abstract

A modified version of the model of cumulative particle production in hadron–nucleus interactions based on the mechanism of nucleons “gathering” into hadronic compound-system is presented. The model results are compared with the new experimental data. A connection of the compound-system formation characteristics with the confinement of colour charges is considered.

abstract

Analytic expressions without free parameters that describe the available experimental data on the \(g\)-particle mean multiplicities in the interactions of high-energy protons, antiprotons, pions and kaons with nuclei, are obtained. The comparison with available experimental data was made.

abstract

The kinematical groups, classified by Bacry and Levy–Leblond (J. Math. Phys. 9, 1605 (1967)), are extended to the supersymmetric ones with one Majorana bispinor generator. The problem of the positive definiteness of the norm in the representation space of the introduced supergroups is discussed.

abstract

Initial results of a new Monte Carlo simulation scheme for jet evolution in perturbative QCD, taking into account soft gluon interference effects, are reviewed. When combined with a hadronization model based on the preconfinement and phase-space decay of colour-singlet clusters, the approach is in good agreement with a wide range of data on jet properties in \(e^+e^-\) annihilation and hard hadron collisions.

abstract

It is shown that the discrepancies between experimental data and current algebra calculations of Ke\(_4\), \(\eta \to 3\pi \) and \(S\)-wave \(I = 0\) pion–pion scattering length done by Weinberg and others, are due to the neglect of the unitarity and analyticity in the \(S\)-wave \(I = 0\) pion–pion channel (final state interaction).

abstract

A method of determining the formation zone by measurement of absorption of the medium-energy hadrons created in nuclear matter is outlined. It is applied to recent data on the process \(\pi ^-\to A \to \overline p+X\) and used to estimate the formation zone of \(p\) at \(\sim 16\) GeV/\(c\).

abstract

Equations of motion of relativistic perfect fluid subject to Bjorken’s boost-invariant conditions are analysed. General relations between the gradient of temperature and the shape of stream lines are derived. The case of pure transverse motion (vanishing radial velocity) is studied in some detail. It is shown that the stable solution exists only for a very restricted class of the equations of state of the fluid.

abstract

We obtain the leading asymptotic components of the Maxwell field at null infinity. Using these asymptotic expressions we derive the formula for the total action of the electro-magnetic field in terms of the residue of the Fourier amplitude of the field at zero frequency.

abstract

The four-body \(J = 0\) and \(T = 0\) or \(T = 2\) interacting term was explicitly introduced into the shell-model pairing Hamiltonian for nuclei whose protons and neutrons fill up the same harmonic oscillator shell. Due to the quasi-spin symmetry SO(5) the Hamiltonian was analytically diagonalised for one \(j\)-shell and it was also applied to the schematic two-level model sd-f\(_{7/2}\). It was found that even the small admixture of the four-body interaction provides a possibility for theoretical description of the excited 0\(^+\) levels for nuclei with \(A \geq 40\). State vectors obtained by diagonalisation were then used for transfer probability calculations leading to comparison of the probabilities of the cluster and step by step transfer reactions. The predicted new “four-body superfluidity” could be interpreted as a background for a possible two-paired boson “abnormal state” within Interacting Boson Model.

abstract

Neutron registration efficiency in experiments on muon-catalysed fusion reaction \(tt\mu \to ^4\)He\(+2n+ \mu ^-\) and \(dt\mu \to ^4\)He\(+n+\mu ^-\) is calculated. The dependence of light output response of the detectors on energy threshold of the registration apparatus is obtained. For fusion reaction in the \(tt\mu \) molecule the values of registration efficiency are determined for several types of final-state interaction between the reaction products.

abstract

Formulae describing the kinetics of muon-catalysed fusion \(t+t\to ^4\)He\(+2n\) in pure tritium are analysed with the aim of establishing optimum conditions for the experimental investigation of \(tt\mu \)-fusion. It is shown that to determine the parameters characterizing \(tt\mu \)-fusion in an experiment with a pure tritium target data have to be taken at different target densities. The range of variation of target density required to cover the region of parameter values predicted theoretically is determined. In particular, it is shown that temperature variation of the density of liquid tritium in a rather small range above the temperature of liquid hydrogen (20.4 K) is sufficient in this kind of experiment.