abstract

Exact solutions of the field equations for a thermodynamical perfect fluid with an infinite electrical conductivity and constant magnetic permeability are obtained under the assumptions that the space-time is spherically symmetric, the flow is isentropic and the fluid is incompressible. A class of static solutions reduces to the well known Schwarzschild solution in the absence of the magnetic field and Nordstrom–Jeffery type solution is recovered when the field is purely magnetic. A class of non-static and time-dependent solutions is also obtained. For numerical evaluation, the results are cast in dimensionless forms and the boundary conditions are stated.

abstract

Diffraction dissociation of pions and kaons is discussed in terms of the pomeron current model. Pomeron exchange is represented in this model by an effective current-current interaction, where the pomeron current \(V_{\mu }\) has two components \(V_{\mu }=V_{1\mu }+V_{\mu }\), the first being central and conserved and the second peripheral and nonconserved. \(V_{1\mu }\) and \(V_{2\mu }\) correspond to interactions of sea and valence quarks respectively at the diffractive vertex. We construct explicit amplitudes for N\(\pi \to \) N\(\pi \)*, NK \(\to \) NK* (\(\pi \)*, K* are resonances or partial waves of multiparticle states with any spin and parity). Two form factors (one form factor) determine the transition vertices \(\pi \to \pi \)*, K \(\to \) K* to unnatural parity (natural parity) states \(\pi \)* and K*. The model is shown to have no difficulty in reproducing the polarization observed in pion and kaon dissociation to any final state. Other properties of the model are discussed.

abstract

We point out that the mass-dependent polarization effects observed in diffraction dissociation can be attributed largely to two simple causes: (1) the increasing importance of higher partial waves with increasing final mass; (2) a kinematic suppression of helicity flip for dissociation into large-mass states. These lead respectively to (a) strong violation of \(s\)-channel helicity conservation and (b) a much weaker violation of \(t\)-channel helicity conservation for large diffractively-produced mass. This is observed experimentally. The kinematic suppression of helicity flip for large mass is a new result which we prove in this article. Recent data is discussed, and the implications of our result for the triple-pomeron vertex are mentioned.

abstract

We note the fact that doubling Lipkin’s third component \(\sum \limits _{\varrho ,\omega }(\alpha \pi /\gamma ^2{\rm v}) \sigma _{\rm tot}^{(3)}({\rm Vp})\) contributing to forward Compton scattering in the vector dominance model \(\sum \limits _{\varrho ,\omega ,\phi }(\alpha \pi /\gamma ^2{\rm v})\sigma _{\rm tot}^{(3)}({\rm Vp})\) one fully saturates \(\sigma _{\rm tot}(\gamma {\rm p})\). The result can be understood in terms of Preparata’s light cone controlled mass dispersion relations if the light cone contribution is identified with \(2\sum \limits _{\varrho ,\omega }(\alpha \pi /\gamma ^2{\rm v})\sigma _{\rm tot}^{(3)}({\rm Vp})\).

abstract

Different methods of regularization in quantum field theory are compared. It is argued that a regularization is correct if it gives the amplitude with analytical properties predicted by the Cutkosky lemma.

abstract

Investigations of angular and energetic distributions of \(\pi ^0\) mesons produced by \(\pi ^-\) mesons on xenon target have been done. It was found that the correlation between emission angles and energy of \(\pi ^0\) mesons corresponds kinematically to the emission of \(\pi ^0\) mesons from an effective intranuclear target with mass roughly equal to the mass of \(\pi \) meson. A possible influence of secondary intranuclear processes on angle and energy distributions of \(\pi ^0\) mesons is discussed.

abstract

We present a model of multiparticle production in high-energy \(h_1h_2 \to X\) collisions, based on the “bremsstrahlung” analogy and the parton model. Long range correlations in rapidity are obtained as a consequence of hadron structure.

abstract

Longitudinal phase-space is used to study the energy dependence of the plateau in the rapidity distribution of particles produced in p–p collisions at laboratory momenta above 100 GeV. The density of particles emitted at 90\(^{\circ }\) in cms shows a fast rise until 10 000 GeV and then approaches the asymptotic limit very slowly. This rise accounts for a large fraction of the experimentally observed increase.

abstract

The possibility of interpretation of anomalies in backward-angle alpha scattering is investigated in terms of the alpha-cluster exchange and one nucleon exchange. The alpha-exchange model alone is insufficient to explain the ALAS effect. Both the alpha-exchange and one nucleon exchange reproduce better the anomalies. Some information on alpha-clusters in calcium nuclei is obtained.