14,954 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 . 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 caped (and probably floored) returns. It is
noticed, that 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 ) and soft (with frequencies ) ones,
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 is demonstrated. Ground state energy of the unharmonic oscillator is
calculated.Comment: 16 pages, 1 Figure, CEBAF-93-03.(Standard 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
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
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