Backward pion-nucleon scattering

Abstract

A global analysis of the world data on differential cross sections and polarization asymmetries of backward pion-nucleon scattering for invariant collision energies above 3 GeV is performed in a Regge model. Including the $N_α$, $N_γ$, $Δ_δ$ and $Δ_β$ trajectories, we reproduce both angular distributions and polarization data for small values of the Mandelstam variable $u$, in contrast to previous analyses. The model amplitude is used to obtain evidence for baryon resonances with mass below 3 GeV. Our analysis suggests a $G_{39}$ resonance with a mass of 2.83 GeV as member of the $Δ_β$ trajectory from the corresponding Chew-Frautschi plot.

12 pages, 16 figures