Has neutrinoless double β decay of 76Ge been really observed?

The claim of discovery of the neutrinoless double beta (0ν2β) decay of 76Ge [Mod. Phys. Lett. A 16 (2001) 2409] is considered critically and firm conclusion about, at least, prematurity of such a claim is derived on the basis of a simple statistical analysis of the measured spectra. This result is also proved by analyzing the cumulative data sets of the Heidelberg–Moscow and IGEX experiments. Besides, it allows us to establish the highest worldwide half-life limit on the 0ν2β decay of 76Ge: T1/20ν⩾2.5 (4.2)×1025 yr at 90% (68%) C.L. This bound corresponds to the most stringent constraint on the Majorana neutrino mass: mν⩽0.3 (0.2) eV at 90% (68%) C.L.