and background in scattering
Irkutsk State University, K. Marks Str. 1, 664003, Irkutsk, Russia
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We suggest a simple analytical description of the S-wave isoscalar amplitude, which corresponds to a joint dressing of the bare resonance and background contributions. The amplitude describes well the experimental data on the phase shift in the energy region below 900 MeV and has two poles in the half-plane. Besides the well-known pole of the -meson with , there exists a more distant pole with . Our analysis is interpreted as an indication for the dynamical origin of the pole, while the second pole should be associated with lowest state.
© Società Italiana di Fisica and Springer-Verlag, 2004