NIKHEF-H, Amsterdam, The Netherlands;CERN, Geneva, Switzerland;Institute of Nuclear Physics, Cracow, Poland;Max-Planck-Institut für Physik and Astrophysik, Munich, Fed. Rep. Germany
Abstract:
In partial wave analyses of the (π?π?π+) system, substantial shape changes of the 1+S (?π) intensity as a function of t, and relative phase changes of ≈ 90°, provide compelling evidence for a resonant A1 of mass ≈ 1280 MeV and width ≈ 300 MeV.