Application of the propagator method to pair production in the Robertson-Walker metric

The method suggested earlier is applied to the problem of pair production in the Robertson-Walker universes with scale factorst , 1. The method is based on the postulate that the positive-frequency wave functions must be propagated forward in time by the causal propagator. The causal propagator is defined as the Green's function with minimal divergences on the Euclidean section of the space-time. The results for the casea(t)=t coincide with those of Chitre and Hartle. In the casea(t)=t t , <1, it is shown that the present approach predicts creation of conformal invariant massless scalar particles. It is demonstrated that the conformal transformation method gives the same predictions provided that the global properties of the space-time are taken into consideration.     

The single-channel model for the hydrogen mesic molecule fusion reaction

The scattering theory for two separated potential wells is applied to the problem of dt mesic molecule nuclear width determination within the scope of the single-channel model for nuclear particles.     

Solving Bethe–Salpeter Equation for Scattering States

We present the Minkowski space solutions of the inhomogeneous Bethe–Salpeter equation for spinless particles with a ladder kernel. The off-mass shell scattering amplitude is first obtained.     

Effect of alkanotrophic Rhodococcus strain on mechanical and structural characteristics of quartz glass

The effect of alkanotrophic Rhodococcus strain on mechanical and IR spectroscopic characteristics of highly porous quartz glass was studied.     

Present Status of the Bethe–Salpeter Approach in Minkowski Space

Recently developed methods allowing to find the solutions of the Bethe–Salpeter equations in Minkowski space, both for the bound and scattering states, are reviewed. For the bound states, one obtains the bound state mass and the corresponding BS amplitude. For the scattering states, the phase shifts (complex above the meson creation threshold) and the half-off-shell BS amplitude are found. Using these solutions, the elastic and transition electromagnetic form factors are calculated.     

Antiproton-nucleus electromagnetic annihilation as a way to access the proton timelike form factors

Contrary to the reaction \( \bar{{p}}\) p \( \rightarrow\) e ⁺ e ^- with a high-momentum incident antiproton on a free target proton at rest, in which the invariant mass M of the e ⁺ e ^- pair is necessarily much larger than the \( \bar{{p}}\) p mass 2m , in the reaction \( \bar{{p}}\) d \( \rightarrow\) e ⁺ e ^- n the value of M can take values near or below the \( \bar{{p}}\) p mass. In the antiproton-deuteron electromagnetic annihilation, this allows to access the proton electromagnetic form factors in the timelike region of q² near the \( \bar{{p}}\) p threshold. We estimate the cross-section \(d\sigma _{\bar pd \to e^ + e^ - n} /d\mathcal{M}\) for an antiproton beam momentum of 1.5GeV/c. We find that near the \( \bar{{p}}\) p threshold this cross-section is about 1pb/MeV. The case of heavy-nuclei target is also discussed. Elements of experimental feasibility are presented for the process \( \bar{{p}}\) d \( \rightarrow\) e ⁺ e ^- n in the context of the \( \overline{{{\rm P}}}\) ANDA project.     

Calculation of muon fraction stopped in the dt-cell of a 14 MeV neutron generator

The muon utilization efficiency is calculated for a model of a neutron source based on muon-catalyzed fusion, and the intensity and neutron flux are estimated in this system.     

New Universal Cosmic-Ray Knee near a Magnetic Rigidity of 10 TV with the NUCLEON Space Observatory

Data from the NUCLEON space observatory give a strong indication of the existence of a new universal cosmic ray “knee”, which is observed in all groups of nuclei, including heavy nuclei, near a magnetic rigidity of about 10 TV. Universality means the same position of the knee in the magnetic rigidity scale for all groups of nuclei. The knee is observed by both methods of measurement of particles energy implemented in the NUCLEON observatory—the calorimetric method and the kinematic method Kinematic Lightweight Energy Meter. This new cosmic ray knee is probably connected with the limit of acceleration of cosmic rays by some generic or nearby source of cosmic rays.