Interpretation of theκinK+p→Kπππp

Abstract

The $K\pi$ mass distribution in the reaction $K^{+}p\to K\pi \pi \pi p$ was computed using a triangle graph. A singularity of the triangle diagram is manifested as a peak in the mass spectrum at a $K\pi$ mass of slightly less than the $K^{*}\pi$ mass difference. A fit to the data at 3.0 GeV/c is obtained using a $p$-wave background constant interfering with the triangle amplitude. Some features which favor this description of the $\kappa$ over a resonance explanation are (1) the absence of the $\kappa$ bump in three- and four-body final states; (2) its isotropic production distribution; (3) the lack of $\kappa N^{*}\pi$ events; and (4) the decreasing magnitude of the peak with increasing incident energy. Two suggestions are made for further experimental analysis. Firstly, a study of the above reaction at energies lower than 3.0 GeV/c is predicted to show a similar $\kappa$ enhancement (while at higher incident energies a diminution is anticipated). Secondly, the $K\pi \pi \pi$ mass distribution in the same five-body final state is predicted to show an enhancement at about 1080 MeV.