Study of K − → π 0 e − ν e γ decay with ISTRA + setup

Results of the study of the K− → π0e−νγ decay at ISTRA+ setup are presented. 4476 events of this decay have been observed. The ratio of branching ratios (R), R = Br(K −→π0e−νeγ) Br(K−→π0e−νe) = (1.81± 0.03(stat.)± 0.07(syst.))× 10−2, has been obtained for E∗ γ > 10 MeV and θ ∗ eγ > 10◦. For comparison with previous experiments, the branching ratio with cuts E∗ γ > 10 MeV, 0.6 < cosθ ∗ eγ < 0.9 is calculated, R = Br(K−→π0e−νeγ) Br(K−→π0e−νe) = (0.47 ± 0.02(stat.) ± 0.03(syst.)) × 10 −2. For the cuts E∗(γ) > 30 MeV and θ ∗ eγ > 20◦, used in most theoretical papers, we have obtained Br(K− → π0e−νeγ) = (3.13 ± 0.09 ± 0.14) × 10−4. For the asymmetry Aξ we get Aξ = −0.015±0.021. At present it is the best estimate of this asymmetry.