Two-neutrino ${\hat{I}}^2{\hat{I}}^2$ decay to excited states at next-to-leading order

Daniel Castillo, Dorian Frycz, Beatriz Benavente +1

We study two-neutrino double-beta decay ($2\hat{I}½{\hat{I}}^2{\hat{I}}^2$) into first-excited $0_2^{+}$ states of nuclei used in ${\hat{I}}^2{\hat{I}}^2$ decay experiments, including ${}^{76}$Ge, ${}^{82}$Se, ${}^{130}$Te, and $^…