13,649 research outputs found
Calculation of the pentaquark width by QCD sum rule
The pentaquark width is calculated in QCD sum rules. Result for
show, that can vary in the region less than
1. The main conclusion is, that if pentaquark is genuine states then sum
rules really predict the narrow width of pentaquark , and the
suppression of the width is both parametrical and numerical.Comment: 8 Ppages, 3 figures,the numerical error was corrected, two figures
are modified. In the limit of errors the result did not change significantl
Perturbation of a lattice spectral band by a nearby resonance
A soluble model of weakly coupled "molecular" and "nuclear" Hamiltonians is
studied in order to exhibit explicitly the mechanism leading to the enhancement
of fusion probability in case of a narrow near-threshold nuclear resonance. We,
further, consider molecular cells of this type being arranged in lattice
structures. It is shown that if the real part of the narrow nuclear resonance
lies within the molecular band generated by the intercellular interaction, an
enhancement, proportional to the inverse width of the nuclear resonance, is to
be expected.Comment: RevTeX, 2 figures within the file. In May 2000 the title changed and
some minor corrections have been don
Pion Light-Cone Wave Functions and Light-Front Quark Model
We discuss a relation between the light-front quark model and QCD. We argue
that this model can be used for an evaluation of the light-cone wave functions
for moderate values of "u", but that it is inapplicable for this purpose in the
region near the ends points u=0,1. We find additional support for a recent
analysis in which it was claimed that the twist-two pion wave function attains
its asymptotic form. The asymptotic twist-four two-particle wave function is
also in good agreement with the light-front quark model.Comment: 11 pages and 2 PS-figures in one gz-compressed .tar file. Minor
chang
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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