In this thesis, a detailed study is made of the phenomenon of Octet Enhancement in hadronic interactions. After a survey of the experimental consequences of Octet Enhancement is made in Chapter II, a review and discussion of the various theories of Octet Enhancement is given in Chapter III. In Chapter IV, a general group theorectical discussion, based on an extension of Glashow's Method (S. L. Glashovr, 1963) of spontaneous symmetry breaking is presented. A general theorem in connection with spontaneous symmetry breaking is stated and proved. The theorem lends itself to a number of interesting applications. Among these is a demonstration that if a unitary triplet exists in nature which is non-trivially coupled to the rest of the hadrons, then Octet Enhancement follows without recourse to any detailed dynamical assumption. In particular, the triplet need not be quarks in the sense of fundamental building blocks of all matter. It is also demonstrated group theoretically that ϕ-ω mixing can in principle occur as a particular form of spontaneous symmetry breaking, in exactly the same way that a spontaneous mass splitting can occur. Assuming Octet Dominance in the symmetry breaking of a degenerate nonet of vector mesons, it follows quite generally that the formulae [formulae omitted] must hold. Here again, no dynamical detail is required. In Chapter V, a bootstrap model consisting of an octet of vector mesons is constructed with which it is demonstrated step by step how Octet Enhancement follows from the intricate working of two dynamical principles — (a) the bootstrap hypothesis and (b) that the mesons participating in the bootstrap must be physical particles and not ghost states. In Chapter VI, the model is extended to study ϕ-ω mixing. A phenomenon which can be interpreted as a "sponteneous" ϕ-ω mixing is found to in fact occur. Furthermore, formulae (i) and (ii) also emerge from this model. The only extra assumption besides (a) and (b) that we have to make here is the mere "existence" of a unitary singlet vector meson whose "bare" mass (the mass of the particle before it is embroiled in the bootstrap) is equal to average mass of the octet. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

In this thesis we calculate the symmetric S-state contribution to the binding energy of the triton (H³) using the nucleon-nucleon potentials recently developed by Wong (1965). Towards this end we employ a modification of the equivalent two-body method used by Peshbach-Rubinow (1955). / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The differential cross sections for the production of definite lambda hypernuclear states, within the single scattering, impulse approximation, are calculated from the reaction n(K⁻,π⁻)Λ° on nuclear targets of helium, carbon and oxygen at various K-meson incident momentum. It is shown that these predictions are very sensitive to the three momentum transfer and to the wave function of the bound lambda in the hypernucleus. From the calculations, it is shown that it is possible to observe their production by studying the missing mass spectrum of the emitted pion. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The free neutron-proton elastic differential cross section has been measured at neutron beam energies of 212 and 418 MeV. . The experiment determined the angular distribution over the range 15°-180° (CM) in two segments, having the same overall normalization. The 15°-90° range was measured by detecting scattered neutrons in a scintillator and HWPC array. Normalization was obtained by moving the array into the direct neutron beam. Energy selection was made via a time of flight (TOF) measurement relative to the TRIUMF cyclotron RF. The neutron detector was calibrated absolutely using an associated particle technique, in which the recoil proton was detected. The ratio of coincidentally observed neutron-proton pairs to protons alone yielded the efficiency, which was used to calibrate neutron beam monitors. The remainder of the angular distribution was obtained by detecting the scattered protons in a magnetic spectrometer. Proton selection was made using the TOP through the spectrometer and the momentum. Energy selection was made via the BF TOF. Normalization was provided by the same monitors as used in the measurement of the forward half of the angular distribution. The normalization of d?/dΩ has been determined to about 3%, with statistical accuracies of about 1-3% on the individual data points. These data have been included in a phase shift analysis together with all world data, showing an improvement in the energy dependence of the differential cross section near 0° CM and in the phase shifts, notably, E₃. Together with the previously measured Wolfenstein parameters, unambiguous phase shifts in the I=0 system are obtained for the first time in the TRIUMF energy range. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

A separable potential model is constructed to describe the coupled ΣN-AN systems. From this the Σ single particle potential is developed including Pauli effects. The momentum space Schroedinger equation is then solved self-consistently for the complex eigenvalues of 1s and lp state Σ° hypernuclei. Arising from two quite distinct mechanisms these states are all found to be long lived. In s-states, Pauli suppression of the ΣN->AN conversion reduces the widths by as much as 50% from classical estimates in heavy nuclei, and in light nuclei produces widths as small as 1.8 MeV inΣ[sub=o;sup=5]He. In p-states, Pauli effects are relatively unimportant and the strong absorption of the potential creates extremely narrow quasi-bound states in the Σ continuum. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

