Abstract In this contribution we present two studies of fundamental symmetries in light nuclei: the investigation of CP violation via the calculation of the electric dipole moments (EDMs) of the deuteron, 3 H and 3 He, and the possible existence of a new bosonic particle, the so-called X17, in the 3 H( p , e + e − ) 4 He and 3 He( n , e + e − ) 4 He reactions. The advantage to perform these investigations in few-nucleon systems is related to the possibility to compute accurate ab initio bound- and continuum-states wave functions using well established nuclear interactions. Therefore, if these effects are observed, they can be unambiguously related to underlying beyond Standard Model theories.