Pion-induced pion production on the deuteron

Pion-induced pion production on the deuteron was studied via the reactions ${\pi }^{+}$d→${\pi }^{\mathrm{-}}$ ${\pi }^{+}$pp and ${\pi }^{\mathrm{-}}$d→${\pi }^{+}$ ${\pi }^{\mathrm{-}}$nn. The doubly differential cross sections for these reactions were measured, covering the center-of-mass phase space at incident pion energies of 256, 331, and 450 MeV. Calculations of the quasifree production process on one nucleon were performed in a plane-wave approximation using a phenomenological, on-shell ${\pi }^{\mathrm{-}}$p→${\pi }^{+}$ ${\pi }^{\mathrm{-}}$n amplitude. Comparison of the data with the calculations indicates that the quasifree mechanism dominates these production reactions on the deuteron. Upper limits for bound ${\pi }^{\mathrm{-}}$nn and ${\pi }^{+}$pp systems with small binding energies were also measured. The possible existence of a resonance in these systems near the production threshold was investigated.