Neutrinoless double beta decay (0νββ) is a proposed decay which turns out to be the most promising process
to observe lepton number violation in the laboratory and to establish the nature of neutrinos, namely whether they are Dirac or Majorana particles. Due to this unique potential, a very active experimental program aims to detect this rare decay. In order to plan these searches, reliable estimations for the decay lifetimes, which are known to exceed $10^{26}$y, are crucial as well as to extract precise new physics parameters or constrains from these experiments. The nuclear matrix elements (NMEs), a key input in such predictions, are not well known and first attemps to produce ab initio results with controlled uncertainties are underway.
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 how the measurement of electromagnetic transitions, could help in deriving a more reliable nuclear matrix element. Particularly, I will present our study of the relation between double magnetic dipole transitions from the double isobaric analog state with 0νββ-decay NMEs, and how this could be used to constrain 0νββ NMEs from measurements of nuclear 2γ M1M1 decays.
J.J. Valiente Dobón