Two topics in elementary particle physics: The reaction [photon-neutron going to pion-nucleon] at high energies. K leptonic decay and partially conserved currents

Citation

Zweig, George (1964) Two topics in elementary particle physics: The reaction [photon-neutron going to pion-nucleon] at high energies. K leptonic decay and partially conserved currents. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechETD:etd-12112002-091415

Abstract

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1. [Photon-neutron going to pion-nucleon].

The process [photon-neutron going to pion-nucleon] is studied at high energies in both the forward and backward directions. The helicity formalism is used. Contributions from the [rho], [omega], [phi] and [pi] trajectories in the t channel and from the [...],[...], and [...] trajectories in [...] channel are included. Polarization formulae for the final state nucleon are given. If we may neglect cuts in the angular momentum plane, then at high energies for momentum transfers -t >> [mu][superscript 2][subscript pi] the [rho] trajectory should dominate charged pion photoproduction in the forward direction. A curde estimate of the cross section yields [...]. However, the pion trajectory is expected to be important for small momentum transfers up to very high energies. For forward neutral pion photoproduction both the [rho] and [omega] trajectories should be important. The cross section is estimated to be [...] ~ [...]. For photoproduction in the backward direction, the situation is much more complex with at least three trajectories contributing to [...]. However, since the same set of trajectories are to be used in [...] scattering, backward [...] scattering and backward photoproduction are expected to have the same energy dependence. Assuming that the [...] trajectory dominates with [...], we obtain [...].

2. K Leptonic Decay and Partially Conserved Currents.

An operational definition for the partial conservation of the strangeness changing vector current is given and applied to leptonic K[superscript +] and K[degrees][subscript 2] decay. The K[superscript *] resonance is explicitly included in the calculation and quantitative agreement with experiment is obtained. A detailed comparison with the K[superscript +] data of Brown et.al. and Dobbs et al. is given. Because of rapid variations of a form factor, it is found that the data of these two groups are not in contradiction. From the K[degrees][subscript 2] experiment of Luers et. al., I = 1/2 and 3/2 currents are seen to exist. [...]decay is briefly considered. It is found that an explanation for the slowness of K leptonic decay and the vector part of [...]decay may be connected with the partial conservation of the strangeness changing vector current.

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