Large breaking of isospin symmetry in an electroweak SU(2)left x U(1) gauge theory of J=0 mesons: the case of K -> Pi Pi decays

K -> Pi Pi decays are investigated in the framework of the SU(2)left x U(1) gauge theory of J=0 mesons proposed in ref.[1], to which is added an interaction between mesons respecting the two symmetries generally attributed to strong interactions, flavour symmetry and parity conservation. It is shown that the damping of the K+ -> Pi+ Pi0 amplitude with respect to the ones of Kshort -> Pi Pi results from a cancelation between the W and Z gauge bosons. The ratio of the two types of amplitudes is sensitive to the spectrum of electroweak (pseudoscalar and scalar) mass eigenstates, an in particular to the mass of the Higgs boson. In the case where scalars and pseudoscalars are degenerate, the amplitudes satisfy the lower bound |(Kshort -> Pi+ Pi-) / (K+ -> Pi+ Pi0)| > 1/tan(Weinberg angle)^2.