[en] The mechanical models of the bi-local fields and the string models are discussed in the formal point of view. Since the formulation of the extended particle pictures has no unique way, there are various formulations even in the simplest bilocal models. We confine ourselves mainly in the formulations by following which the interactions have been investigated. The scattering amplitudes and the form factors are discussed qualitatively. Some comments on the subsidiary conditions suppressing the relative time freedom are given by following Dirac's formalism. A short discussion of the bi-local model with spin is also shown by introducing Grassmann variables as classical variables corresponding to spin freedom. As to the string model, we have discussed various interesting but unsolved problems; namely, the electromagnetic interactions, the string with massive ends, the spinning string and so on. We have proposed tentative prescriptions for treating some of these problems. We also discuss the different point of view concerning the string model. That is, we show that the difference equation furnishes us the same result as that given by the string model. (author)

[en] We expound systematically a relativistic quantum-mechanical model consisting of two constituent particles bound by action-at-a-distance. The theory has clear 'realistic' foundation since it is obtained as the quantization of classical mechanics for the relativistic two-body system, in which action-at-a-distance works instantaneously when viewed in the CM rest frame. It is shown that consistent quantization favors a distinct model to be called SROM (simple relativistic oscillator model), which is represented by a simple bilocal wave equation and an associated subsidiary condition, and implies automatic confinement of constituents. Further properties of this model are worked out and are shown to be suitable for a unified description of mesonic states. The theory is the one which has been investigated for some years but it is presented here in a sufficiently synthetic context and is elaborated in various respected. Historical development of various related bilocal models, together with some critical analyses in them, are also given. (author)

[en] A systematic investigation on the world of hadrons is made based on a unified model without the color freedom. Here respective hadrons are described by the Fierz-components of multi-local fields, which play a role of wave functions in the usual approach and, at the same time, are second-quantized by following the usual spin-statistics connection. First in Part I we introduce a new Fock-space concerning a ''urciton'' which might reflect an exciton of some ''extended object'' and is quantized with a Bose-type commutator. Various multi-local fields for both non-exotic and exotic hadrons are organized as Fock-amplitudes of a general vector in this space. Our kinematical framework as a relativistic quark model has a characteristic feature to be called a boosted SU(6) x O(3) scheme, and is applied successfully to phenomenological analyses of various phenomena concerning non-exotic hadrons in Part II. Which is true, our ''white'' Bose quarks or the conventional colored Fermi quarks[ This problem is discussed in Part III, investigating mainly non-leptonic weak interactions and level structures of exotic particles which become very much different in the two approaches, reflecting the difference of supposed quark-statistics. (author)

No abstract available

[en] Leading proton spectrum in high energy proton-nucleus collisions is analyzed on the basis of the intranuclear cascade model. The model includes the possibility of low attenuation of leading proton in the nuclear matter at high energies. Experimental data at 24 GeV/c with Be, Al, Cu and Pb targets are consistent with the conventional cascade model. It is difficult, however, to understand p-Be data at 200 GeV/c in terms of this conventional model. On the assumption that the particles entering into the nucleus interact with the nucleons only within one mean free path on the average and that they become inactive through the nucleus, the theoretical results come to be more consistent with the data than the case of the conventional model. (author)

[en] The vacuum structure of quantum chromodynamics (QCD) is studied, with emphasis on massless QCD. An interacting gas of instantons is replaced by an ideal gas of effective instantons, which incorporate effects of new tunnelings. The existence of a critical value theta sub(c) in the theta-vacua is shown. Chirally asymmetric vacua of massless QCD require two-parameter dependence, which allows dynamical quark mass generation. Chiral U(N) x U(N) symmetry is realized in the Goldstone mode at ⁺theta⁺ = theta sub(c). The U(1) Goldstone boson becomes massive for theta, ⁺theta⁺ < theta sub(c). (author)

No abstract available

[en] Recent e-d elastic scattering experiments show that the deuteron elastic electromagnetic form factor behaves like (Q²)^-5 at large momentum transfers. This fact suggests that we can observe a possible six-quark configuration besides the ordinary proton-neutron bound state configuration in the deuteron state, because the power 5 is considered to come directly from the degree of freedom of the internal orbital motion in the relativistic harmonic oscilator model, for the same reason as the pion form factor of the simple pole type and the nucleon form factor of the dipole type. Using the theoretical formula of the deuteron form factor given by the model, we analyze the experimental data and then determine the probability of finding the six-quark configuration. Finally, a simple potential model is introduced to connect the probability with possible dibaryon resonance states. Consistent numerical relations are obtained between the deuteron form factor and the dibaryon resonances. (author)

[en] We point out that the dibaryons recently discovered and predicted as πNN resonances play an important role in π-α scattering in the 33-resonance energy region. It should be also the case for π-nucleus scattering in general. (author)

No abstract available