14,356 research outputs found

### Delta-Isobar Magnetic Form Factor in QCD

We consider the QCD sum rules approach for Delta-isobar magnetic form factor
in the infra-red region $0<Q^2<1GeV^2$. 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

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 $N$ caped (and probably floored) returns. It is
noticed, that $1/\sqrt{N}$ 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

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 $\omega^2
>\omega^2_0$) and soft (with frequencies $\omega^2 <\omega^2_0$) ones,
$\omega_0$ 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 $V(x)=\lambda
x^4$ 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

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

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 $\Xi_{Q}$ Baryons in Light Cone QCD Sum Rules

The magnetic moments of heavy $\Xi_{Q}$ 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 $\rho NN$, $\rho\Sigma\Sigma$ and $\rho\Xi\Xi$ with light-cone QCD sum rules

In this article, we calculate the strong coupling constants of the $\rho NN$,
$\rho\Sigma\Sigma$ and $\rho\Xi\Xi$ 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 $F/(F+D)$
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

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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