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The notion of localizability of field theory is discussed. New criteria for localizability are found and the relationship between Lagrangian and localizability is sketched.

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A simple derivation of the quark model relations between the transversity amplitudes is given. The problem of the choice of the spin reference frame in which the additivity assumption holds is discussed. It is shown that all these quark model relations can be obtained from some simple geometrical postulates.

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A set of linear relations for the measurable generalized statistical tensors completely equivalent to the quark model predictions for the transition amplitudes for the reaction \(0^-+{\frac {1}{2}}^+ \to 1^-+{\frac {3}{2}}^+\) is given. The given relations can be tested directly by means of experimental data for joint decay distributions of the final particles.

abstract

Dans cet article nous démontrons, qu’il est possible d’obtenir les théorèmes de Greenberg et Low, de Froissart, etc. dans une théorie des champs quantifiés, où le principe de causalité peut être modifié. Cela signifie que la vérification expérimentale de ces théorèmes peut ne nous donner aucune information sur la validité des principes fondamentaux à hautes énergies.

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Daxis ce travail, nous démontrons qu’il est possible d’obtenir aussi lea relations asymptotiques dana une théorie des champs quantifies oú le principe de causalité peut être modifié. Cela signifie que la vérification expérimentale de la relation du type Pomeranchuk peut ne nous donner aucune information surla validité des principes fondamentaux de la théorie des champs quantifiés. On ne peut pas servir des relations asymptotiques comme critère bien fondé pour vérifier la validité de ces principes.

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The binding energy of a \({\mit \Lambda }\) particle in nuclear matter, \(B_{\mit \Lambda }(\infty )\), is calculated in the frame of the self-consistent Brueckner \(\cal {K}\) matrix theory. In the \(\cal {K}\) matrix equations pure kinetic energies in the intermediate states are used. The expression for \(B_{\mit \Lambda }(\infty )\), which includes the rearrangement energy, is derived in the case of a \({\mit \Lambda }\)N interaction which is spin dependent, has a tensor and spin–orbit part and contains a hard core. Calculations have been performed with the modified Herndon–Tang potentials and with a one-boson-exchange potential. The tensor suppression effect is estimated to be about 2 MeV, which includes important contributions of the \(^3P {\mit \Lambda }\)N interaction. The role of the self-consistency requirement in the tensor suppression effect is discussed.

abstract

To establish the \(X^0\)(960) meson spin-parity it is suggested to study the forward production of \(X^0\) in the reaction \(K^-p \to X^0 {\mit \Lambda }\) with the polarized proton.

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The kinematical behaviour of the three-body decay helicity amplitudes at the boundary of the physical region and of the decay transversity amplitudes at the thresholds and pseudothresholds is discussed. The three-body decay amplitudes possess the threshold and pseudothreshold singularities in \(s\), \(t\) and \(u\).

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The recently observed violation of exchange degeneracy rules for charge- and strangeness- exchange meson–baryon scattering is discussed in the framework of the quark model. It is shown that one can qualitatively describe the effect using the model in which \(q\)–\(q\) and \(q\)–\(\bar q\) amplitudes have Regge form with exact exchange degeneracy and all observed deviations are caused by three-quark (\(q\)–\(qq\)) scattering.

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An experimental test of the hypothesis that fixed \(j\)-plane singularities dominate the high-energy photoproduction is discussed.

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A method of evaluation of the absorption corrections by means of an expansion in a rapidly convergent power series is proposed. The resulting formulae are straightforward and easy for numerical calculations.

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A sample of 164 \(K^-\) interactions with emulsion nuclei with \(^5_{\mit \Lambda }\)He hypernuclei among secondaries were studied. The invariant mass distributions for \(^5_{\mit \Lambda }\)He–\(p\) and \(^5_{\mit \Lambda }\)He–\(\alpha \) systems in these stars were obtained and analysed. No maxima corresponding to particle-unstable \(^6_{\mit \Lambda }\)Li or \(^9_{\mit \Lambda }\)Be\(^*\) systems (decaying into \(^5_{\mit \Lambda }\)He and a proton or into \(^5_{\mit \Lambda }\)He and an \(\alpha \)-particle, respectively) were observed; this indicates a low, if not zero, value of cross-section for production of such systems.

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The cross-sections for the production of short-lived isomeric states in \(^{77}\)Se, \(^{122}\)Sb, \(^{137}\)Ba, \(^{167}\)Er and \(^{179}\)Hf‘67Er and \(^{179}\)Hf through the (n,2n) and (n,n’) reactions using 14.5 MeV neutrons have been given. The (n,n’\(\gamma \)) cross-sections are reported for the first time. Estimates have been obtained for isomeric ratios and spin cut-off parameter using Huizenga and Vandenbosch method and Gilbert and Cameron level density model.

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A simple method of deriving the quark model predictions for processes \(0^-{\frac {1}{2}}^+\to J^P 3{\frac {3}{2}}^+\) is presented. The cases \(J^P =0^{\pm }\), 1\(^{\pm }\), and 2\(^+\) are discussed explicitly. The method is extended to cover the description of interfering resonances. As an example the \(2^+\)–\(0^+\) interference is described.

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We investigate the spinor representations of the complex Poincaré group in the case when the complex mass of “the particle” is different from zero. The spinor representations of the complex Poincaré group are non-equivalent to the unitary representations, but they are equivalent to the unitary representations, when we restrict to the real Poincaré group.

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We construct the spinor representation of the complex Poincaré group in the case when the complex mass of the “particle” is equal to zero.

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Several new solutions of the gravitational field equations for space filled with matter are given. They are obtained under the following assumptions: (a) spherically symmetric distribution of a perfect fluid, (b) static gravitational field, (c) canonical Schwarzschild coordinates. These assumptions are the same as in the two preceding parts of the work; the procedure of deriving the solutions is modified to the extent that instead of dealing with one differential equation for one unknown function we have to deal with two such equations. Only those solutions are presented which have such a simple form that a study of general features of relativistic stellar models may be easily performed with their help. Some of the solutions (being of an especially simple form) are examined in more detail; asymptotic equations of state of the ultrarelativistic matter in the central region of highest density are given.

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The assumption of antiquark–quark scattering dominance in the formation of the secondary maximum in angular distribution is applied to photoproduction processes. The SU(6) quark model is used to obtain simple relations between the differential cross-sections for scalar and vector meson photoproduction in the momentum transfer region in which the secondary maximum appears. A qualitative explanation of the difference between the angular distributions of \(\pi ^0\) and \(\eta \) photoproduction on protons is presented.

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A discussion of the methods of energy measurement of gamma-quanta and electrons is given basing on results of a systematic investigation of the electron–photon propagation process in matter. Typical of gamma and electron shower counters are presented.