Measurement of the 2νββ decay half-life and search for the 0νββ decay of Cd116 with the NEMO-3 detector

The NEMO-3 experiment measured the half-life of the 2 nu beta beta decay and searched for the 0 nu beta beta decay of Cd-116. Using 410 g of Cd-116 installed in the detector with an exposure of 5.26 y, (4968 +/- 74) events corresponding to the 2 nu beta beta decay of Cd-116 to the ground state of Sn-116 have been observed with a signal to background ratio of about 12. The half-life of the 2 nu beta beta decay has been measured to be T-1/2(2 nu) = [2.74 +/- 0.04(stat) +/- 0.18(syst)] x 10(19) y. No events have been observed above the expected background while searching for 0 nu beta beta decay. The corresponding limit on the half-life is determined to be T-1/2(0 nu) >= 1.0 x 10(23) y at the 90% C. L. which corresponds to an upper limit on the effective Majorana neutrino mass of < m(nu)> <= 1.4-2.5 eV depending on the nuclear matrix elements considered. Limits on other mechanisms generating 0 nu beta beta decay such as the exchange of R-parity violating supersymmetric particles, right-handed currents and majoron emission are also obtained.