Observation of the Reactionπ−p→p¯dfrom 4 to 6 GeV/c

Differential cross sections have been measured for the reaction ${\pi }^{-}p\to \overline{p}d$. At 4 GeV/c the total cross section is 0.58 ± 0.08 μb with an angular distribution consistent with isotropy. At 5 GeV/c a pronounced forward dip occurs. In contradiction to simple baryon-exchange models, the cross section is found to be an order of magnitude smaller than that for the line-reversed reaction $\mathrm{pp}\to {\pi }^{+}d$. Upper limits for ${\pi }^{-}d\to \overline{p}t$ were also found.