Phases of Strongly Interacting Matter - from quarks and gluons to atomic nuclei and neutron stars

An important guiding theme of modern nuclear, particle and astrophysics is the exploration of the phase diagram emerging from the Strong Interaction sector within the Standard Model of elementary particles: from quarks and gluons to the formation of composite structures such as nucleons and nuclei, including the dynamical generation of their masses. The starting point and well established theoretical framework for this research area is Quantum Chromodynamics (QCD), its symmetries and symmetry breaking sce- narios. This colloquium describes how such symmetry principles, in particular the almost exact chiral symmetry of the lightest quarks, translate into effective field theories that establish the interface between QCD and nuclear physics. Phase transitions of strongly interacting matter are discussed in this context, and it is demonstrated how such a theoretical framework confronts large varieties of empirical data. The presentation ends with new results and constraints concerning properties of highly compressed baryonic matter in the center of neutron stars.