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HK: Physik der Hadronen und Kerne

HK 13: Poster-Sitzung: Theorie

HK 13.11: Poster

Dienstag, 18. März 2003, 13:30–15:30, Foyer

Complete next-to-leading order calculation for pion production in nucleon-nucleon collisions at threshold — •Norbert Kaiser¹ und Christoph Hanhart² — ¹Physik Department T39, Technische Universität München, D-85747 Garching — ²Forschungszentrum Jülich, Institut für Kernphysik (Theorie), D-52425 Jülich

Based on a counting scheme that explicitly takes into account the large momentum √M m_π characteristic for pion production in nucleon-nucleon collisions we calculate all diagrams for the reaction NN → NNπ at threshold up to next-to-leading order. At this order there are no free parameters and the size of the next-to-leading order contributions is in line with the expectation from power counting. The total sum of loop corrections vanishes at that order for the process pp → ppπ⁰ at threshold. The inclusion of explicit delta degrees of freedom leads to vanishing loop contributions at next-to-leading order in both reaction channels pp→ ppπ⁰, pnπ⁺ at threshold.

[1] C. Hanhart and N. Kaiser, Phys. Rev. C66 (2002) in print; nucl-th/0208050