PUB - Publikationen an der Universität Bielefeld

Padé approximants are expected to probe the singularity structure of scattering amplitudes. We apply Padé approximants for Legendre series to [pi]N amplitudes, which are obtained from phase shifts. The imaginary parts were calculated from the phase-shift analysis of Almehed and Lovelace, the real parts from fixed-t dispersion relations directly and from the phase-shift analysis of Nielsen and Oades. For all amplitudes (exept for the isospin-odd Nielsen-Oades) the poles of the Padé approximants are outside the region of analyticity in the Mandelstam plane. The Padé approximants and the truncated Legendre series for the imaginary parts deviate from each other only up to 1% even close to the boundary of the double-spectral function (except for B (+)).