Study of the reaction π–A π+π–π– A at large statistics with VES setup

Partial wave analysis of the π–A π+π–π– system produced by 29 GeV/cπ– beam on a beryllium target is presented. About 30 × 106 |events in the wide t′|range 0–0.8 GeV2/c 2 are collected with upgraded VES setup. The size of the data sample is 2.5 times larger than one previously analyzed by VES. Data are analyzed using formalism of the density matrix with unlimited rank. We discuss status of the a 1(1420) a 2(1700) a 3(1875) states and a structure of exotic ρ(770)π P-wave with J PC = 1-+. Parameters of a 3(1875) are estimated as M = 1985 ± 20 MeV/c 2, Γ = 200 ± 50 MeV/c 2 (preliminary).