Analytical dispersive construction of eta -> 3 pi amplitude: First order in isospin breaking

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Because of their small electromagnetic corrections, the isospin-breaking decays n -> 3 pi seem to be good candidates for extracting isospin-breaking parameters similar to(m(d) - m(u)). This task is unfortunately complicated by large chiral corrections and the discrepancy between the experimentally measured values of the Dalitz parameters describing the energy dependence of the amplitudes of these decays and those predicted from chiral perturbation theory. We present two methods based on an analytic dispersive representation that use the information from the NNLO chiral result and the one from the measurement of the charged n -> 3 pi decay by KLOE together in a harmonized way in order to determine the value of the quark mass ratio R. Our final result is R = 37.7 +/- 2.2. This value supplemented by values of m(s)/(m) over cap or even (m) over cap and m(s) from other methods (as sum-rules or lattice) enables us to obtain further quark mass characteristics. For instance the recent lattice value for m(s)/(m) over cap similar to 27: 5 leads to Q = 23.1 +/- 0.7. We also quote the corresponding values of the current masses m(u) and m(d).


  • Karol Kampf
  • Marc Knecht
  • Jiri Novotny
  • Martin Zdrahal
Enheter & grupper

Ämnesklassifikation (UKÄ) – OBLIGATORISK

  • Subatomär fysik
TidskriftPhysical Review D (Particles, Fields, Gravitation and Cosmology)
StatusPublished - 2011
Peer review utfördJa