Neutrino mass, bulk majoron and neutrinoless double beta decay
  A new economical model for neutrino masses is proposed in the context of brane bulk scenarios for particle physics, where global B-L symmetry of the standard model is broken spontaneously by a gauge singlet Higgs field in the bulk. This leads to a bulk majoron whose KK excitations may make it visible if neutrinoless double beta decay if the string scale is close to a TeV. It also leads to neutron-anti-neutron oscillation process with transition times which can be in the range accessible to proposed experiments. 
R. N. Mohapatra, A. Perez-Lorenzana and C. A. de S. Pires