This thesis presents new interaction potentials for studying systems of nucleons and pions at intermediate energies. Using a quantum field theory approach, the fundamental dynamical variables are taken to be the Fermion and Boson creation operators, F⁺ and B⁺. First, considering systems with only nucleons, a 2-body nucleon interaction potential is introduced, from which the familiar pair of coupled differential equations for the deuteron is derived. Next, turning to systems of nucleons and pions, focusing primarily on the reaction p+p → π⁺+d , we introduce unconventional, penta-linear interaction potentials of the form "F⁺F⁺FFB⁺ + adjoint". With these unconventional potentials, we can identify F⁺10> and B⁺10> with physical nucleons and physical pions— quite unlike the conventional situation with the Chew Hamiltonian, where F⁺10> cannot be identified with a physical nucleon. The differential scattering cross section for pp → π⁺d ( (with polarized incident protons) is then derived in terms of our potentials. Finally, we include a simple perturbation study of the deuteron state using our potentials. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Precise knowledge of parton distribution functions (PDFs) is necessary to the accurate calculation of QCD observables initiated by hadrons. The deep inelastic scattering (DIS) and lepton pair production (LPP) processes are primary sources of information on PDFs. Recent global fits for PDFs have used DIS data from the large Bjorken $x$, moderate $Q^{2}$ region. It is known that there are large logarithms in this kinematic region that can be resummed using threshold resummation techniques. The purpose of this study is to investigate the effects of simultaneously including DIS and LPP threshold resummation in the determinations of PDFs. The analysis includes a study of the effects of the choice of resummation prescription and of current resummation methods used in the LPP rapidity and $x_{F}$ distributions. It is demonstrated theoretically and phenomenologically that the current resummation methods for such distributions are approximations that lose accuracy at high rapidities or $x_{F}$. The unapproximated resummation formalism is extended to the $\overline{\mathrm{MS}}$ scheme in the minimal and Borel prescriptions and used in conjunction with resummation in DIS to perform a global fit. The resultant PDF sets that correspond to two choices of resummation prescription are analyzed to determine the effect of threshold resummation on PDF fits and its theoretical uncertainties. / A Dissertation submitted to the Department of Physics in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Spring Semester, 2015. / April 1, 2015. / PDF, Prescription, Resummation, Threshold / Includes bibliographical references. / Joseph F. Owens, III, Professor Directing Thesis; Ettore Aldrovandi, University Representative; Laura Reina, Committee Member; Susan Blessing, Committee Member; Winston Roberts, Committee Member.

Bibliography p. 214-226. / Exclusive measurements have been made of the reactions ⁴He(p,2p ), (p,pd), (p,pt) and (p,ph) at 100 MeV. The primary protons were measured at two angles, 45° and 60°, in coincidence with secondary protons, deuterons, tritons or helions covering a wide range of angles on the opposite side of the beam, from -15° to -90° in plane, and from 0° to 30° out-of-plane. The purpose of the experiment was to explore the validity of the Distorted Wave Impulse Approximation (DWIA) as a description of these quasifree knockout reactions, at all geometries where the knockout cross section is significant. Six particle telescopes, each consisting of two silicon detectors and a NaI detector, were used to measure the coincident particles. The experimental data are presented in the form of energy-sharing distributions, which were generated by projecting the two-dimensional quasifree knockout loci onto the energy axis of the primary proton. The comparison between these energy-sharing distributions and the curves calculated by means of the DWIA is satisfactory for all geometries, except at the most forward secondary angles for the (p,pt) and (p,ph) reactions. It is concluded that the DWIA is an adequate formalism for modelling the quasifree knockout reactions induced by 100 MeV protons on ⁴He. Based on this conclusion, the total contribution of quasifree knockout to the existing inclusive (p,p') spectra has been calculated by integrating the DWIA cross sections over the solid angles of the secondary particles. The spectroscopic factors used were those extracted from the coincidence data. For the (p,pn) reaction, it was assumed that the spectroscopic factors were the same as for (p,2p). It is found that 70 ± 10% of the inclusive continuum yields is attributable to quasifree scattering, with ~30% arising from multiple scattering. At low energies of the scattered proton, the knockout of nucleons constitutes over 90% of the quasifree component, whereas at high energies the knockout of deuterons, tritons and helions dominates the yield. Thus the absence of discernable quasifree peaks in the inclusive spectra is probably due to the cluster knockout contributions filling in the yield at higher energies.

The production of direct photons in association with jets can be used to probe gluon parton distribution functions as well as to test perturbative Quantum Chromodynamics. This thesis presents the measurement of the triple differential cross section for photon plus jet evehts as a function of photon transverse momentum (pɣT), photon pseudorapidity (ηɣ), and jet pseudorapidity (ηjet). The measurement is made using 19.7 fb⁻¹ of data collected by the Compact Muon Solenoid detector in proton-proton collisions at the center-of-mass energy of 8 TeV. The kinematic regions probed are 40 [less than] pɣT [less than] 1000 GeV, |ηɣ| [less than] 2.5 and |ηjet| [less than] 2.5. These results are compared to next-to-leading order theoretical predictions. / A Dissertation submitted to the Department of Physics in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Summer Semester 2016. / June 3, 2016. / Includes bibliographical references. / Andrew Askew, Professor Co-Directing Dissertation; Susan Blessing, Professor Co-Directing Dissertation; Qing-Xiang Sang, University Representative; Todd Adams, Committee Member; Joseph Owens, Committee Member; Jorge Piekarewicz, Committee Member.

The present theoretical framework to describe the universe in particle level, the Standard Model describes only 4% of the matter-energy budget of the universe. There are many theories which attempt to describe the universe beyond the scope of the Standard Model. This dissertation describes a search for supersymmetry, a beyond Standard Model theory, using data collected by the Compact Muon Solenoid detector with integrated luminosity of 2.3 fb⁻¹ at a center of mass energy of 13 TeV during 2015. The data were produced in proton-proton collisions at the Large Hadron Collider near Geneva, Switzerland. This search was performed with events having two photons and missing transverse energy in the final state. This final state was motivated by general gauge mediated supersymmetry breaking, one of the theories on how breaking of supersymmetry can be mediated. No significant excess over the expected background was observed. The result was interpreted with simplified model scans and 95% upper limit on production cross sections are provided. / A Dissertation submitted to the Department of Physics in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Summer Semester 2016. / June 29, 2016. / 13 TeV, CMS, Missing Transverse Energy, Photon, Supersymmetry / Includes bibliographical references. / Andrew Askew, Professor Directing Dissertation; Gary Tyson, University Representative; Todd Adams, Committee Member; Laura Reina, Committee Member; Jorge Piekarewicz, Committee Member.