Exploring cold and dense matter from two-color QCD: Numerical experiments and effective models

We investigate properties in cold and dense two-color QCD by means of a linear sigma model, where the numerical experiments from lattice simulations are straightforwardly doable, particularly focusing on the mean fields, hadron mass spectrum, and topological susceptibility. As a result, in addition to the emergence of the baryon superfluidity and the restoration of chiral symmetry, a possibility of the enhancement of the U(1) axial anomaly effects is found. Our analysis also indicates that non-negligible diquark-source effects can prevent us from achieving clear understandings of those symmetry properties. Investigation in two-color QCD is expected to provide useful information on cold and dense properties in the real-life QCD with powerful lattice simulations.