A study of the low-mass pπ+π- system produced in the reaction K+p→K+pπ+π- between 7.3 and 16 GeV/c

Results are presented on an analysis of the reaction K+p→K+(pπ+π-). The I-spin of the low-mass pπ+π- enhancement is shown to be 1/2 and the cross section for production of pπ+π- states with mass less than 1.7 GeV is shown to be essentially independent of beam momentum. The slopes of the t distributions for various pπ+π- mass slices are determined. These results, and those from moments analyses of the pπ+π- system, are consistent with production via pomeron exchange. A partial-wave analysis, carried out with the assumption of pπ+π- production by pomeron exchange gives the contributions of the various Jsup(P) states for Δπ, pepsilon and prho decay modes of the pπ+π- system. The peak near a pπ+π- mass of 1.4 GeV is shown to be mainly Δπ in a 3/2-(L=0) state. The peak near 1.7 GeV is about 50% Δπ and 50% pepsilon. The 3/2-(L=2)Δπ and 3/2-(L=1)pepsilon states both contribute to this peak, but 5/2+(L=1)Δπ is not strong, contrary to what might be expected. (Auth.)