``Electroweak interactions of nuclei''

Abstract: Electroweak interactions provide us with wonderful opportunities and challenges in nuclear physics, and this colloquium focuses on three recent advances regarding the modeling, computation, and understanding of such processes. (i) The neutron distribution of atomic nuclei can be probed via elastic neutrino scattering and via parity-violating electron scattering. Such experiments test virtual Z-boson exchange at very low momentum transfers and the inferred size of the neutron distribution (when compared with easy-to-measure charge distribution) constrains the nuclear equation of state, linking nuclei to neutron stars. (ii) Beta decays of nuclei happen at slower rates than what is expected from the beta decay of the free neutron. Ab initio computations of such processes show that this “quenching” of beta-decay rates is due to two-body currents and correlations, i.e. interaction effects between the decaying neutron and nearby nucleons. (iii) Neutrino-less double beta decay is probed world wide in experiments that search for physics beyond the standard model. If observed, a nuclear matrix element connects the lifetime of this decay with the neutrino-mass scale. The colloquium presents the challenges and advances in computations of this matrix element.