1110.1610 (ISTRA+ collaboration: V. A. Duk et al.)

Search for Heavy Neutrino in K->mu nu_h(nu_h-> nu gamma) Decay at ISTRA+
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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, S. A. Kholodenko, V. M. Leontiev, V. F. Obraztsov, V. A. Polyakov, V. I. Romanovsky, O. V. Stenyakin, O. G. Tchikilev, V. A. Uvarov, O. P. Yushchenko

Heavy neutrino nu_h with m_h < 300MeV/c^2 can be effectively searched for in kaon decays. We put upper limits on mixing matrix element |U_mu_h}|^2 for radiatively decaying nu_h from K->mu nu_h (nu_h -> nu gamma) decay chain in the following parameter region: 30MeV/c^2 < m_h < 80MeV/c^2; 10^{-11}sec < tau_h < 10^{-9}sec. For the whole region |U_{mu h}|^2 < 5 x 10^{-5} for Majorana type of nu_h and | U_{\mu h}|^2 < 8 x 10^{-5} for the Dirac case.

View original: http://arxiv.org/abs/1110.1610