Electromagnetic transitions from isobaric analogue states to study nuclear matrix elements for double beta decays and astro-neutrino inverse beta decays

Experimental studies for nuclear matrix elements (NMEs) for neutrinoless double beta decays (DBDs) and astro-neutrino inverse beta decays (IBDs) are crucial for neutrino studies beyond the standard model and the astro neutrino reactions since theoretical model calculations for the NMEs are hard due to the high sensitivities of the NMEs to the models. The NMEs associated with DBDs and IBDs are found for the first time to be studied experimentally by measuring electro-magnetic (gamma) transitions from isobalic analogue states (IASs) of the DBD and IBD nuclei. They are used to help the theoretical model calculations for them. The IAS gamma cross sections and the event rates are estimated to show the feasibility of the experiments.