出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：The branching ratio of the h →3p decay is an important source of information on the value of the
quark mass ratio 1R
= md−mu
ms−bm . Furthermore, isospin breaking effects in the decays K→3p provide
information on the pion scattering lengths. The cusp effect in the K → 3p 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 h decay amplitude in the leading order in the isospin breaking.
