Theoretical particle physics. Progress report, 1 December 1974--30 November 1975

The research can be divided into two categories, the first dealing with the phenomenological treatment of two-body collisions, and the second dealing with symmetry-breaking and more speculative topics such as charm. In the first category, spin-correlations in proton-proton elastic scattering, made a model of inclusive interactions using triple-pomeron exchange, calculated the cross section and polarization in the reaction pp → π+d using Regge exchange, estimated masses and widths of resonances by extrapolating scattering amplitudes to their poles in the complex energy plane, and are now undertaking a phase-shift analysis of pion-nucleon scattering at intermediate energies. In the second category, mass relations were obtained for charmed hadrons using broken SU(4) and SU(8) within the framework of the quark and quark-diquark models, have undertaken a program of calculating meson masses in the quark model using attractive 1/r plus linear confining potentials, and have calculated π+-π0 mass difference in the quark model. (U.S.)