Study of the pionic correlations in pn → 2π+3π− annihilation at rest

Abstract The experimental 2π correlations in p n → 2π + 3π − annihilation at rest are studied as a function of the four-momentum transfer Q 2 . The distributions have maxima at Q 2 = 0 GeV 2 /c 2 with height h 2 ∼ 4 for both 2 π + and 2 π − correlations. This value is too high to be in agreement with the theory of the Bose-Einstein correlations. The experimental correlations are satisfactorily reproduced by the channel S 0 (1390) π − , S 0 (1390) being a 0 ++ state decaying ϱϱ and σσ. (σ is the S-wave, I = 0 ππ interaction.) The study of the predictions of this channel proves that the peak height is due to the contribution of two mechanisms having about the same strength: one is Bose-Einstein statistics, the other is the σσ - ϱ 0 ϱ 0 interference. The 3 π − correlations are also reported and discussed.