Watson's theorem and electromagnetism in Κ → ππ decay

S. Gardner, Ulf G. Meißner, G. Valencia

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


We consider what constraints unitarity and CPT invariance yield on the strong and electromagnetic phases entering Κ → ππ decay. In particular, we show that the relative size of the electromagnetically-induced changes in the I = 0 and I = 2 phase shifts in the two-pion final state do not depend on the explicit coupling to the π+π-γ channel. This demonstrates that Watson's theorem can be extended to include the presence of electromagnetism. We point out the consequences for the general structure of the Κ → ππ decay amplitudes in the presence of isospin violation.

Original languageEnglish
Pages (from-to)44-50
Number of pages7
JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Issue number1-2
StatePublished - May 24 2001

Bibliographical note

Funding Information:
S.G. and U.-G.M. thank the Institute of Nuclear Theory at the University of Washington for its hospitality during the completion of this work. The work of S.G. and G.V. is supported in part by the U.S. Department of Energy under contract numbers DE-FG02-96ER40989 and DE-FG02-01ER41155, respectively.

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


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