Critical look at fKfπ in the (3,Â 3̄)+(3̄,Â 3) model
We discuss the prediction of fKfπ that follows from chiral symmetry in the (3,Â 3̄)+(3̄,Â 3) model from a general point of view. We present the results of the one-loop corrections in the renormalizable SU3 σ model. These results are compared with a number of other approaches, including chiral perturbation theory. All approaches discussed here have uncertainties in fKfπ at least as large as, often much larger than, the experimental error in fKfπ. This is traced to the appearance of the mass difference mη2-mK2 which is uncertain to ±4% owing to isospin splitting. © 1976 The American Physical Society.