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A Caltech Library Repository Feedhttp://www.rssboard.org/rss-specificationpython-feedgenenWed, 31 Jan 2024 19:04:48 +0000A Dual Quark Model with Spin
https://resolver.caltech.edu/CaltechTHESIS:04202018-125942170
Authors: {'items': [{'id': 'Ellis-Stephen-Dean', 'name': {'family': 'Ellis', 'given': 'Stephen Dean'}}]}
Year: 1971
DOI: 10.7907/G3AD-N729
<p>A dual quark model is developed from the usual Veneziano model
by explicitly including the Dirac spin of the quarks. Resonances
appear without the parity doubling and new ghosts present in previous
models with spin. This is accomplished by eliminating the contributions
of the negative parity components (MacDowell-twins) of the
spin quarks 1/2 through the introduction of fixed J-plane cuts. The
resonances belong to an SU<sub>6</sub> symmetric spectrum identical, on the
leading trajectory, with that of the usual static symmetrical quark
model. All resonances couple via SU<sub>6w</sub> x O<sub>2Lz</sub> symmetric vertices
and the model factorizes with essentially the same degeneracy as the
usual Veneziano model. As a consequence of requiring these two
features the model acquires further new structure which is studied
in detail in terms of the asymptotic behavior of the model. This
new structure leads to unavoidable "background" contributions to
the imaginary parts of the amplitudes not present in previous dual
models. This situation is examined and interpreted in the language
of Finite Energy Sum Rules.</p>
<p>In order to test the basic features of the model explicit
calculations are made for the case of pion-nucleon scattering in
the Regge limit. To make the numerical work easier a somewhat
simplified version of the model is used. Although the results of
the calculations are suggestive of reasonable J-plane structure for
the various amplitudes, i.e., the location of Regge pole-fixed cut
interference is reasonable from the standpoint of the data, the
overall kinematic behavior of the amplitudes is definitely not
compatible with what is measured. However, it is noted that this
kinematic behavior depends strongly on those details of the model
which were simplified in the present study. If such models are to
be unambiguously and successfully tested against data, future studies
must treat these details more completely and realistically, including
both unitarity and symmetry breaking effects.</p>https://thesis.library.caltech.edu/id/eprint/10823