Neutrinoless double beta decay experiment

The search for neutrinoless double beta decay ($0\nu \beta \beta$) is one of the key experiments for determining unresolved properties of neutrinos. Experimental observation of $0\nu \beta \beta$ would provide a clear demonstration of the Majorana nature of neutrinos and a lepton number violating process in particle physics. This report is a brief review describing the $0\nu \beta \beta$ process and its significance. The detector technologies used in the present and proposed $0\nu \beta \beta$ experiments are compared among their recent experimental results. Moreover, the sensitivities for $0\nu \beta \beta$ discovery in a number of present and proposed $0\nu \beta \beta$ experiments are introduced.