A complete study of the form factors in K μ3 + decay

Abstract The validity of the V-A theory in Kμ3+ decay is checked and the contribution of the tensor interaction is found to be compatible with zero. A consistent interpretation of measurements of the Kμ3+ Dalit plot density, of the muon polarization in Kμ3+ decay, and of the K μ3 + K e 3 + branching ratio is found to be possible. From a study of the relative magnitude and four-momentum transfer dependence of the vector form factors, the best fit to the combined data is λ+ = 0.060−0.017+0.01, Λ = −0.01−0.11+0.13, and ξ(5mπ2) = −0.93 ± 0.23. The results are compared to current theoretical predictions.