K⁺ → π⁰µ⁺νγ and K⁺ → π⁰e⁺νγ Decays: Recent Results from the “OKA” Experiment

The K⁺ → π⁰µ⁺νγ(K_µ3γ) and K⁺ → π⁰e⁺νγ (K_e3γ) decays are measured with OKA detector at the RF-separated 17.7 GeV/c momentum kaon beam from the U-70 synchrotron. The data obtained corresponds to the value of 2.62 × 10¹⁰ “live” kaons passing to the decay volume. The ratios of Br(K_µ3γ)/Br(K_µ3) and Br(K_e3γ)/Br(K_e3) are measured. The T-odd correlation ξ_πμγ (ξ_πeγ), which is the mixed product of the momenta of µ⁺(e⁺), π⁰, and γ in the kaon rest frame, is measured. The asymmetry of the distribution in ξ is characterized by the ratio A_ξ = (N₊ − N₋)/(N₊ + N₋), where N₊₍₋₎ is the number of events with positive (negative) ξ. The values of A_ξ for K_µ3γ and for K_e3γ is obtained.