Playing with QCD I: effective field theories. Fourth lecture

Lattice QCD is just starting to explore the finite density region, still far away from the high-density low-temperature sector. pQCD at finite density seems to provide sensible results, even for not so large values of μ. Mass and gap effects provide important contributions to the EoS near the critical region. The phase diagram can be very rich in the high-μ sector, with different possibilities for pairing and color superconductivity. Astrophysical measurements are becoming increasingly precise, and will start killing models soon. Some signatures (for strange, quark or hybrid neutron stars) are still very similar, though. The interior of compact stars is a very rich and intricate medium, which may contain all sorts of condensates as well as deconfined quark matter. (author)