Partial-wave analysis of backwardly produced three-pion systems in K−p interactions at 4.2 GeV/c

We report on the results of a partial-wave analysis of the 3π system produced by baryon exchange in the reaction K−p→Σ−π+π+π− at 4.2 GeV/c. We confirm the existence of an enhancement in the 1+S(ϱπ) wave as previously established from a Dalitz plot analysis of the same data. The phase variation of this wave is found to be consistent with that expected for a resonance and thus the enhancement is identified with A1 production. No clear signal for this state is found in either the reaction K−p→Σ+π+π+π−π− or K−p→Λπ+π−π0. We also find production via baryon exchange of the A2 in all three reactions and the ω and ω∗ (1975) in the third reaction.