CaltechTHESIS: Article
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A Caltech Library Repository Feedhttp://www.rssboard.org/rss-specificationpython-feedgenenWed, 18 Sep 2024 13:31:47 -0700Two Topics in Elementary Particle Physics: I. Crossing as a Group and Elimination of Exotic Channels. II. Real Parts of Meson-Nucleon Forward Scattering Amplitude
https://resolver.caltech.edu/CaltechTHESIS:08242015-093245359
Year: 1970
DOI: 10.7907/51R2-EF81
<p>I. Crossing transformations constitute a group of permutations
under which the scattering amplitude is invariant. Using Mandelstem's
analyticity, we decompose the amplitude into irreducible representations
of this group. The usual quantum numbers, such as isospin or
SU(3), are "crossing-invariant". Thus no higher symmetry is generated
by crossing itself. However, elimination of certain quantum numbers
in intermediate states is not crossing-invariant, and higher symmetries
have to be introduced to make it possible. The current
literature on exchange degeneracy is a manifestation of this statement.
To exemplify application of our analysis, we show how, starting with
SU(3) invariance, one can use crossing and the absence of exotic
channels to derive the quark-model picture of the tensor nonet. No
detailed dynamical input is used.</p>
<p>II. A dispersion relation calculation of the real parts of forward
π<sup>±</sup>p and K<sup>±</sup>p scattering amplitudes is carried out under the assumption
of constant total cross sections in the Serpukhov energy range.
Comparison with existing experimental results as well as predictions
for future high energy experiments are presented and discussed.
Electromagnetic effects are found to be too small to account for the
expected difference between the π<sup>-</sup>p and π<sup>+</sup>p total cross sections at
higher energies.</p>https://resolver.caltech.edu/CaltechTHESIS:08242015-093245359