Evidence for the Reactionπ−+p→p¯+dand Some Methods of Investigating Virtual Nucleon Exchange Processes

The cross section for the process ${\pi }^{-}+p\to \overline{p}+d$ has been studied in a spark chamber experiment and was found to be 16±10 μb at 4.13 GeV/c and $8_{-8\mathrm{}}^{+12\mathrm{}}$ μb at 4.95 GeV/c. The interpretation of this process in terms of a virtual nuclear exchange is discussed and comparison is made with other possible nucleon exchange reactions such as $p+p\to {\pi }^{+}+d$ and backward pion-nucleon elastic scattering. There is a difficulty in applying Regge theory to these reactions because unequal masses are involved.