Combined analysis of meson channels with I=1, C=−1 from 1940 to 2410 MeV

Abstract

New Crystal Barrel data are reported for p ̄ p→ωπ 0 and p ̄ p→ωηπ 0 with ω decaying to π + π − π 0. The shapes of angular distributions agree well with those for data where ω→ π 0 γ; this is a valuable cross-check on systematic errors. The new data provide good measurements of vector and tensor polarisations P y , T 20, T 21 and T 22 of the ω. These lead to significant improvements in parameters of several resonances reported earlier. New values of masses and widths (in MeV) are: J PC =5 −− (2300±45, 260±75), J PC =3 −− (2260±20, 160±25), J PC =1 +− (2240±35, 320±85), and J PC =1 −− (2110±35, 230±50). A remarkable feature of the data is that vector polarisation P y is close to zero everywhere. It follows that all interfering amplitudes have relative phases close to 0 or 180°. Tensor polarisations are large.