Bounds on the coupling constants of the Majoron to two neutrinos in extra dimensions from Z → νν(J) decay

We give an overview for the bounds of Majoron-neutrino coupling constants from supernova and accelerators. Using the accurate known value for the invisible partial width for Z boson we obtained constraints on the coupling of the Majoron to two neutrinos, for singlet Majoron model, in case of 3+1 dimensions as well as in extra dimensions, where we assumed the singlet Majoron can propagate in higher dimensions. We found that the predicted coupling constants are far below these upper bounds if a natural see-saw is adopted. Also, the expected increase in Z partial width due to many Kaluza-Klein excitations has been suppressed due to the decrease of the coupling constants.