abstract

The gauge theory of gravitation based on a quadratic Lagrangian in the tetrad Palatini formalism is developed. In the general case the theory contains torsion. The field equations without torsion generalize the field equations in Yang’s theory of gravitation. It is shown that the solutions of the exterior Schwarzschild problem and of the Friedman problem coincide completely with solutions of these problems in the Einstein theory.

abstract

In this paper the interior field of a static spherically symmetric charged fluid distribution in Einstein–Cartan theory has been studied. Assuming that the spins of the individual particles composing the fluid are all aligned in the radial direction, we have obtained a solution and the physical constants appearing in the solution have been evaluated by matching the solution to the Reissner–Nordstrom metric at the boundary. Unlike general relativity, \(p\) is discontinuous at the boundary of the fluid sphere.

abstract

Analytic solutions of the Einstein–Cartan field equations for the interior of a fluid sphere are obtained. Some of these solutions may be applicable to the investigation of stellar interiors where high central density and pressure are significant (i.e. massive bodies like non-rotating neutron stars).

abstract

It is shown that the simple non-interacting fireball model reproduces the charged particles multiplicity distribution for \(\pi ^-\)d collisions as well as more sophisticated models based on the reggeon calculus do. Much better statistical data for the highest multiplicity channels in both \(\pi ^-\)d and \(\pi ^-\)N scattering would be necessary to resolve the present ambiguity.

abstract

The existence of a sharp break in the pp elastic differential cross section is explained here on the basis of the structural aspects of proton. The differential cross section for pp scattering at 90\(^{\circ }\) is found to be in excellent agreement with the theoretical predictions made on the basis of a model of hadrons based on lepton–hadron relation satisfying duality.

abstract

We present a naive quark parton model for partons with an arbitrary transverse momentum. In our model, the average value of this momentum for nucleon constituents which contribute to the deep inelastic lepton-nucleon scattering varies with the variable x and is proportional to the difference of the structure functions, i.e. \(\left \lt k^2_{\bot }(x)\right \gt \sim F^{\rm p}_2(x)-F_2^{\rm n}(x)\).

abstract

We show that quark longitudinal degrees of freedom are important for the shape of the elastic p–p cross-section calculated in the dressed quark model using Glauber multiple scattering expansion. We find also that in this model multiple scattering terms are greater than required by data.

abstract

The diffractive dissociation of hadrons is interpreted as production of the gluonic excitations of incident particles. Regge trajectories of such gluonic excitations are calculated in the bag models and in the dual model. Good agreement is round with the observed spectra of diffractive bumps.

abstract

The quark fragmentation model is extended to describe meson and baryon production from quark as well as diquark jets. The model is applied to e\(^+\)e\(^-\) inclusive annihilation and the current and target fragmentation region of deep inelastic scattering. An independent test of the model in lepton pair triggered meson nucleon reactions is proposed. The hadron distributions are predicted to depend on \(x=\sqrt {M^2/s}\) and \(x_{\rm F}\) only via \(x_{\rm F}/(1-x)\).

abstract

The quark–parton model description of the space-time evolution of hadronic collisions is shown to lead to a two component model of dilepton production. The Drell–Yan mechanism takes into account the possible annihilations of those quarks and antiquarks which are present already in the incoming hadrons. This process is fast (operative at the beginning of the collision) and hard (long range in rapidity) and it is responsible for the production of dimuons with large masses. The second component describes the annihilations of quarks and antiquarks created during the collision. Due to the constraints imposed by the space-time evolution of the collision, only quarks and antiquarks separated by small rapidity gaps can annihilate what leads to the production of dimuons with low masses. Monte Carlo model containing both components is shown to be in good qualitative agreement with data available at FNAL energies. The \(\gamma \)- and \(p_{\rm T}\)-distributions of quarks and antiquarks entering the calculations were fixed by data on multiparticle production.

abstract

Various sets of the Woods–Saxon potential parameters are extrapolated to the \(Z = 114\) to 126 superheavy element region. It is shown that the behaviour of the single particle level density may indicate magic numbers different from those indicated simply by the appearance of energy gaps in the single particle spectrum. The possible readjustment of the nuclear skin thickness parameter is discussed in the case of protons. Deformation of the Woods–Saxon potential is introduced in terms of the \(\beta _2\) and \(\beta _4\) parameters and the resulting fission barriers are calculated together with the corresponding life-times; the relative stability of the elements with \(Z\) lower than \(Z=126\) is pointed out. The computed fission life-times for the most stable nuclei vary from \(3.0 \times 10^{+15}\) sec to \(2.0 \times 10^{+26}\) see, while the corresponding life-times with respect to \(\alpha \)-decay vary from \(2.0 \times 10^{+11}\) sec to \(9.0 \times 10^{+5}\) sec.

abstract

The hypothesis of a glory-like nature of polar emission of light charged particles in fission was investigated by means of the classical calculation of three-body trajectories. A model was studied according to which the light particle trajectories are bent towards the fission axis under the action of the Coulomb and nuclear potentials of the deformed fission fragments. The effect of the friction force was also studied. It appears that this hypothesis does not explain the considered phenomenon unless very dubious assumptions are made, concerning the diffuseness of fission fragment surface and the localisation of charged particle starting points.