Additional nucleon current contributions to neutrinoless double beta decay- art. no. 055502

We have examined the importance of momentum-dependent-induced nucleon curre nts such as weak-magnetism and pseudoscalar couplings to the amplitude of n eutrinoless double beta decay (0 nu beta beta decay) in the mechanisms of l ight and heavy Majorana neutrino, as well as in that of Majoron emission. S uch effects are expected to occur in all nuclear models in the direction of reducing the light neutrino matrix elements by about 30%. To test this we have performed a calculation of the nuclear matrix elements of the experime ntally interesting nuclei A=76, 82, 96, 100, 116, 128, 130, 136, and 150 wi thin the proton-neutron renormalized quasiparticle random-phase approximati on. We have found that indeed such corrections vary somewhat from nucleus t o nucleus, but in all cases they are greater than 25%. In the case of a hea vy neutrino the effect is much larger (up to a factor of 6). Combining our results with the best presently available experimental limits on the half-l ife of the 0 nu beta beta decay, we have extracted new limits on the effect ive neutrino mass (light and heavy) and the effective Majoron coupling cons tant. [S0556-2813(99)05610-1].