2022 Impact factor 4.4
Particles and Fields
Eur. Phys. J. C 6, 297-306
DOI 10.1007/s1005298000912

Two-loop integrals in chiral perturbation theory

J. Gasser1 - M.E. Sainio2

1 Institute of Theoretical Physics, University of Berne, Sidlerstrasse 5, CH-3012 Berne, Switzerland
2 Department of Physics, University of Helsinki, P.O. Box 9, FIN-00014 Helsinki, Finland

Received: 14 April 1998 / Published online: 7 August 1998

We consider chiral perturbation theory in the meson sector at order E6. In the terminology of the external field technique, the genuine two-loop diagrams so generated are of the sunset type. We discuss the evaluation of several of these in the case where the masses of the particles running in the loops are equal. In particular, we present integral representations that are suitable for the evaluation of diagrams in kinematical regions where branch points and cuts are present.

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