On Vud determination from kaon decays

The pion β decay π+→π0e+ν proceeds through pure weak vector hadronic currents and, therefore, the theoretical prediction for it is more reliable than for the processes with axial-vector current contribution. For example, recently the pion β decay has been used for Vud determination. The main aim of this letter is to point that kaon β decay K0→K+(π+π0)e-ν-bar analogously can be used for this purpose