https://doi.org/10.1140/epja/i2011-11015-6
Letter
Isospin breaking in pion Compton scattering
Physik-Department, Technische Universität München, D-85747, Garching, Germany
* e-mail: nkaiser@ph.tum.de
Received:
28
October
2010
Accepted:
5
January
2011
Published online:
1
February
2011
Using chiral perturbation theory we calculate for pion Compton scattering the isospin-breaking effects induced by the difference between the charged and neutral pion mass. At one-loop order this correction is directly proportional to 
and free of (electromagnetic) counterterm contributions. The differential cross-section for charged pion Compton scattering 
gets affected (in backward directions) at the level of a few permille. At the same time the isospin-breaking correction leads to a small shift of the pion polarizabilities by 
fm^3. In case of the low-energy 
reaction isospin breaking manifests itself through a cusp effect at the 
threshold. We give an improved estimate for it based on the empirical 
-scattering length difference 
.
© SIF, Springer-Verlag Berlin Heidelberg, 2011
