Two-neutrino $\beta \beta$ decay to excited states at next-to-leading order

Daniel Castillo, Dorian Frycz, Beatriz Benavente +1

We study two-neutrino double-beta decay ($2\nu \beta \beta$) into first-excited $0_2^{+}$ states of nuclei used in $\beta \beta$ decay experiments, including ${}^{76}$Ge, ${}^{82}$Se, ${}^{130}$Te, and $^{136}…