Data from a high-resolution experiment on the reaction ${\pi }^{+}p\to {\pi }^{+}+p$ at 5 GeV/c show a very deep, sharp dip in $\frac{d\sigma }{\mathrm{dt}}$ at $t=-2.8\mathrm{}$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$ and a gentle exponential decrease in $\frac{d\sigma }{\mathrm{du}}$ between $u=-1.5\mathrm{} \mathrm{and} -3.5\mathrm{}$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$.

• Received 25 March 1970

DOI:https://doi.org/10.1103/PhysRevLett.24.1361