Two-pion production in deuteron-deuteron collisions at low energies

Abstract

Abstract. The cross section for the dd → 4 He ππ reaction is estimated near threshold in a two-step model where a pion created in a first interaction produces a second pion in a subsequent interaction. This approach, which describes well the rates of 2π and η production in the pd → 3 He ππ and dd → 4 He η reactions, leads to predictions that are much too low compared to experiment. Alternatives to this and the double-∆ model will have to be sought to explain these data.

Exclusive measurement of two-pion production in the reaction

“…Not only does this model reproduce quantitatively the missing-mass spectra obtained between 0.8 and 2.4 GeV [13], it also predicts quite well the measured deuteron analyzing powers [14]. On the other hand, both this and other dynamical models [28] fail completely to describe the low energy data [15][16][17].…”