In this project, theoretical models will be developed to understand recent advances and discoveries in nuclear physics and to predict possible new ones. For collisions of nuclei with very different proton and neutron numbers at current accelerators and planned Facility for Rare Isotope Beams (FRIB), the relativistic transport model based on the relativistic mean-field model will be extended to include realistic initial nuclear distributions and different mean-field potentials for protons and neutrons, and then used to study the dependence of the energy of nuclear matter on its density and proton to neutron ratio via the two-nucleon correlation functions, the production of light nuclear clusters, the relative diffusion between protons and neutrons, and the ratios of various particles. For ultrarelativistic heavy-ion collisions at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC), the strong gluon fields generated in the collisions and the quasi-particle nature of the quarks and gluons will be incorporated in the multiphase transport model that includes both initial interactions among quarks and gluons and final interactions among ordinary hadrons as well as the transition between these two phases of matters. The resulting comprehensive model will be used to study the signatures and properties of the quark-gluon plasma through the collective dynamics of produced particles, the electromagnetic radiations during the collisions, the abundance of particles that consist of heavy quarks, and the energy loss of very energetic particles produced from initial hard collisions. For nuclear reactions induced by photons at the Thomas Jefferson National Laboratory (JLAB), effective hadronic models will be used to study the production mechanism and properties of both known and missing baryon resonances. The project has the intellectual merit of not only impacting directly the research programs at the three major nuclear physics facilities FRIB, RHIC, and JLAB in the U.S. but also contributing to the understanding of many important issues in astro- and particle physics. It also has the broader impact of providing participating young students and postdoctoral researchers a broad research experience that would prepare them well for careers in either nuclear science or other areas to continue their contributions to the scientific and technological advance in our society.