Experimental prospects for double gamma decays from double-beta decay emitters

The yet undiscovered neutrinoless double beta decay (0νββ) has a unique physics potential [1]. It is sensitive to the way of describing neutrinos, helping to establish whether neutrinos are their own antiparticles, and more fundamentally to the symmetries of nature, since its observation constitute a laboratory probe of lepton number violation. The nuclear matrix element, a key factor that enters in the prediction of the 0νββ-decay rate, must be calculated in a reliable and systematically improvable way.

The recent relation found between double gamma decay from the double isobaric analog state (DIAS) of the initial double beta decay nucleus and 0νββ decay within several nuclear structure methods [2,3], will help to constrain the values of 0νββ nuclear matrix elements from a measurement of double gamma decay in a less model dependent way. In this talk I will present the potential of measuring this double gamma decay to provide new insights on , and the first steps towards its experimental measurement. Despite being a second order electromagnetic decay from a high excited state above particle emission threshold, our preliminary results [4] support the feasibility of its measurements for current spectroscopic detector technologies.



[1] M. Agostini, G. Benato, J. A. Detwiler, J. Menéndez, F. Vissani, Rev. Mod. Phys. 95, 025002 (2023).

[2] B. Romeo, J. Menéndez, and C. Peña-Garay, Phys. Lett. B 827, 136965 (2022).

[3] L. Jokiniemi and J. Menéndez, Phys. Rev. C 107, 044316 (2023).

[4] B. Romeo, D. Stramaccioni, J. Menéndez and J.J. Valiente-Dobón, in preparation.