Summary and conclusions

The $K^{-}_{e3}$ decay has been studied using inflight decays of 25 GeV $K^{-}$, detected by "ISTRA+" magnetic spectrometer. Due to the high statistics, adequate resolution of the detector and good sensetivity over all the Dalitz plot space, the measurement errors are significantly reduced as compared with the previous measurements. The $\lambda_{+}$ parameter of the vector formfactor has been measured to be:

$\lambda_{+}= 0.0306 \pm 0.0018(stat) \pm 0.002(syst)$.

The limits on the possible tensor and scalar couplings have been derived:

$f_{T}/f_{+}(0)=-0.044 ^{+0.068}_{-0.065} ;$

$f_{S}/f_{+}(0)=-0.015 ^{+0.025}_{-0.020}$