Experiment 865 at the Brookhaven AGS obtained 410 K+ -> e+ nu e+e- and 2679 K+ -> mu+ nu e+e- events including 10% and 19% background. The branching ratios were measured to be (2.48+-0.14(stat.)+-0.14(syst.))x10^-8 (m_ee>150 MeV) and (7.06+-0.16+-0.26)x10^-8 (m_ee>145 MeV), respectively. Results for the decay form factors are presented.
@article{arxiv.hep-ex/0204006,
title = {Experimental Study of the Radiative Decays K+ -> mu+ nu e+e- and K+ -> e+ nu e+e-},
author = {A. A. Poblaguev and R. Appel and G. S. Atoyan and B. Bassalleck and D. R. Bergman and N. Cheung and S. Dhawan and H. Do and J. Egger and S. Eilerts and W. Herold and V. V. Issakov and H. Kaspar and D. E. Kraus and D. M. Lazarus and P. Lichard and J. Lowe and J. Lozano and H. Ma and W. Majid and S. Pislak and P. Rehak and A. Sher and J. A. Thompson and P. Truoel and M. E. Zeller},
journal= {arXiv preprint arXiv:hep-ex/0204006},
year = {2008}
}