Pion diffraction dissociation into five pions at 16 GeV/c

Abstract In π ± p interactions at 16 GeV/ c , evidence is obtained for the existence of the diffractive dissociation of the pion into five pions ( π → 5 π ), and possibly also for π → 7 π , on the basis of the Feynman x distribution of the slowest pion. Cross sections for the five-pion diffractive component are estimated for the π + and the π − experiments using two methods. In a selected event sample characterized by the dominance of diffractive production of five-pion systems, an average ϱ 0 (770) multiplicity of 1.75 ± 0.20 was measured, indicating ϱ 0 ϱ 0 π contributions in at least 75% of the events. The slope of the four-momentum transfer distribution of the five-pion systems was found to be similar to that of diffractively produced three-pion systems of the same mass. The results are compared with those reported for five-pion systems coherently produced on a deuteron target.