The Optical Potential: From Structure to Reactions and Back Again*

Nuclear reaction theory describes collisions between two or more nuclear species and plays an important twofold role in the context of low -energy nuclear physics. First, it connects experimental observables obtained at accelerated-beam facilities with specific aspects of nuclear structure. Second, it addresses processes that are essential for a variety of applications in nuclear astrophysics, nuclear energy, medicine, security, and industry. In its first role, it is essential to unlock the full discovery potential of FRIB, ATLAS, and the ARUNA labs; in the latter, it is at the basis of a successful implementation of the corresponding applications. Within this context, the nucleon-nucleus effective interaction, a.k.a the Optical Potential (OP) plays a pivotal role, being an essential ingredient of most theoretical accounts of nuclear reactions. Therefore, establishing the connection between the OP and the underlying nuclear structure will contribute significantly to achieve an important goal of nuclear physics: the unification of structure and reactions theory.