Has a coupling of right-handed quarks to W been observed?

International audienceStringent tests of non-standard electroweak (EW) couplings of (light) quarks are rare because it is not easy to disentangle QCD and EW quantities. We will discuss here a recently proposed test of right-handed charged quark currents, based on Kl3 decay data and the prediction of the Callan-Treiman low energy theorem. Non-standard couplings of fermions to W and Z are suggested by the minimal low-energy effective electroweak theory (LEET) to be the dominant new physics effects. It is shown that coherent values for these couplings emerge from an analysis of Z-pole observables, too, curing in particular the long-standing AbFB puzzle