Resonance in theΛπSystem

Abstract

The reaction K/sup -/ + p -- LAMBDA /sup o/ + pi /sup +/ + pi /sup -/- was studied using 1.15-Bev/c K/sup -/ mesons in a 15-in. H/sub 2/ bubble chamber; of the total 255 events found, 141 were chosen to represent the reaction although 10 to l5% of them are estimated to be actually SIGMA /sup 0/ events. The energy distribution of the two pions on a Dalitz plot shows a nonuniform distribution of the points with peaks near 285 Mev. This distribution is consistent with a quasi-two-body reaction of the type K/sup -/ + p -Y*/sup s + pi ? (1), where Y* has a mass spectrum peaking at approximately 1380 Mev and breaks up in this way Y* plus or minus -- LAMBDA /sup oo/ + pi approximately ; 59 Y*+ /s++>s and 82 Y*/sup -/ events were observed, using the criterion that the high-momentum pion is the pion from reaction (1). Production angular distributions for Y*/sup +/ and Y*/sup -/ in the K-p rest system are given. An attempt was made without success to determine the spin of Y* by analyzing its angular momentum, the relations between its decay angle and the polarization of themore » resulting LAMBDA , and its anisotropy. The possibility that Y* corresponds to a resonance in pionhyperon scattering was studied by fitting a p-wave resonance formula to the pi LAMBDA data; the results were compared with those of Gell-Mann and Watson for the 3-3 resonance and found to be similar. (D.L.C.)« less