Study of the exchange mechanisms in the rho production reactions π±\pi^{\pm} p→ ρ\rho N at 16 GeV/c

Results are presented of a study of the reactions π+p→ϱ+p, π−p→ϱ−p and π−p →ϱ0n, all at 16 GeV/c. For ϱ+ and ϱ−, the dσ/dt′ distributions have a wide forward dip which results from ω exchange. For ϱ0, the dσ/dt′ distribution is consistent with having a narrower forward dip as expected for π-exchange. The ω-exchange contribution is isolated from a linear combination of the three differential cross sections. It is found that the variation of the ω-exchange contribution with the energy s is consistent with s2αω(t)−2, where αω(t) = 0.5 + t. Using the Harari absorption model, the radius of interactions is found to be independent of energy. Evidence that exchange of both spin-parity series occurs was obtained from the density matrix elements. The values of (ϱ11 + ϱ1−1) indicate that natural parity exchanges become more important at t′ increases. The study of (ϱ00GJdσ/dt′) allows us to isolate an exchange having the quantum numbers I=0, G=−1, P(−1)J=−1 which may represent the contribution of a “cut”, as no particle carrying these quantum numbers is known