Analyzing-power measurement in p

We have measured analyzing powers in {ital d}({ital {rvec p}},{pi}{sup {minus}}pp)p at a beam energy of 400 MeV and laboratory pion detector angles of 35{degree} and 43{degree}. The {pi}{sup {minus}} and two of the outgoing protons were detected in coincidence in a geometry which selected the quasifree two-body reaction {ital pn}{r arrow}{pi}{sup {minus}}pp({sup 1}S{sub 0}). The analyzing-power data combined with {sup 3}He({pi}{sup {minus}},{ital pn}){ital n} differential cross sections allow determination of the transition amplitudes. The results indicate a significant contribution from a very short-range part of the nucleon-nucleon interaction.