Double gamma transitions and their relation with neutrinoless double beta decay by Beatriz Romeo

By Beatriz Romeo (Donostia International Physics Center & Laboratorio Subterráneo de Canfranc) Neutrinoless double-beta (0νββ) decay is a proposed nuclear decay which turns out to be the most promising process to observe lepton number violation in the laboratory, and to establish whether neutrinos are its own antiparticle. Due to this unique potential, several international collaborations are actively searching for this rare decay, among them the NEXT experiment running at the Canfranc Underground Laboratory, in the Spanish Pyrenees. In order to plan these searches, estimations for the decay lifetimes, which are known to exceed 10^26 years, are crucial. However, the decay rate depends quadratically on nuclear matrix elements (NMEs) which are not well known, as state-of-the-art nuclear structure methods predict NMEs disagreeing by factors 2-3. An alternative avenue to learn about 0νββ NMEs is to find other observables correlated with 0νββ decay that may be easier to access experimentally. In this seminar, I will discuss results for double dipole magnetic (M1M1) transitions, which show a good correlation with 0νββ decay. This could be used to constrain 0νββ NMEs from measurements of nuclear 2γ M1M1 decays.