A sum rule approach to the violation of Dashen's theorem
Abstract
A classic sum rule by Das et al. is extended to seven of the lowenergy constants K_{1}, introduced by Urech, which parametrize electromagnetic corrections at chiral order O( e^{2}p^{2}). Using the spurion formalism, a simple convolution representation is shown to hold and the structure in terms of the chiral renormalization scale, the QCD renormalization scale and the QED gauge parameter is displayed. The role of the resonances is studied as providing rational interpolants to relevant QCD npoint functions in the Euclidean domain. A variety of asymptotic constraints must be implemented which have phenomenological consequences. A current assumption concerning the dominance of the lowestlying resonances is shown clearly to fail in some cases.
 Publication:

Nuclear Physics B
 Pub Date:
 February 1997
 DOI:
 10.1016/S05503213(97)004641
 arXiv:
 arXiv:hepph/9701400
 Bibcode:
 1997NuPhB.504..381M
 Keywords:

 High Energy Physics  Phenomenology
 EPrint:
 A few corrections and improvements made, the list of references is more complete