arXiv subjects

V. A. Knyr

Publications and source records attributed to V. A. Knyr.

5 recordsLinked to original sources

arXiv2007

Nucleon-nucleon wave function with short-range nodes and high-energy deuteron photodisintegration

We review a concept of the Moscow potential (MP) of the $NN$ interaction. On the basis of this concept we derive by quantum inversion optical partial potentials from the modern partial-wave analysis (PWA) data and deuteron properties. Point-form (PF) relativistic quantum mechanics (RQM) is applied to the two-body deuteron photodisintegration. Calculations of the cross-section angular distributions cover photon energies between 1.1 and 2.5 GeV. Good agreement between our theory and recent experimental data confirms the concept of deep attractive Moscow potential with forbidden $S$- and $P$-states.

nucl-th↗

arXiv2006

Application of the $J$-matrix Method to Faddeev-Merkuriev equation: beyond pseudostates

A version of the $J$-matrix method for solving numerically the three-body Faddeev-Merkuriev differential equations is proposed. This version allows to take into account the full spectrum of the two-body Coulomb subsystem. As a result, a discrete analog of the Lippmann-Schwinger equation is obtained which allows to interpret correctly the three-body wave function in two-body domains. The scheme is applied to calculations of the fully resolved absolute differential cross sections for the He$(e,2e)$He$^+$ and He$(e,3e)$He$^{++}$ reactions at small energy and momentum transfers. The results are in good agreement with the experiment both in shape and in absolute value.

physics.atom-ph↗

arXiv2005

Reconstruction of the optical potential from scattering data

We propose a method for reconstruction of the optical potential from scattering data. The algorithm is a two-step procedure. In the first step the real part of the potential is determined analytically via solution of the Marchenko equation. At this point we use a diagonal Padé approximant of the corresponding unitary $S$-matrix. In the second step the imaginary part of the potential is determined via the phase equation of the variable phase approach. We assume that the real and the imaginary parts of the optical potential are proportional. We use the phase equation to calculate the proportionality coefficient. A numerical algorithm is developed for a single and for coupled partial waves. The developed procedure is applied to analysis of $^{1}S_{0}$ $NN$, $^{3}SD_{1}$ $NN$, $P31$ $π^{-} N$ and $S01$ $K^{+}N$ data.

quant-ph↗

arXiv2004

Reconstruction of the optical potential in the inverse quantum scattering. Application to the relativistic inelastic NN scattering

The numerical algorithm of the inverse quantum scattering is developed. This algorithm is based on the Marchenko theory, and includes three steps. The first one is the algebraic Pade approximation of the unitary S-matrix, what is realized by solving a system of linear equations. Second step is the exact solution of the Marchenko equation. The used approximant reduces it to another system of linear equations. At this step we get the real-valued potential. It is shown numerically that the developed algorithm is able not only to generate the given S-matrix dependence, but converges to the initial potential. At third step we construct the optical complex-valued potential which gives the needed S-matrix. It is shown that the modern phase shift analysis data allow to construct the nucleon-nucleon optical potentials of two kinds. These potentials describe the deuteron properties and the phase shift analysis data up to 3 GeV and they have different behavior at short distances. One is a repulsive core potential and another is a Moscow attractive potential with forbidden states.

nucl-th↗

arXiv1997

Bremsstrahlung of 350--450 MeV protons as a tool to study $NN$ interaction off-shell

The $pp\to ppγ$ bremsstrahlung cross section is calculated within the method of coordinate space representation. It is shown that in the beam energy range of 350--450~MeV a deep attractive NN-potential with forbidden states (Moscow potential) and realistic meson exchange potentials (MEP) give rise to the cross sections that differ essentially in shape: the cross sections nearly coincide in the minima but differ by a factor of 5 approximately in the maxima. Therefore, the $pp\to ppγ$ reaction at energies $\sim$350--450~Mev can be used to study $NN$ interaction off-shell and to discriminate experimentally between MEP and Moscow potential.

nucl-th↗