Double-beta decay of \(^{130}\hbox {Te}\) to the first \(0^+\) excited state of \(^{130}\hbox {Xe}\) with CUORE-0

We report on a search for double beta decay of \(^{130}\hbox {Te}\) to the first \(0^{+}\) excited state of \(^{130}\hbox {Xe}\) using a \(9.8\,\hbox {kg}\cdot \hbox {yr}\) exposure of \(^{130}\hbox {Te}\) collected with the CUORE-0 experiment. In this work we exploit different topologies of coincident events to search for both the neutrinoless and two-neutrino double beta decay modes. We find no evidence for either mode and place lower bounds on the half-lives: \(T^{0\nu }_{0^+_1}>7.9\cdot 10^{23}\hbox {yr}\) and \(T^{2\nu }_{0^+_1}>2.4\cdot 10^{23}\hbox {yr}\) (\(90\%\,\hbox {CL}\)). Combining our results with those obtained by the CUORICINO experiment, we achieve the most stringent constraints available for these processes: \(T^{0\nu }_{0^+_1}>1.4\cdot 10^{24}\hbox {yr}\) and \(T^{2\nu }_{0^+_1}>2.5\cdot 10^{23}\hbox {yr}\) (\(90\%\,\hbox {CL}\)).