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arXiv · hep-ph/0506265

Low-energy photon-photon collisions to two loops revisited

Juerg Gasser·Mikhail A. Ivanov·Mikko E. Sainio
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Abstract

In view of ongoing experimental activities to determine the pion polarizabilities, we have started to recalculate the available two-loop expressions in the framework of chiral perturbation theory, because they have never been checked before. We make use of the chiral Lagrangian at order p^6 now available, and of improved techniques to evaluate the two-loop diagrams. Here, we present the result for the neutral pions. The cross section for the reaction gamma+gamma->pi0+pi0 agrees with the earlier calculation within a fraction of a percent. We present analytic results for the dipole and quadrupole polarizabilities, and compare the latter with a recent evaluation from data on gamma+gamma->pi0+pi0.

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Juerg Gasser, Mikhail A. Ivanov, Mikko E. Sainio. 2005-06-25. Low-energy photon-photon collisions to two loops revisited. https://doi.org/10.1016/j.nuclphysb.2005.09.010

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