Study of the reactions K+p→KπN at 735 and 785 MeV/c

Incoming K+ momenta of 735 and 785 MeV/c were chosen to study the reactions K+p→KπN below the K*(890) andN*(1236) production thresholds in the hope of observing the production of the κ-meson if it exists. A broad enhancement is observed in the (Kπ)+ mass spectrum, which could be attributed to the production of a κ-meson of mass ∼725 MeV, width ∼50 MeV and cross-section <200 μb at 785 MeV/c. A more likely explanation is offered by assuming an interference between the low-energy tail of theN*(1236) and anS-wave pπ+ background without invoking the production of κ-mesons. Simple assumptions concerning the amplitudes of theN* tail and of the pπ+ background lead to production and decay distributions in good agreement with the experimental spectra.