Study of the K- -> mu- nu pi0 decay

The decay $K^{-}\to {\mu }^{-}\bar{\nu }{\pi }^0$ has been studied using in-flight decays detected with ``ISTRA+‘’ setup operating in the 25 GeV negative secondary beam of the U-70 PS. About 112K events were used for the analysis. The ${\lambda }_{+}$ and ${\lambda }_0$ slope parameters of the decay formfactors $f_{+}(t)$, $f_0(t)$ have been measured : ${\lambda }_{+}=0.0321\pm 0.004$(stat) $\pm 0.002$(syst) ${\lambda }_0=0.0209\pm 0.004$(stat) $\pm 0.002$(syst); the correlation $d \lambda_{0}/d \lambda_{+}=-0.46$ The limits on the possible tensor and scalar couplings have been derived: $f_T\mathrm{/}{f}_{+}(0)=-0.021\pm 0.028$(stat) $\pm 0.014$(theory); $f_S\mathrm{/}{f}_{+}(0)=0.004\pm 0.005$(stat) $\pm 0.005$(theory)