Search for Majoron-emitting modes of double-beta decay of $^{136}$Xe   with EXO-200
  EXO-200 is a single phase liquid xenon detector designed to search for neutrinoless double-beta decay of $^{136}$Xe. Here we report on a search for various Majoron-emitting modes based on 100 kg$\cdot$yr exposure of $^{136}$Xe. A lower limit of $T^{^{136}Xe}_{1/2} >1.2 \cdot 10^{24}$ yr at 90% C.L. on the half-life of the spectral index = 1 Majoron decay was obtained, corresponding to a constraint on the Majoron-neutrino coupling constant of $|< g^{M}_{ee} >|<$ (0.8-1.7)$\cdot$10$^{-5}$. 
EXO-200 Collaboration: J.B. Albert, D.J. Auty, P.S. Barbeau, E.   Beauchamp, D. Beck, V. Belov, C. Benitez-Medina, M. Breide...
hep-ex nucl-ex physics.ins-det