Partial-wave analysis of the 3π system produced in the reaction π+p → (π+π+π−)p at 8, 16 and 23 GeV/c

1974 
Abstract A partial-wave analysis has been made of the (3π) system produced in the reaction π + p → ( π + π + π − )p at 8, 16 and 23 GeV/ c using the Illinois partial-wave analysis program. The (3π) systems is in about 93% of the cases in the unnatural spin-parity states 0 − , 1 + , 2 − and 3 + and is produced in about 100% of the cases by natural parity exchange. For all J P states, the differential cross section d σ /d t ′ peaks at small tt ′, except for 2 + D which has a dip at t ′ ≈ 0. The cross sections for J P = 1 + , 2 + and 2 − in the A 1 , A 2 and A 3 regions, respectively, all have similar energy dependence, p lab − n , with n = 0.3 ± 0.2. The weak variation of the 1 + S phase across the 1.0–1.2 GeV mass region, suggests that A 1 cannot be considered as a single resonance, while the phase variation of 2 + D (ϱπ) in the A 2 mass region is consistent with resonance behaviour. In the A 3 region, the behaviour of the 2 − S and 2 − P phases is complex and further work is needed to understand the mechanisms involved there.
    • Correction
    • Source
    • Cite
    • Save
    • Machine Reading By IdeaReader
    10
    References
    29
    Citations
    NaN
    KQI
    []