abstract

The familiar analogy, appearing in the quantum theory, between the time evolution of an isolated system and the thermal equilibrium of a system with a thermostat, is taken at its face value. This leads us to the phenomenological conjecture that, in reality, the so called isolated system may remain in a “temporal equilibrium” with the physical space-time which plays then the role of a “chronostat” defining time equal at all space points (in a Minkowski frame of reference). Such a conjecture suggests virtual deviations from this equilibrium and so seems to imply an extension of the first law of thermodynamics as well as of the state equation in the quantum theory.

abstract

A relatively simple analytical formula is derived for the energy spectrum of \(W\) boson in top quark decays \(t \to Wb\) including \(\mathcal {O}(\alpha _s)\) radiative corrections. We discuss the accuracy of this formula and compare it to a more general albeit more complicated one derived in (A. Czarnecki, M. Jeżabek, J.H. Kuhn, Acta Phys. Pol. B20, 961 (1989); (E) B23, 173 (1992)). A Monte Carlo algorithm for generation of \(W\) energy spectrum is briefly described.

abstract

The static energy of the baryon number \(B = 2\) SO(3) soliton calculated within the framework of the Chiral Quark Model is interpreted as a mass of a dibaryon six quark state. The calculated mass is of the order of 3 GeV and therefore dilambda lies above the physical threshold for two \(\Lambda \) decay. It is however argued that if the threshold itself is calculated within the same model dilambda mass is slightly below the mass of two \(\Lambda \). This is due to the fact that the chiral models overestimate total masses usually by a few hundred MeV.

abstract

A microscopic model based on a molecular dynamics concept is presented. The model simulates some quantum effects and thus enables studies of large fermionic systems. It was devised to investigate the dynamics of heavy ion collisions at intermediate energies. The model was applied to study an early phase of the \(^{84}\)Kr + \(^{159}\)Tb reaction at 45 MeV/nucleon.

abstract

We have calculated relativistic corrections to one-nucleon levels of \(^{208}\)Pb in the first approximation of the perturbation theory for the mass and potential energy in the Woods–Saxon potential case. We have obtained corrections for the mass increase for the large principal or orbital quantum numbers. The corrections for the mass in the state 1\(s_{1/2}\) are \(-\)0.0087 MeV for neutrons and \(-\)0.0097 MeV for protons. Corrections \(-\)0.6788 MeV for neutrons and \(-\)0.5884 MeV for protons for the excited states 1\(j_{15/2}\) and 1\(i_{13/2}\) are comparable with the energy of these levels. Corrections for the potential stay small for all states. Including the relativistic corrections for mass we have obtained a better correlation between theoretical and experimental levels of energy for the excited states.

abstract

The properties of the base functions resulting from the solutions of fermionic Hamiltonian possessing unitary symmetry are analyzed. The attention is focused on the solutions of nuclear cranking model Hamiltonian in a single \(j\)-shell space. It appears that, in this case, the group theoretical treatment offers a lot of simplifications as compared to any other method. In particular, we analyze the properties of the base functions under the signature symmetry transformation proving that signature is sharply defined inside each irreducible representation.

abstract

To understand the mechanism of neutron energy deposition in uranium-scintillator calorimeters a fast Monte Carlo code has been developed to simulate the behaviour of neutrons with energy below 20 MeV. The code predictions are compared to experimental measurements. Some comments are drawn on the size of the signal produced by neutrons and their contribution to the energy resolution of uranium calorimeters with hydrogenous readout.

abstract

The influence of an electron bound to a fast light ion on the impact parameter dependent electronic energy transferred in a single collision to a neutral atom was calculated within the perturbation formalism, using sum rules. The random stopping power, calculated analytically from this theory was shown to have the Bethe form. Analytical results were obtained for the dipole approximation. The present results were compared with other theoretical results.