Observation of Quasi Two-Body Production in Pion Plus Proton Goes to Neutron Plus Four Charged Pions at 8 GeV/C

摘要

The first observation of quasi 2-body production in the backward reaction pi exp - p implies n pi exp + pi exp + pi exp - pi exp - is reported. Data were obtained with an 8-GeV/c pion beam incident on a liquid hydrogen target inside the University of Illinois/Argonne National Laboratory streamer chamber. The chamber was triggered by the interaction of a fast, forward neutral hadron in thick-plate optical spark chambers. Total backward cross sections were derived for the processes pi exp - p implies N* exp 0 (1520) + rho exp 0 /f exp 0 , N* exp 0 (1670) + rho exp 0 /f exp 0 , delta exp 0 (1890) + rho exp 0 /f exp 0 , and delta exp - (1236) + A sub 2+ . Evidence for a narrow A sub 1+ resonance was not seen. Corrections for losses due to finite acceptance were made by Monte Carlo techniques based on a simple baryon exchange model. Comparison is made to another experiment regarding the energy dependence of certain cross sections, and a simple power law behavior is observed. 16 figures, 8 tables. (ERA citation 05:014470)