We measured the differential production cross section for producing pions in 12.2-GeV/c $p-p$ collisions on lines of fixed $P_1$ and $P_{\perp }$ in the c.m. system. We found that $\frac{d^2\sigma }{d\Omega \mathrm{dp}}$ is maximum at $P_1=0\mathrm{}$, in disagreement with our earlier result, which supported the two-center model. We have evidence that the earlier result is wrong. It also appears that in the c.m. system, $\frac{d^2\sigma }{d\Omega \mathrm{dp}}$ is factorable into functions of $P_1$ and $P_{\perp }$. In the $P_{\perp }$ dependence we found a very sharp forward peak of the form $e^{-15\mathrm{}{P_{\perp }}^2}$.

• Received 18 August 1969

DOI:https://doi.org/10.1103/PhysRevLett.23.1055