Proton-$\hat{I}{\cdot }^{\prime }$ interactions at threshold

Abstract

Recent data on photoproduction of $\hat{I}{\cdot }^{\prime }$ mesons off protons have been included in the data base for the Bonn-Gatchina partial wave analysis. The real and imaginary parts of the $S$-wave $\hat{I}{\cdot }^{\prime }p\to \hat{I}{\cdot }^{\prime }p$ scattering amplitude in the threshold region were fit to yield the $\hat{I}{\cdot }^{\prime }p$ scattering length and the interaction range. This new analysis found $|a_{\hat{I}{\cdot }^{\prime }p}|=(0.403\pm 0.015\pm 0.060)$ fm and a phase $\ddot{I}•=(87\pm 2{)}^{\circ }$, while the range parameter is not well-constrained. The striking behavior of the GRAAL data on the beam asymmetry in the threshold region suggests that a narrow proton-$\hat{I}{\cdot }^{\prime }$ resonance might exist. However, the scattering length was found to be relatively insensitive to the possible existence of this narrow resonance.

5 pages, 5 figures