Mechanisms of the isospin-breaking decayf1(1285)→f0(980)π0→π+π−π0

Isospin Symmetry Breaking

Isospin symmetry breaking

We discuss the separation of isospin-symmetric and isospin-breaking contributions in the hadronic observables within the framework of QCD plus QED. Further, we briefly review some recent work on the low-energy hadron phenomenology, in which the isospin-breaking effect plays a prominent role.

Isospin breaking in Kl4 decays

Data on Ke4 decays allow one to extract experimental information on the elastic ππ scattering amplitude near threshold, and to confront the outcome of the analysis with predictions made in the framework of QCD. These predictions concern an isospin symmetric world, while experiments are carried out in the real world, where isospin breaking effects – generated by electromagnetic interactions and ...

Isospin breaking and the chiral condensate

With two degenerate quarks, the chiral condensate exhibits a jump as the quark masses pass through zero. I discuss how this single transition splits into two Ising like transitions when the quarks are made non-degenerate. The order parameter is the expectation of the neutral pion field. The transitions represent long distance coherent phenomena occuring without the Dirac operator having vanishi...

Isospin Breaking in K → 3 π Decays I : Strong Isospin Breaking

The CP conserving amplitudes for the decays K → 3π are calculated in Chiral Perturbation Theory. The calculation is made at the next-to-leading order including strong and local electromagnetic isospin breaking. A comparison is made between the squared amplitudes with and without isospin violation to estimate the size of the effect. We find corrections of order five percent in the amplitudes.