Citation
Colglazier, Elmer William, Jr. (1971) Two Topics in Elementary Particle Physics: (1) Quark Graphs and Angular Distributions in the Decays of the AxialVector Mesons. (2) Universal CurrentCurrent Theories and the NonLeptonic Hyperon Decays. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/HBFX4095. https://resolver.caltech.edu/CaltechTHESIS:04192018085253797
Abstract
The Thesis is divided into the following two parts:
(1) We examine three aspects of the axialvector mesons: (i) angular distributions of the I = 1 states, (ii) mixing of the I = 1/2 states, and (iii) absence of the I = 0 states.
Using a model of mesons decaying via production of a quarkantiquark pair with the quantum numbers of the vacuum, we relate the angular distributions in the decays A_{1}→ ρπ and B → ωπ, predicting 2(g_{1}/g_{0})A_{1} = (g_{0}/g_{1})_{B} + 1. This relation is consistent with the present, somewhat ambiguous experimental data. Also, we describe satisfactorily, in terms of two parameters, the partial widths of the 0^{+}, 1^{+}, and 2^{+} mesons decaying into 1^{}0^{} and 0^{}0^{} pairs. The prediction of the model is that SU(6)_{W} x 0(2)_{L}_{Z} relations hold among all the D waves and among all the S waves, but not between the two groups. In fact, our twoparameter fit to the data entails a ratio of S wave to D wave amplitudes of approximately the same magnitude but opposite sign to that implied by SU(6)_{W} x 0(2)_{L}_{Z}. Unlike the widths, the angular distributions are sensitive to the relative sign and are thus crucial in determining that the fit of our model differs considerably from the SU(6)_{W} solution.
Parameters of the fit are applied to the l^{+} kaons, which may mix with one another. The results are sensitive to the mixing angle ø, and merely assuming lower bounds on widths of both physical states establishes the limits 10° ≤ ø ≤ 35° As a result of this mixing, one predicts: (a) the suppression of the K*π mode of the lower peak, (b) the suppression of the ρK mode of the upper peak, and (c) decay distributions in the K^{*}π mode similar to that of the A_{1} for the lower state and to that of the B for the higher.
The properties of the missing isoscalar mesons are described with particular emphasis on the ninth 1^{++} state. Expected properties of this meson, the D', include: (a) assignment to a weakly mixed SU(3) singlet, predicted by duality and confirmed by the GellMannOkubo mass formula; (b) a mass of ~950 MeV, predicted by superconvergence with assumptions about the relative couplings of D and D’; (c) decay modes ηππ and π^{+}π^{}γ; and (d) the possibility of a suppressed ρ signal in the π^{+}π^{} spectrum of the π^{+}π^{}γ final state, despite the expectation that the pions are in a state with I = J = 1. These features suggest that a recently reported meson near this mass with decay modes ηππ and π^{+}π^{}γ may be a candidate for this state, although J^{pc} = 1^{+} is also a definite possibility for the new meson.
(2) Because of the limited evidence for the VA Cabibbo theory in the nonleptonic weak decays, we examine the compatibility with experiment of more general currentcurrent theories. These theories, constrained by universality, are constructed from the neutral and charged currents obtainable in the quark model, i.e., scalar, pseudoscalar, vector, axialvector, and tensore Using current algebra and PCAC, a certain class of these theories, including Cabibbo's, is found to be consistent with the S wave amplitudes for the nonleptonic hyperon decays. The P wave amplitudes remain unexplained. Nevertheless, another class of theories, also including VA, plus the assumption of a symmetric quark model, predict the ΔI = 1/2 rule.
Item Type:  Thesis (Dissertation (Ph.D.))  

Subject Keywords:  Physics  
Degree Grantor:  California Institute of Technology  
Division:  Physics, Mathematics and Astronomy  
Major Option:  Physics  
Thesis Availability:  Public (worldwide access)  
Research Advisor(s): 
 
Thesis Committee: 
 
Defense Date:  24 May 1971  
Funders: 
 
Record Number:  CaltechTHESIS:04192018085253797  
Persistent URL:  https://resolver.caltech.edu/CaltechTHESIS:04192018085253797  
DOI:  10.7907/HBFX4095  
Default Usage Policy:  No commercial reproduction, distribution, display or performance rights in this work are provided.  
ID Code:  10820  
Collection:  CaltechTHESIS  
Deposited By:  Tony Diaz  
Deposited On:  25 Apr 2018 23:50  
Last Modified:  21 Dec 2019 02:24 
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