Dresden 2013 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 44: Hadronenstruktur und -spektroskopie

HK 44.6: Talk

Tuesday, March 5, 2013, 18:15–18:30, HSZ-403

Photon-fusion reactions from the chiral Lagrangian with dynamical light vector mesons — •Igor Danilkin¹, Matthias Lutz¹, Stefan Leupold², and Carla Terschlüsen² — ¹GSI, Planckstrßae 1, 64291 Darmstadt, Germany — ²Uppsala Universitet, Box 516, 75120 Uppsala, Sweden

We study the reactions γγ→ π⁰π⁰, π⁺π⁻, K⁰K⁰, K⁺K⁻, η η and π⁰η based on a chiral Lagrangian with dynamical light vector mesons as formulated within the hadrogenesis conjecture. At present our chiral Lagrangian contains 5 unknown parameters that are relevant for the photon fusion reactions. They parameterize the strength of interaction terms involving two vector meson fields. These parameters are fitted to photon fusion data γγ→ π⁰π⁰, π⁺π⁻, π⁰η and to the decay η→π⁰γγ. In order to derive gauge invariant reaction amplitudes in the resonance region constraints from micro-causality and exact coupled-channel unitarity are used. Our results are in good agreement with the existing experimental data from threshold up to about 0.9 GeV for the two-pion final states. The a₀ meson in the π⁰η channel is dynamically generated and an accurate reproduction of the γγ→ π⁰η data is achieved up to 1.2 GeV. Based on our parameter sets we predict the γγ→ K⁰K⁰, K⁺K⁻, η η cross sections [1].

[1] I. V. Danilkin, M. F. M. Lutz, S. Leupold and C. Terschlusen, arXiv:1211.1503 [hep-ph].