An experimental investigation of the radiative structure decay K + → e +υγ

• Published in: Nuclear physics. B 1979-03, Vol.149 (3), p.365-380
• Main Authors: Heintze, J., Heinzelmann, G., Igo-Kemenes, P., Mundhenke, R., Rieseberg, H., Schürlein, B., Siebert, H.W., Soergel, V., Stelzer, H., Streit, K.-P., Walenta, A.H.
• Format: Article
• Language: English
• ISSN: 0550-3213; 1873-1562
• DOI: 10.1016/0550-3213(79)90001-4

The decay K + → e + υγ has been investigated. For the structure-dependent part with positive γ-helicity (SD +) the branching ratio Γ( SD +) Γ( K μ2 ) = (2.33 ± 0.42) × 10 −5 is obtained from 51 ± 3 events observed in the kinematical region E e ⩾ 235 MeV, E γ > 48 MeV and θ e γ > 140°. For the corresponding part with negative γ-helicity we obtain an upper limit Γ(SD −)/ Γ(SD +) < 11 (90% CL) from the sample of electrons with energies 220 MeV ⩽ E e < 230 MeV and with no γ in the backward direction. This upper limit implies that the ratio of structure-dependent axial vector amplitudes lies outside the region −1.8 < a K υ K < −0.54 . For the decay K + → e +νν ν the limit Γ( K + → e +νν ν)/Γ( K e2 ) < 3.8 90% confidence level) was found.