Photon-fusion reactions from the chiral Lagrangian with dynamical light vector mesons

• Published in: The European physical journal. C, Particles and fields Particles and fields, 2013-04, Vol.73 (4), p.1-16, Article 2358
• Main Authors: Danilkin, I. V., Lutz, M. F. M., Leupold, S., Terschlüsen, C.
• Format: Article
• Language: English
• Subjects: Astronomy; Astrophysics and Cosmology; Channels; Chiral Lagrangians; Cross sections; Dispersion relations; Elementary Particles; Hadrons; Heavy Ions; Invariants; Joining; Mathematical analysis; Measurement Science and Instrumentation; Meson production; Nuclear Energy; Nuclear Physics; Partial-wave analysis; Physics; Physics and Astronomy; Quantum Field Theories; Quantum Field Theory; Regular Article - Theoretical Physics; Reproduction; String Theory; Vector mesons; Vector-meson dominance
• ISSN: 1434-6044; 1434-6052; 1434-6052
• DOI: 10.1140/epjc/s10052-013-2358-1

We study the reactions γγ → π 0 π 0 , π + π − , , K + K − , ηη and π 0 η based on a chiral Lagrangian with dynamical light vector mesons as formulated within the hadrogenesis conjecture. At present our chiral Lagrangian contains five 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 → π 0 π 0 , π + π − , π 0 η and to the decay η → π 0 γγ . In order to derive gauge invariant reaction amplitudes in the resonance region constraints from maximal analyticity 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 a 0 meson in the π 0 η channel is dynamically generated and an accurate reproduction of the γγ → π 0 η data is achieved up to 1.2 GeV. Based on our parameter sets we predict the γγ → , K + K − , ηη cross sections.