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Nuclear electroexcitations above the giant resonance energy· region in electron scattering are studied using the quasielastic model. A realistic Woods-Saxon single· particle potential is used in the calculation. The excitation. functions Jor large as welL as small momentum transfers to nuclei are well explained within our model. The position and the width of the quasielastic peak are shown to reflect the binding energies of deep hole states. Our result supports values of the binding energies obtained by the recent (e, e' p) experiment. A scal­ ing hypothesis is considered to connect experimentaJ data on different momentum and energy transfers and use of ,such a hypothesis is discussed in. making an estimate of the non-resonant background term in the giant resonance region.

Possible existence of the universal V=t=A coupling and the global symmetry in the non­ leptonic hyperon decays is discussed. The observed deviations from the expected symmetries in actual decays are explained as effects due to the mesonic structure of hyperons. In a close relation with the idea of the global symmetry a new isotopic spin is defined, which is 1/2' for all the baryons and integer for K. The conservation law of this isotopic spin is satisfied in the non-leptonic decays.

We study those restrictions upon the branching ratios of different decay modes of ${\ensuremath{\Sigma}}^{+}$, ${\ensuremath{\Lambda}}^{0}$, and ${\ensuremath{\theta}}^{0}$ imposed by the invariant property of a system composed of nucleons, pions, hyperons, and heavy mesons under the Wigner time reversal. These restrictions give, in fact, upper and lower limits on the various branching ratios. Later, we use a more or less specific model of hyperons and $\ensuremath{\theta}$ mesons in order to get other possible restrictions on the branching ratios. These results are model-dependent, and subsequently provide a possible test of the model we have chosen.

A simple model for the nucleon-antinucleon interactions is presented, in which the nucleon or the antinucleon is regarded as composed of two parts, the pion cloud and the " core". The latter is characterized by two properties : i) it acts as a n.early black body for an incoming antiparticle wave, and ii) its characteristic time for ato.nihilation is much shorter than the oscillation period of the outer pion cloud. These simple assumptions lead to natural semi-quantitative explanations of the salient features of the experimental information so far available concerning the nucleon-antinucleon reaction and capture processes. Some arguments are added to look for a justification of such an approach.

The possibility is considered that there exists a universal V-A interaction and complete symmetry in the nonleptonic decay of hyperons. The departure from the expected symmetry that is observed in actual decays Is explained by effects caused by the mesonic structure of hyperons. In close connection with the idea of complete symmetry, a new isotopic spin is defined, which is equal to 1/2 for all baryons and to 0 or 1 for K mesons. The law of conservation of this isotopic spin holds in nonleptonic decays.

The existence of a sharp pion-pion resonance is assumed for the T=j=l state at about 600 Mev. This resonance state is approximately replaced by a real T= j =1 particle p±' 0 and its interactions with the pion field and the electro-magnetic field are determined. The calculation of pion-nucleon. scatterings through pN intermediate states shows in the Born approximation that very strong attractive forces seem to exist for both T=1/2, dS/2 and T=1/2, f5/2 pionnucleon states at about the p-production threshold energy. The former is identified as the second and the latter as the third resonance 6bserved in the pion-nucleon scatterings. A similar calculation predicts the possible appearance of the second resonance and the suppression of the third one in the photo-pion productions. A tentative model for explaining the fourth maximum observed in the pion-nucleon scattering is proposed along the similar line.

The possibility that some of the intermediate vector bosons of the weak interaction might be produced, several orders of magnitude more strongly than previously estimated, is studied. Intermediate vector bosons interact with the strangeness-non-changing baryon current, the strangeness-changing baryon current, and the lepton current. Circumstance that could give rise to copious production of the intermediate bosons are presented. (C.E.S.)