Neutrinoless double-beta decay is the most promising process for the revelation of the Majorana nature of neutrinos and the violation of the total lepton number.
The decay rate depends not only on the neutrino Majorana mass (and/or other BSM contributions), but also on the nuclear matrix element and on the axial coupling g_A.
The calculation of the nuclear matrix elements is a difficult task and has been done so far with large uncertainties.
The possible quenching of g_A is an open problem.
In this mini workshop we will discuss the status and prospects of the existing and planned nuclear calculations.