ETA-N S-WAVE SCATTERING LENGTH IN A 3-COUPLED-CHANNEL, MULTIRESONANCE, UNITARY MODEL

The S-wave scattering length for the eta N elastic scattering is extra cted from the S-wave T matrix in a three-coupled-channel, multiresonan ce unitary model. Results are compared with values already reported in the literature which are obtained on the basis of simpler models, usu ally single-resonance-no background. The dispersion among the previous ly published values of the real part of the S-wave scattering length i s observed. We show that the eta N scattering length value obtained in single-resonance-no background models significantly increases if a ba ckground term is added in a unitary way. We question the reliability o f previously reported values based only on the single-resonance-no bac kground models, and demonstrate that the value of the eta N S-wave sca ttering length obtained in this publication is much more realistic bec ause of the multiresonance and unitary approach.