0(+)-> 2(+) 0 nu beta beta decay triggered directly by the Majorana neutrino mass

We treat 0(+)-->2(+) 0 nu beta beta decays taking into account recoil corre ctions to the nuclear currents. The decay probability can be written as a q uadratic form of the effective coupling constants of the right-handed lepto nic currents and the effective neutrino mass. We calculate the nuclear matr ix elements for the 0(+)-->2(+) 0 nu beta beta decays of Ge-76 and Mo-100, and demonstrate that the relative sensitivities of 0(+)-->2(+) decays to th e neutrino mass and the right-handed currents are comparable to those of 0( +)-->0(+) decays. (C) 2000 Published by Elsevier Science B.V. All rights re served.