Nuclear and particle physicists study fundamental interactions for two basic reasons: to clarify the nature of the most elementary pieces of matter and determine how they fit together and interact. Most of what has been learned so far is embodied in the Standard Model of particle physics, a framework that has been both repeatedly validated by experimental results and is widely viewed as incomplete.
Nuclear physicists have focused on key questions that target the plethora of unresolved issues:
What are the absolute masses of neutrinos and how have they shaped the evolution of the universe?
Are neutrinos their own antiparticles?
Why is there more matter than antimatter in the present universe?
What are the unseen forces that disappeared from view as the universe expanded and cooled?
Rare isotopes produced at FRIB's will provide excellent opportunities for scientists to devise experiments that look beyond the Standard Model and search for subtle indications of hidden interactions and minutely broken symmetries and thereby help refine the Standard Model and search for new physics beyond it.
Sources: 2015 Long Range Plan for Nuclear Science