Mainz 2012 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 16: Hadronenstruktur und -spektroskopie

HK 16.8: Talk

Tuesday, March 20, 2012, 18:30–18:45, RW 2

Photon Fusion Reactions in Chiral Perturbation Theory — •Maximilian Duell and Norbert Kaiser — Physik Department, Technische Universität München, 85747 Garching

Motivated by the proposal of the ALICE-collaboration at CERN to measure cross sections for photon-photon fusion γγ → hadrons in ultraperipheral heavy-ion collisions, the reaction γγ → π⁺π⁻ is revisited in chiral perturbation theory. The NLO corrections to scalar QED are given by the pion electric and magnetic polarizabilities and chiral pion rescattering terms of combined magnitude 10 − 15 percent with respect to LO.

At leading order we extend these calculations to the radiative process γγ→π⁺π⁻γ and compute the corresponding photon spectrum dσ/dω. We study the influence of pion structure effects and compare to the soft photon approximation dσ/dω = σ_soft/ω. We also calculate the total cross section for the 4-body process γγ→π⁺π⁻π⁺π⁻.

Work supported in part by BMBF, GSI and by the DFG Cluster of Excellence: Origin and Structure of the Universe