Comparison of Isobar Production inppandp¯nInteractions at 2.8 GeV/c

Abstract

The reactions $\mathrm{pp}\to N^{*++}\mathrm{}\left(1238\right)n$ and $\overline{p}n\to {\overline{N}}^{*--}\mathrm{}\left(1238\right)p$ at 2.8 GeV/c incident laboratory momentum are analyzed with the Brookhaven National Laboratory 20-in. bubble chamber. Isobar and anti-isobar production differential cross sections and decay angular distributions are compared with the predictions of an absorptive single-pion-exchange model. The absolute values, shapes, and ratios of the cross sections are in good agreement with the theory when the absorptive parameters ${\gamma }_1$ and ${\gamma }_2$ are 0.033 and 0.016 for the $\overline{p}n$ reaction, and 0.057 and 0.019, respectively, for the $\mathrm{pp}$ reaction.