Bochum 1998 – scientific programme

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HK: Hadronen und Kerne

HK 27: Hadronic Probes III, Particle Production

HK 27.2: Group Report

Tuesday, March 17, 1998, 14:30–15:00, C

Pion production in proton–proton collisions — •C. Hanhart, J. Haidenbauer, Ulf-G. Meißner, and J. Speth — Institut f"ur Kernphysik des Forschungszentrum J"ulich GmbH, 52425 J"ulich

Based on well established models for nucleon–nucleon and pion–nucleon scattering we present a model for pion production in proton proton collisions [1]. The Δ (1232) degree of freedom is explicitly taken into account. All possible final states (pp → ppπ⁰, pp → dπ⁺ and pp → pnπ ⁺) are investigated. We obtain an overall satisfactory agreement with available data on total cross sections as well as polarization observables from pion production threshold up to the Delta resonance region. We discuss the effect of the Delta isobar and the sensitivity to off–shell properties of the πN amplitude. The need for using a microscopic model to treat the πN subsystem is pointed out. The results are compared to those obtained in tree level chiral perturbation theory [2,3]. Possible sources of the differences are discussed.

[1] C. Hanhart, J. Haidenbauer, A. Reuber, C. Schütz and J. Speth, Phys. Lett. B 358, 21 (1995)

[2] T. Sato, T.–S. H. Lee, F. Myhrer and K. Kubodera, Phys. Rev. C 56, 1246 (1997)

[3] C. Hanhart, J. Haidenbauer, M. Hoffmann, Ulf-G. Meißner and J. Speth, submitted for publication