LAB observables for the muon polarization in K^+ --> π^+ μ^+ μ^-

D. Gomez Dumm, J. Vidal

We analyse the muon longitudinal polarization asymmetry Δ_long in the decay K^+ --> π^+ μ^+ mu^-. It is stressed that, since the muon helicities are not Lorentz-invariant quantitie…