectra are studied. The effect of the central spike (m ² – 1/4)/q ² on the spectral properties of the above problems is emphasized. Compared with those obtained by Zhu et al. [J. Phys.: Condens. Matter., Vol. 11 (1999) 229], via a series solution, the results are found in excellent accord. Higher excited states are also reported.     

Electromagnetic form factors for nucleons and pions at positive and negative q 2 in the model of quark-gluon strings

The electromagnetic form factors for pions and nucleons are considered within the model of quark-gluon strings, where the momentum-transfer dependence of hadronic form factors is determined by the intercepts of the corresponding Regge trajectories and by the Sudakov form factor. Analytic expressions found for form factors in the timelike region admit an analytic continuation to the spacelike region. The resulting form factors for pions and nucleons comply well with experimental data both for positive and for negative values of the squared momentum transfer q ². It is shown that the distinctions between the absolute values of the pion and nucleon form factors F _π(q ²), G _m (q ²), and F ₂(q ²) at positive values of q ² and those at negative values of this variable are associated with the analytic properties of the double-logarithmic term in the exponent of the Sudakov form factor. The spin structure of the amplitudes for quark transitions into hadrons that is proposed in the present study makes it possible to describe fairly well available experimental data on the Pauli form factor F ₂ and on the ratio G _e /G _m .     

q 2-convolution and itsq 2-Fourier transform

The functions on the lattice generated by the integer degrees ofq ² are considered, 0<q<1. Theq ²-shift operator is defined. The multiplicators and theq ²-convolutors are defined in the functional spaces which are dual with respect to theq ²-Fourier transform. Theq ²-analog of convolution of twoq ²-distributions is constructed. Theq ²-analog of an arbitrary order derivative is introduced. Presented at the 9th Colloquium “Quantum Groups and Integrable Systems”, Prague, 22–24 June 2000. The author was supported in part by the Russian Foundation for Fundamental Research (grant no. 0001-00143) and the NIOKR MPS RF     

Resistivity of two-dimensional systems in a magnetic field at the filling factor ν = 1/2

Experimental data on the diagonal resistivity ρ _xx of GaAs/AlGaAs heterostructures in a magnetic field at the filling factor ν = 1/2 have been compared with the existing theoretical predictions [B. I. Halperin et al., Phys. Rev. B 47, 7312 (1993) and F. Evers et al., Phys. Rev. B 60, 8951 (1999)]. The experimental results have been found to follow the relation ρ _xx (1/2) ∝ n ^?2 d ^?1.64, which disagrees with the predictions.     

Analysis of high temperature ammonia spectra from 780 to 2100 cm

A recently-recorded set [Hargreaves et al., Astrophys. J., in press] of Fourier transform emission spectra of hot ammonia is analyzed using a variational line list. Approximately 3350 lines are newly assigned to mainly hot bands from vibrational states as high as v₂ = 2. 431 new energy levels of these states are experimentally determined, considerably extending the range of known rotationally-excited states. Comparisons with a recent study of high J levels in the ground and first vibrational states [Yu et al., J. Chem. Phys., 133 (2010) 174317] suggests that while the line assignments presented in that work are correct, their energy level predictions suffer from problems associated with the use of very high-order perturbation series in the effective Hamiltonian. It is suggested that variational calculations provide a more stable method for analyzing spectra involving highly-excited states of ammonia.     

Theoretical study on behaviors of 1s22s-1s2np transition for Co24+ ion in the whole energy region

Non-relativistic energies of 1s²2s and 1s² np (n⩽9) states for Co²⁴⁺ ion are calculated by using the full-core plus correlation method. Our results of 1s²2s and 1s²2p states agree well with the high-precision results of Yan et al. Based on calculating the first-order corrections to the energy from relativistic and mass-polarization effects, we estimate the higher-order relativistic contribution and QED correction to the energy under a hydrogenic approximation. The transition energies, wavelengths and oscillator strengths for the 1s²2s−1s² np (n⩽9) transitions of this ion are calculated. The results agree with the experimental data available in literature satisfactorily. By combining with quantum defect theory, our theoretical predictions on the energy and oscillator strength of this ion are extrapolated to the whole energy region including continuous states.     

New predictions of a classic model

The predictions of the rigid rotor model concerning electromagnetic transverse form factors of rotational nuclei are explored. Results for inelastic scattering at 180° to the first 2⁺ state in ¹⁶⁶Er are presented and compared to those obtained in the projected Hartree-Fock (PHF) approach. Large discrepancies between both predictions have been found in the low-q region. The rigid rotor model predicts a cross section 50 to 100 times lower than that predicted by the PHF approach in the region0.25 fm^?1 ? q ? 0.4 fm^?1, where the first maximum appears.     

Spectrum and decay properties of diquonia

Using the interquark potential due to Bhaduri et al., the properties ofq ² q ^?2 systems are studied within a non-relativistic quark model. A systematics over the various flavorsu, d, s, c, b, over the total spinS and over the orbital angular momentumL=0, 1, 2, 3 is carried out, while the parity is taken as the natural one. Not only the spectrum, but also the decay properties of each state are evaluated and the wave functions are analyzed in term of dumbbell structure. We propose a number of new resonances which could have a very narrow width.     

Nucleon form factors of the isovector axial-vector current

The theoretical and experimental status of the isovector axial-vector current form factors G _A(q ²) and G _P(q ²) of the nucleon is reviewed. We also describe a new calculation of these form factors in manifestly Lorentz-invariant chiral perturbation theory (ChPT) with the inclusion of axial-vector mesons as explicit degrees of freedom.     

A measurement of the spin correlation parameter CNN (θ) in n-p scattering at 181 MeV

The spin correlation parameter C_NN has been measured for n-p elastic scattering at 181 MeV. A comparison with predictions from various phase shift sets and potential models reveals sizeable deviations from the for the data Paris potential and Saclay phase shifts. For the Paris potential the deviations are directly related to an overprediction of the ³D₂ phase shift parameter.     

Semileptonic B<Subscript>s</Subscript>→D<Subscript>sJ</Subscript>(2460)lν decay in QCD

Using three point QCD sum rule methods, the form factors relevant to semileptonic B_s→D_sJ(2460)ℓν decay are calculated. The q² dependences of these form factors are evaluated and compared with the heavy quark effective theory predictions. The dependence of the asymmetry parameter α, characterizing the polarization of the D_sJ meson, on q² is studied. The branching ratio of this decay is also estimated, and it is shown that it can easily be detected at LHC.