Associate K^0 production in p+p collisions at 3.5 GeV: The role of Delta(1232)++

Abstract

An exclusive analysis of the 4-body final states $\hat{\mathrm{I}}›+\mathrm{p}+\ddot{\mathrm{I}}{€}^{+}+{\mathrm{K}}^0$ and $\hat{\mathrm{I}}{\pounds }^0+\mathrm{p}+\ddot{\mathrm{I}}{€}^{+}+{\mathrm{K}}^0$ measured with HADES for p+p collisions at a beam kinetic energy of 3.5 GeV is presented. The analysis uses various phase space variables, such as missing mass and invariant mass distributions, in the four particle event selection (p, $\ddot{I}{€}^{+}$, $\ddot{I}{€}^{+}$, $\ddot{I}{€}^{-}$) to find cross sections of the different production channels, contributions of the intermediate resonances $\hat{\mathrm{I}}{”}^{++}$ and $\hat{\mathrm{I}}\pounds (1385{)}^{+}$ and corresponding angular distributions. A dominant resonant production is seen, where the reaction $\hat{\mathrm{I}}›+\hat{\mathrm{I}}{”}^{++}+{\mathrm{K}}^0$ has an about ten times higher cross section ($29.45\pm 0.08_{-1.46}^{+1.67}\pm 2.06\hat{\mathrm{I}}¼\mathrm{b}$) than the analogous non-resonant reaction ($2.57\pm 0.02_{-1.98}^{+0.21}\pm 0.18\hat{\mathrm{I}}¼\mathrm{b}$). A similar result is obtained in the corresponding $\hat{I}{\pounds }^0$ channels with $9.26\pm 0.05_{-0.31}^{+1.41}\pm 0.65\mathrm{mub}$ in the resonant and $1.35\pm 0.02_{-1.35}^{+0.10}\pm 0.09\hat{\mathrm{I}}¼\mathrm{b}$ in the non-resonant reactions.

12 pages, 11 figures