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arXiv · hep-ph/9908509

A Quark Model Calculation of gamma gamma to pi pi Including Final State Interactions

H. G. Blundell·S. Godfrey·G. Hay·E. S. Swanson
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Abstract

A quark model calculation of the processes gamma gamma -> pi+ pi- and gamma gamma -> pi0 pi0 is performed. At tree level, only charged pions couple to the initial state photons and neutral pions are not expected in the final state. However, a small but significant gamma gamma -> pi0 pi0 cross section is observed. We demonstrate that this may be accounted for by a rotation in isospin space induced by final state interactions. The resulting pi+ pi- cross section is in good agreement with experiment while the pi0 pi0 cross section is in qualitative agreement with the data.

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H. G. Blundell, S. Godfrey, G. Hay, E. S. Swanson. 1999-12-08. A Quark Model Calculation of gamma gamma to pi pi Including Final State Interactions. https://doi.org/10.1103/physrevc.61.025203

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