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Inclusive study of off-mass-shell π ± p and π ± π</mml:…

1981; American Physical Society; Volume: 24; Issue: 5 Linguagem: Inglês

10.1103/physrevd.24.1117

1538-4500

F. Barreiro, O. Benary, E. Hafen, R. I. Hulsizer, V. Kistiakowsky, J. Barry McManus, A. Napier, I. A. Pless, J. P. Silverman, P. C. Trepagnier, J. Wolfson, R. K. Yamamoto,

Particle physics theoretical and experimental studies

We have studied inclusive ${\ensuremath{\rho}}^{0}$ and ${\ensuremath{\Delta}}^{++}$ production in ${\ensuremath{\pi}}^{+}p$ and ${\ensuremath{\pi}}^{\ensuremath{-}}p$ interactions at 15 GeV/c in a region where pion exchange has been found to dominate the resonance production. By using ${\ensuremath{\rho}}^{0}$ production, the off-mass-shell interactions of virtual pions with the target protons have been studied and compared with the same on-shell reactions at comparable energy. No significant differences between on-shell and off-shell reactions have been found in topological-cross-section ratios, inclusive longitudinal- or transverse-momentum distributions, or elastic $\frac{d\ensuremath{\sigma}}{\mathrm{dt}}$ distributions. The effect of the negative mass squared of the virtual pions has also been studied. Inclusive ${\ensuremath{\Delta}}^{++}$ production has been found to be dominated by pion exchange for $|t|\ensuremath{\lesssim}0.4$ (${\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^{2}$. We have studied the interactions of these off-shell pions with the beam pions as a function of energy. The ratio $\frac{{\ensuremath{\sigma}}_{\mathrm{el}}}{{\ensuremath{\sigma}}_{T}}$ and the average charged-particle multiplicities $〈{n}_{X}〉$ have been examined and compared with those for various hadron-proton reactions. The values of $〈{n}_{X}〉$ have also been studied in terms of a simple model and found to give results consistent with studies at higher energies. We also present longitudinal- and transverse-momentum distributions for produced pions, as well as $\frac{d\ensuremath{\sigma}}{\mathrm{dt}}$ distributions for $\ensuremath{\pi}\ensuremath{\pi}$ elastic scattering.