Spin-Parity Analysis Of 3pi Decays In A2 Meson Region

A dalitz plot with 600 events in the A 2 mass region has been obtained at 7 GeV/ c in the reaction π − p→ →pA 2 s − , where A 2 − → π + π − π − , using a system of wire spark chambers in connection with the CERN -Missing-Mass Spectrometer. A spin parity analysis shows that for the overall A 2 region (1260< M <1360 MeV) J P =2 + is favoured P ( Ξ 2 )=40% over 1 − , 1 + , 2 − p (all with P ( Ξ 2 ) < 0.5%). When the A 2 region is divided into A 2 high and A 2 low as suggested by the missing mass spectrum, the distributions still favour 2 + over 1 − , particularly for A 2 low .