14,356 research outputs found

    Delta-Isobar Magnetic Form Factor in QCD

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    We consider the QCD sum rules approach for Delta-isobar magnetic form factor in the infra-red region 0<Q2<1GeV20<Q^2<1GeV^2. The QCD sum rules in external variable field are used. The obtained formfactor is in agreement with quark model predictions for the Delta-isobar magnetic moment.Comment: 13 pages, CEBAF-TH-93-02, Latex, 1 Figur

    Cumulant Expansion and Monthly Sum Derivative

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    Cumulant expansion is used to derive accurate closed-form approximation for Monthly Sum Options in case of constant volatility model. Payoff of Monthly Sum Option is based on sum of NN caped (and probably floored) returns. It is noticed, that 1/N1/\sqrt{N} can be used as a small parameter in Edgeworth expansion. First two leading terms of this expansion are calculated here. It is shown that the suggest closed-form approximation is in a good agreement with numerical results for typical mode parameters.Comment: 8 pages, 2 figure

    Soft Modes Contribution into Path Integral

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    A method for nonperturbative path integral calculation is proposed. Quantum mechanics as a simplest example of a quantum field theory is considered. All modes are decomposed into hard (with frequencies ω2>ω02\omega^2 >\omega^2_0) and soft (with frequencies ω2<ω02\omega^2 <\omega^2_0) ones, ω0\omega_0 is a some parameter. Hard modes contribution is considered by weak coupling expansion. A low energy effective Lagrangian for soft modes is used. In the case of soft modes we apply a strong coupling expansion. To realize this expansion a special basis in functional space of trajectories is considered. A good convergency of proposed procedure in the case of potential V(x)=λx4V(x)=\lambda x^4 is demonstrated. Ground state energy of the unharmonic oscillator is calculated.Comment: 16 pages, 1 Figure, CEBAF-93-03.(Standard LATEX file

    Massless Fermions on the Lattice

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    We consider a nonlocal lattice action for fermions fermion doubling in lattice theories. It is shown, that it is possible to avoid the fermionic doubling in the case of free fermions, but this approach does not reproduce results for the effective action for gauge fields in the continuum theory, because the high frequency fermion modes have a strong dependence on the gauge field.Comment: 16 pages, LATEX, 1 Figure (uuencoded PS-file is attached to the end of the LATEX file

    Lattice and Continuum Theories

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    We investigate path integral formalism for continuum theory. It is shown that the path integral for the soft modes can be represented in the form of a lattice theory. Kinetic term of this lattice theory has a standard form and potential term has additional nonlocal terms which contributions should tend to zero in the limit of continuum theory. Contributions of these terms can be estimated. It is noted that this representation of path integral may be useful to improve lattice calculations taking into account hard modes contribution by standard perturbative expansion. We discuss translation invariance of correlators and the possibility to construct a lattice theory which keeps rotary invariance also.Comment: (Latex, 6 pages), preprint CEBAF-TH-94-1

    Magnetic Moments of Heavy ΞQ\Xi_{Q} Baryons in Light Cone QCD Sum Rules

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    The magnetic moments of heavy ΞQ\Xi_{Q} baryons containing a single charm or bottom quark are calculated in the framework of light cone QCD sum rules method. A comparison of our results with the predictions of the quark models is presented.Comment: 26 Pages, 8 Figures and 1 Tabl

    Analysis of the vertices ρNN\rho NN, ρΣΣ\rho\Sigma\Sigma and ρΞΞ\rho\Xi\Xi with light-cone QCD sum rules

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    In this article, we calculate the strong coupling constants of the ρNN\rho NN, ρΣΣ\rho\Sigma\Sigma and ρΞΞ\rho\Xi\Xi in the framework of the light-cone QCD sum rules approach. The strong coupling constants of the meson-baryon-baryon are the fundamental parameters in the one-boson exchange model which describes the baryon-baryon interactions successfully. The numerical values are in agreement with the existing calculations in part. The electric and magnetic F/(F+D)F/(F+D) ratios deviate from the prediction of the vector meson dominance theory, the SU(3) symmetry breaking effects are very large.Comment: 19 pages, 6 figures, revised version, add more discussions(Correct writing errors

    Vector, Axial, Tensor and Pseudoscalar Vacuum Susceptibilities

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    Using a recently developed three-point formalism within the method of QCD Sum Rules we determine the vacuum susceptibilities needed in the two-point formalism for the coupling of axial, vector, tensor and pseudoscalar currents to hadrons. All susceptibilities are determined by the space-time scale of condensates, which is estimated from data for deep inelastic scattering on nucleons
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