abstract

Fundamental limitations of the identical particle correlations method, used for the determination of the source size are discussed. It is shown that the limitations are in each case determined by quantum-mechanical characteristics of the method used for particle registration. For the case of track detectors the upper limit of the source sizes which can be determined by the study of correlations does not exceed the atomic size.

abstract

The stroboscopic maps technique is applied to a model of the dynamics of a single haploid population with a natural selection in a fluctuating environment (genetic model). The stochastic perturbation is replaced by a deterministic chaotic system which — in a certain limit — has properties of a white noise generator. First, the white noise limit is discussed and tested using various statistical methods. The transition from the deterministic chaotic behaviour to the stochastic one, depending on the time scales separation is discussed. We also discuss the results of using different underlying chaotic dynamics on the macroscale properties, especially Lyapunov exponents and dimensions. The paper forms a revision and a substantial extension of [1].

abstract

Gravitational interaction responsible for stability of large objects like stars and planets results in their mass-defect, thus affecting the gravitational “coupling constants”. This double role of gravitation leads to the non-extensive character of mass, which would question the locality of gravitational field equations in the regions filled by matter.

abstract

The equations of motion yielding the Van-der-Waarden form of the Dirac free-field theory in complex Minkowski space are actually derived by working out a variational principle that involves a manifestly two-spinor Lagrangian density. We make use of this Dirac Lagrangian density to build up a suitable defining relation for the energy-momentum tensor of the theory which gives rise at once to a set of essentially equivalent expressions for the tensor. In particular, it is shown that one of the structures arising from our definition coincides with the well-known Penrose expression up to a conventional overall sign. A set of new covariant contour integrals for the corresponding energy momentum four-vector and angular-momentum bivector is exhibited. We then show that the entire set of spinor formulae affords us another method of establishing the relevant charge-conservation statement.

abstract

In a version of the standard model the Higgs boson is replaced by a doublet \((B^+, B^0)\) of vector bosons, and the masses of gauge bosons and fermions are generated by the dynamical breaking of the gauge group. In this note it is shown that \(B^+\) and \(B^0\) are heavy particles: \(m_{B^+} \approx 0.9m_{B^0}\), \(m_{B^0} \gtrsim 42.73\) GeV. Production of \(B\) particles i  studied in \(e^+e^- \to B^0 \overline {B^0}\), \(B^+B^-\), \(ZB^0 \overline {B^0}\), \(ZB^+B^-\). In particular, \(B^0 \overline {B^0}\) has a large cross section in \(Z\)-resonance region. The \(B^+B^-\) production is a factor of \(\cos ^22\theta _W\) smaller than that of \(B^0 \overline {B^0}\).

abstract

It is argued that quarks immersed in the magnetic vacuum, though asymptotically free, are strongly coupled to gluons and share with them appreciable fraction of their momenta. This effect might be qualitatively related to the known nonperturbative property of the nucleon structure function: equal sharing of the nucleon momentum between quarks and gluons.

abstract

Following the idea that the phenomenon of intermittency is related to HBT correlations between identical pions, we investigate the origin of the power law behaviour of the correlation functions. The measurements of the higher-order correlation functions indicate that the observed intermittency is an effect present in individual events rather than the result of incoherent superposition of many events. Also uncorrelated emission from a space-time volume of any shape does not seem to account for the data. These results suggest a genuine fractal space-time structure of particle production.

abstract

The Thomas–Fermi model is used to calculate the equation of state (EOS) for nuclear as well as neutron matter. We apply the effective nucleon-nucleon interaction of Myers and Swiatecki which is velocity and density dependent. The calculations cover a wide density range of interest in heavy-ion collisions and astrophysics. We explore the thermodynamical behaviour of symmetric nuclear matter and neutron matter at finite temperature as it results from our EOS. As an illustration, the maximum stable mass of neutron star is calculated.