An important question about resonance extraction is how much resonance poles
and residues extracted from data depend on a model used for the extraction, and
on the precision of data. We address this question with the dynamical
coupled-channel (DCC) model developed in Excited Baryon Analysis Center (EBAC)
at JLab. We focus on the P11 pi-N scattering. We examine the model-dependence
of the poles by varying parameters to a large extent within the EBAC-DCC model.
We find that two poles associated with the Roper resonance are fairly stable
against the variation. We also develop a model with a bare nucleon, thereby
examining the stability of the Roper poles against different analytic structure
of the P11 amplitude below pi-N threshold. We again find a good stability of
the Roper poles.Comment: 6 pages, 8 figures, Contribution to the proceedings of 24th
International Nuclear Physics Conference (INPC), Vancouver, Canada, 4-9 July
201
