Extracting the complex energy of broad resonances by the S-matrix pole method

Abstract

A new method is proposed for finding the resonance parameters of a nuclear system, obtained from the phase shift analysis of elastic scattering data, by means of a pole representation of an S-matrix in complex momentum space is proposed. This method is based on the expansion of the potential phase shift into a Taylor series within the area of real momentum near the resonance pole. The coefficients of the expansion and resonance parameters are determined by fitting the analytical expression for the experimental phase shift. The proposed method provides reliable values of the energy and width of broad resonances.