Study of the Reactionπ−p→ρ0nat 15GeVc

We present the results of a wire spark-chamber experiment studying the reaction ${\pi }^{-}p\to {\pi }^{+}{\pi }^{-}n$ at 15 GeV/c. The differential cross section, $\pi -\pi$ mass distribution, and density-matrix elements have been determined from 10 000 $\pi \pi n$ events ($M_{\pi \pi }<1.0\mathrm{}$ GeV) produced with $-t<\mathrm{}0.30\mathrm{}$ ${\mathrm{}(\mathrm{G}\mathrm{e}\mathrm{V}/\mathrm{c})\mathrm{}}^2$. Both the density-matrix elements and the differential cross section exhibit structure in the forward direction ($-t<\mathrm{}{m_{\pi }}^2$).