Study of η′→ηπ+π− Dalitz plot

Abstract The Dalitz plot of the η ′ → η π + π − decay is studied using the data collected with the VES spectrometer in two different exclusive reactions, π − p → η ′ n (charge-exchange) and π − N → η ′ π − N (diffractive-like production). The η mesons from η ′ decays were detected in the η → γ γ mode. The coefficients for the matrix element squared decomposition are measured on the largest statistics of η ′ decays reported so far; there are ∼ 13.6 × 10 3 and ∼ 6.5 × 10 3 decays after background subtraction in charge-exchange and diffractive-like production, respectively.