%0 Journal Article
%T Limits on Majoron-emitting double-beta decays of Xe-136 in the KamLAND-Zen experiment
%A KamLAND-Zen Collaboration
%A :
%A A. Gando
%A Y. Gando
%A H. Hanakago
%A H. Ikeda
%A K. Inoue
%A R. Kato
%A M. Koga
%A S. Matsuda
%A T. Mitsui
%A T. Nakada
%A K. Nakamura
%A A. Obata
%A A. Oki
%A Y. Ono
%A I. Shimizu
%A J. Shirai
%A A. Suzuki
%A Y. Takemoto
%A K. Tamae
%A K. Ueshima
%A H. Watanabe
%A B. D. Xu
%A S. Yamada
%A H. Yoshida
%A A. Kozlov
%A S. Yoshida
%A T. I. Banks
%A J. A. Detwiler
%A S. J. Freedman
%A B. K. Fujikawa
%A K. Han
%A T. O'Donnell
%A B. E. Berger
%A Y. Efremenko
%A H. J. Karwowski
%A D. M. Markoff
%A W. Tornow
%A S. Enomoto
%A M. P. Decowski
%J Physics
%D 2012
%I arXiv
%R 10.1103/PhysRevC.86.021601
%X We present limits on Majoron-emitting neutrinoless double-beta decay modes based on an exposure of 112.3 days with 125 kg of Xe-136. In particular, a lower limit on the ordinary (spectral index n = 1) Majoron-emitting decay half-life of Xe-136 is obtained as T_{1/2}^{0\nu\chi^{0}} > 2.6 x 10^{24} yr at 90% C.L., a factor of five more stringent than previous limits. The corresponding upper limit on the effective Majoron-neutrino coupling, using a range of available nuclear matrix calculations, is <g_{ee}> < (0.8 - 1.6) x 10^{-5}. This excludes a previously unconstrained region of parameter space and strongly limits the possible contribution of ordinary Majoron emission modes to 0\nu\beta\beta decay for neutrino masses in the inverted hierarchy scheme.
%U http://arxiv.org/abs/1205.6372v2