Abstract: Basic questions such as the quantum nature of neutrinos or the origin of the matter-antimatter asymmetry in the universe, remain as big open challenges for physics. The yet undiscovered 0νββ decay is sensitive to the way of describing neutrinos and more fundamentally to the symmetries of nature. Due to this unique potential an eager experiental search is underway.
In order to plan these searches, reliable estimations for the decay lifetimes, which are known to exceed 10^26 yr, are crucial as well as to extract precise new physics parameters or constrains from these experiments. However, the nuclear matrix elements -a theory input that must be calculated- are not well known, as state-of-the-art nuclear structure methods disagree in their predictions.
In this seminar, I will revisit a physics process known since quite long ago, double-gamma decay (γγ), but from a new perspective: providing valuable insights into neutrinoless double-beta decay (0νββ) nuclear matrix elements.