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🗀 Archive 2010-2015

Department of Theory of Nuclei and Quantum Field Theory

- We study the influence of a background magnetic field and boundary conditions on the vacuum of a quantized charged spinor matter field in a bounded space. It is found that, in the case of a sufficiently strong magnetic field directed orthogonally to two parallel bounding plates, the Casimir force is independent of a boundary condition, as well as of the distance between the plates.
*Yu.A. Sitenko* - New analytical expressions for the p-, d- and f-wave partial two-body Coulomb transition matrices at the energy of the ground bound state of the complex have been derived. The obtained results have been used for studies of the properties of few-body atomic and nuclear systems.
*V.F. Kharchenko* - By making use of the recommended proton-proton low-energy interaction parameters the following value for the charged pion-nucleon coupling constant has been obtained. The calculated value of this quantity appears to be in excellent agreement with the experimental result of the Uppsala Neutron Research Group.
*V.A. Babenko, N.M. Petrov*

- We establish relationship between the physical quantities that characterize charge symmetry breaking of nuclear forces in the two- and three-nucleon systems. The treatment is based on the analysis of the difference between the binding energies of mirror nuclei
^{3}H and^{3}He. By making use of the singlet "nuclear" proton-proton scattering parameters we obtain the following values for the neutron-neutron scattering length and effective range: a_{nn}=-18.38(55)fm, r_{nn}=2.84(4)fm. Calculated values of these quantities appear to be in reasonable agreement with the experimental results.*V.A. Babenko, N.M. Petrov* - The quantum-mechanical theory is developed for the case of scattering of non-relativistic particles with spin on permeable magnetic vortices.
*Yu.A. Sitenko* - A new efficient approach to description of electric polarization of a quantum bound system has been developed that is based on introducing a special scattering function off the energy shell. This method has been applied to determination of electric polarizabilities of few-body atoms and nuclei.
*V.F. Kharchenko* - On the basis of strict equations of quantum geometrodynamics for the homogeneous and isotropic universe, the possible cause of change of the rate of the expansion of the universe, from deceleration to acceleration and vice versa, is given. It is shown that the dark sector of the matter-energy may point to the existence of previously unknown forces acting in the universe, whose nature is quantum. The model explains the accelerating expansion (inflation) in the early universe and a later transition from the decelerating expansion to the accelerating expansion of the universe from a single approach. It is demonstrated that the change of sign of the quantum correction to the pressure generates primordial fluctuations of the energy density.
*V.E. Kuzmichev, V.V. Kuzmichev*

- A possibility of the generation of a magnetic field by a cosmic string appearing in the aftermath of the deconfinement-confinement phase transition in early Universe is considered. We find the theoretical estimates of the magnetization of the surrounding plasma owing to its interaction with the magnetic field of the cosmic string.
*Yu.A. Sitenko* - Based on the quantum T-matrix formalism for description of the interaction of a charged particle and a complex, the inhomogeneous integral Lippmann-Schwinger equation with the Coulomb interaction that takes consistently virtual multiple scattering into account has been analytically solved and the general formula for all the electric multipole polarizabilities of the hydrogeh-like atom has been derived.
*V.F. Kharchenko* - The influence of the mass difference between charged and neutral ?-mesons on the low-energy characteristics of nucleon-nucleon interaction in the
^{1}S_{0}spin-singlet state was studied within the framework of the effective-range approximation. By making use of the latest experimental results on the nd breakup reaction we obtain the following values for the neutron-neutron scattering length and effective range: a_{nn}=-16.59fm, r_{nn}=2.83fm.*V.O. Babenko, M.M. Petrov* - Model of an Ohmic contact as a piece of metal of the finite capacitance attached to a quantum Hall edge was proposed. It is shown that charged quantum Hall edge states may have weak coupling to neutral excitations in an Ohmic contact.
*I.P. Levkivskyi*

- Quantum-mechanical theory of scattering of a charged particle by a magnetic vortex with its transverse size taken into account has been elaborated. We show that the propagation of short-wavelength, almost classical, charged particles can be controlled by altering the flux of the magnetic vortex which is perpendicular to the direction of the particle motion. An experiment to verify the Aharonov-Bohm effect in scattering of quasiclassical particles is proposed.
*Yu.A. Sitenko, N.D. Vlasii* - A new microscopic approach to the description of the deformation of quantum (atomic and nuclear) bound systems in the electric field that is based on the direct solution of the Lippmann-Schwinger, Faddeev or Faddeev-Yakubovsky equations for the transition matrix has been formulated.
*V.F. Kharchenko* - In the framework of the study of the early universe based on the standard cosmological model, it is shown that the principle of inertia on the stage of decay of vacuum-like state of inflaton field into ordinary particles is equivalent to the law of conservation of the total energy of the universe, which vanishes due to the gravitational mass defect. Implementation of this law which has a form of constraint in the Einstein field equations leads to the fact that matter before reheating is a perfect gas of low-velocity cosmic strings. Then this gas heats up and takes the form of radiation.
*V.E. Kuzmichev, V.V. Kuzmichev* - Low-energy effective range parameters of neutron-proton scattering are calculated on the basis of the latest experimental data on phase shifts of np-scattering from the SAID nucleon-nucleon database (data of the GWU group). The obtained effective range parameters corresponding to the experimental data from the SAID database lead to an extremely well description of experimental total cross section of neutron-proton scattering.
*V.A. Babenko, N.M. Petrov*

- We have studied polarization of the vacuum of a quantized scalar field which is subject to the Dirichlet condition at the boundary of an impenetrable magnetic vortex. It is shown that the vacuum energy is induced in the case when the Compton wavelength associated with the scalar field exceeds considerably the vortex thickness; the amount of the vacuum energy depends periodically on the vortex flux.
*Yu.A. Sitenko* - Total cross section of neutron-proton scattering at zero energy σ
_{0}was calculated using the data on total cross sections in the energy region 0-150 keV. The obtained value of the cross section is in very good agreement with the experimental cross sections of Houk and Hurst, but contradicts to the experimental cross section of Dilg.*V.A. Babenko, N.M. Petrov*