Coherent Production of Pions in Deuterium at 5.4GeVc

The reaction ${\pi }^{+}d\to d{\pi }^{+}{\pi }^{+}{\pi }^{-}$ has been investigated at an incident pion beam momentum of 5.4 $\frac{\mathrm{GeV}}{c}$. The three-pion system is observed to be coherently produced off the deuteron target. The reaction is dominated by the quasi-three-body final state $d{\rho }^0{\pi }^{+}$. $D^{*}$ enhancements are observed, but they appear to be the result of kinematic reflections from the $d{\rho }^0{\pi }^{+}$ system. The striking feature of this reaction is the presence of a broad, structureless, low-mass three-pion enhancement in the region between 0.9 and 1.5 GeV.