Study of the reactions K + p→K * N * at 3.5 and 5 GeV/cat 3.5 and 5 GeV/c

From a study of the four-body final state K+p→KNππ at 3.5 and 5 GeV/c it is found that the quasi-two-body reaction K+p→K*(892)N*(1236) is produced in large amount. This reaction shows the same general behaviour as obtained at 3 GeV/c: sharply peaked production angular distributions suggesting peripheralism as the mechanism of production. The experimental angular distributions are compared with the predictions of three models:a) one-pion exchange with arbitrary form factors,b) absorption with pion exchange,c) simple Reggepole exchange. The results show that the absorption model with π exchange predicts the shape for the production angular distribution reasonably well but less well the energy dependence of the production cross-section. It predicts rather well the general trend of the density matrix elements characterizing the decay distributions. It also succeeds in accounting for the experimental angular correlations between the K* andN* decay. The simple Regge-pole exchange gives acceptable results for both the shape and energy variation of the production angular distributions. The observed K*(1400)N*(1236) reaction at 5 GeV/c gave production and decay distributions in qualitative agreement with a 2+ K*(1400) produced in a π exchange process.