Abstract
Five rare radiative kaon decays, \(K^{+}\to\pi^{0}\mu^{+}\nu_{\mu}\gamma\) , \(K^{+}\to\pi^{0}e^{+}\nu_{e}\gamma\) , \(K^{+}\to\mu^{+}\nu_{\mu}\gamma\) , \(K^{+}\to e^{+}\nu_{e}\gamma\) , \(K^{+}\to\pi^{+}\pi^{0}\pi^{0}\gamma\) are studied by OKA experiment at the RF-separated 17.7 GeV/c momentum kaon beam of the IHEP U-70 proton synchrotron. For the first two decays, branching ratios are obtained and \(T\) -odd correlation is measured. For the \(K^{+}\to\mu^{+}\nu_{\mu}\gamma\) decay vector and axial-vector form factors difference \(F_{V}-F_{A}\) is measured. For the \(K^{+}\to e^{+}\nu_{e}\gamma\) decay branching ratio is measured. For the \(K^{+}\to\pi^{+}\pi^{0}\pi^{0}\gamma\) decay branching ratios is obtained. For \(K^{+}\to\pi^{0}\mu^{+}\nu_{\mu}\gamma\) a discrepancy of 4.6 \(\sigma\) above calcullations without structure radiation is observed. For Br ( \(K^{+}\to\pi^{0}e^{+}\nu_{e}\gamma\) ) a discrepancy of > 5 \(\sigma\) for the same case is observed. For \(F_{V}-F_{A}\) ( \(K^{+}\to\mu^{+}\nu_{\mu}\gamma\) decay) a discrepancy of 2.9 \(\sigma\) above \(\chi\) PT is observed. Our results are considered as preliminary.
