Comprehensive Review of Double-Beta Decay Half-Lives*

The double-beta decay is the rarest nuclear physics process, and its experimental half-lives (T$_{1/2}$) exceed the age of the Universe from nine to fourteen orders of magnitude.  Double-beta decay was observed, and its half-life was measured in 14 parent nuclei using direct and geochemical methods.  The decay observables are analyzed using the Evaluated Nuclear Structure Data File (ENSDF) procedures,  and the recommended T$_{1/2}$ were deduced.

Using the calculated values of phase factors,  the effective nuclear matrix elements were extracted and compared with available data. Many thousands of theoretical and experimental works are dedicated to these topics in the last 85 years, and we present two data sets of recommended values to encapsulate the results.