Study of the K− → e−νπ0 decay

The decay K− → e−νπ0 has been studied using in-flight decays detected with the ISTRA+ setup working at the 25-GeV negative secondary beam of the U-70 PS. About 130K events were used for the analysis. The λ+ parameter of the vector form factor has been measured: λ+=0.0293±0.0015(stat.)±0.002(syst.). The limits on the possible tensor and scalar couplings have been derived: fT/f+(0)=−0.045±0.060(stat.) and fS/f+(0)=−0.019 −0.016 +0.025 (stat.).