Final results of the Aurora experiment to study $2\beta$ decay of $^{116}\mathrm{Cd}$ with enriched $^{116}\mathrm{Cd}{\mathrm{WO}}_{4}$ crystal scintillators

The double-beta decay of 116Cd has been investigated with the help of radiopure enriched 116CdWO4 crystal scintillators (mass of 1.162 kg) at the Gran Sasso underground laboratory. The half-life of 116Cd relative to the 2ν2βdecay to the ground state of 116Sn was measured with the highest up-to-date accuracy as T1/2≥2.63(+0.11−0.12) ×10^19 yr. A new improved limit on the 0ν2βdecay of 116Cd to the ground state of 116Sn was set as T1/2≥2.2×10^23yr at 90% C.L., which is the most stringent known restriction for this isotope.It corresponds to the effective Majorana neutrino mass limit in the rangeh m-v≤(1.0–1.7) eV, depending on the nuclear matrix elements used in the estimations. New improved half-life limits for the 0ν2β decay with majoron(s) emission, Lorentz-violating 2ν2β decay, and 2β transitions to excited states of 116Sn were set at the level of T1/2≥10^20–10^22 yr. New limits for the hypothetical lepton-number violating parameters(right-handed currents admixtures in weak interaction, the effective majoron-neutrino coupling constants,R-parity violating parameter, Lorentz-violating parameter, heavy neutrino mass) were set.