Speaker
Description
Determinations of the effective Majorana mass from the neutrinoless double beta decay half-life depend on precise calculations of nuclear matrix elements (NMEs) of decay operators. These NMEs have a leading two-body component given by long-ranged (neutrino exchange), medium-ranged (pion exchange), and short-ranged (contact) contributions. Three-nucleon operators are, in most cases, not included in these calculations. It is important to determine the size of their impact on the NMEs. To this end, we derived three-nucleon operators within a delta-full chiral effective field theory up to next-to-next-to-leading order in the Weinberg power counting. We calculated the NMEs of these operators in light nuclei using quantum Monte Carlo methods to estimate their impact relative to the two-nucleon contributions. These three-body operators can then be implemented into other many-body methods to calculate more precise half-lives in systems of experimental interest to double beta decay searches.
