Tübingen 2003 – wissenschaftliches Programm

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HK: Physik der Hadronen und Kerne

HK 11: Poster-Sitzung: Elektromagnetische und hadronische Proben

HK 11.17: Poster

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

On the σ-meson production in proton-proton collisions at CELSIUS and COSY energies — •M.M. Kaskulov and P. Grabmayr — Physikalisches Institut, Universität Tübingen

The scalar mesons with vacuum quantum numbers are known to be crucial for the complete understanding of the symmetry breaking mechanisms in QCD, and presumably also for the confinement and the attractive part of the NN interaction. The recent CELSIUS and COSY experiments studying two-pion production in proton-proton collisions, pp→π⁺π⁻pp, can open new hints for the understanding of light-meson spectroscopy and especially of the controversial scalar mesons. In this work we propose a simple model, where the σ-meson production is considered as the main dynamical mechanism for the strong ππ correlations in the final π⁺π⁻pp system. In particular, it is shown that adding an intermediate S-wave structure (σ-meson) in a π⁺π⁻ system with floating mass and width allows for an excellent fit to the data, provided the common mass of this scalar object is m_σ ≃ 400 MeV. It is intriguing, that the proposed single-parameter fit does not require an explicit introduction of the Roper N^*(1440) resonance.