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Communication Dans Un Congrès Année : 2009

Dispersive construction of two-loop P->3\pi (P=K,\eta) amplitudes

Résumé

The branching ratio of the \eta->3\pi decay is an important source of information on the value of the quark mass ratio 1/R=(m_d-m_u)/(m_s-\hat m). Furthermore, isospin breaking effects in the decays K->3\pi provide information on the pion scattering lengths. The cusp effect in the K->3\pi decays is presently being analyzed by the NA48 and KTeV experiments. From the theoretical point of view, these processes have been studied by different methods. We propose a unified and relativistic treatment relying on very general principles, unitarity, analyticity and crossing symmetry, combined with chiral counting, in order to construct model-independent representations of the corresponding amplitudes that are valid at two loops. A general description of the procedure is given and is illustrated in the case of the \eta decay amplitude in the leading order in the isospin breaking.

Dates et versions

hal-00390378 , version 1 (02-06-2009)

Identifiants

Citer

M. Zdrahal, K. Kampf, M. Knecht, J. Novotny. Dispersive construction of two-loop P->3\pi (P=K,\eta) amplitudes. International Workshop on Effective Field Theories: from t he pion to the upsilon, Feb 2009, Valence, Spain. pp.063. ⟨hal-00390378⟩
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