Antibound poles in cutoff Woods-Saxon and in Salamon-Vertse potentials

The motion of l=0 antibound poles of the S-matrix with varying potential strength is calculated in a cutoff Woods-Saxon (WS) potential and in the Salamon-Vertse (SV) potential, which goes to zero smoothly at a finite distance. The pole position of the antibound states as well as of the resonances depend on the cutoff radius, especially for higher node numbers. The starting points (at potential zero) of the pole trajectories correlate well with the range of the potential. The normalized antibound radial wave functions on the imaginary k-axis below and above the coalescence point have been found to be real and imaginary, respectively

Shell model in the complex energy plane and two-particle resonances

An implementation of the shell-model to the complex energy plane is presented. The representation used in the method consists of bound single-particle states, Gamow resonances and scattering waves on the complex energy plane. Two-particle resonances are evaluated and their structure in terms of the single-particle degreees of freedom are analysed. It is found that two-particle resonances are mainly built upon bound states and Gamow resonances, but the contribution of the scattering states is also important.Comment: 20 pages, 9 figures, submitted to Phys.Rev.

Shell Model in the Complex Energy Plane

This work reviews foundations and applications of the complex-energy continuum shell model that provides a consistent many-body description of bound states, resonances, and scattering states. The model can be considered a quasi-stationary open quantum system extension of the standard configuration interaction approach for well-bound (closed) systems.Comment: Topical Review, J. Phys. G, Nucl. Part. Phys, in press (2008

The least-squares fit of highly oscillatory functions using Eta-based functions

© 2020 Elsevier B.V. In this paper we examine the possibility of using the Eta functions as a new base for high quality approximations of oscillatory functions with slowly varying weights. We focus on the least squares and piecewise least squares approximation of such functions and compare the results obtained by using Eta-based sets of functions with those obtained by means of the Legendre polynomials and Fourier series. We find out that the accuracies from these are more or less equivalent for small frequencies but they exhibit different behaviors when the frequency is increased: the accuracy worsens for the Legendre polynomials and Fourier series base but it remains bounded for the new base, in accordance with the known properties of the Eta functions. Such an advantage makes the new base quite attractive for being used in many other mathematical contexts where highly oscillatory functions are involved

High performance computation and numerical validation of e-collision software

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