Chiral effective field theory approach to electromagnetic transitions in light nuclei

In this talk, I present a number of Quantum Monte Carlo calculations of electromagnetic transitions in $A\le 9$ nuclei, which account for two-body effects due to the coupling of external photons with pairs of interacting nucleons. Two-body electromagnetic currents have been recently derived from a chiral effective field theory that uses pions and nucleons as degrees of freedom. They include up to N3LO terms in the chiral expansion and consist of contact-like as well as one- and two-pion exchange operators. When used in combination with nuclear Hamiltonians that include two- and three-nucleon realistic potentials, two-body electromagnetic current operators are found to provide sizable contributions, which should not be neglected in a careful interpretation of experimental data.