1005.3517 (The ISTRA+ Collaboration: V. A. Duk et al.)

Extraction of Kaon Formfactors from K^- -> mu^- nu_mu gamma Decay at
ISTRA+ Setup    [PDF]

The ISTRA+ Collaboration: V. A. Duk, V. N. Bolotov, A. A. Khudyakov, V. A. Lebedev, A. I. Makarov, V. P. Novikov, A. Yu. Polyarush, S. A. Akimenko, G. I. Britvich, A. P. Filin, A. V. Inyakin, I. Ya. Korolkov, V. M. Leontiev, V. F. Obraztsov, V. A. Polyakov, V. I. Romanovsky, O. G. Tchikilev, V. A. Uvarov, O. P. Yushchenko

The radiative decay K->mu nu gamma has been studied at ISTRA+ setup in a new kinematical region. About 22K events of K^- -> mu^- nu_mu gamma have been observed. The sign and value of Fv-Fa have been measured for the first time. The result is Fv-Fa=0.21(4)(4).

View original: http://arxiv.org/abs/1005.3517