High statistics study of the K−→π0μ−ν decay

The decay K−→π0μ−ν has been studied using in-flight decays detected with the “STRA+” spectrometer. About 540K events were collected for the analysis. The λ+ and λ0 slope parameters of the decay form-factors f+(t), f0(t) have been measured: λ+=0.0277±0.0013(stat)±0.0009(syst), λ0=0.0183±0.0011(stat)±0.0006(syst), and dλ0/dλ+=−0.348. The limits on the possible tensor and scalar couplings have been derived: fT/f+(0)=−0.0007±0.0071, fS/f+(0)=0.0017±0.0014. No visible non-linearity in the form-factors have been observed.