Quark Matter In Low Temperature And High Density

The behavior of matter at high quark density and (comparatively) low temperature is interesting in itself and is relevant to phenomena in the early universe, in neutron stars, and in heavy-ion collisions. Important progress in understanding the behavior of quark matter in the region has been achieved recently, by adopting the techniques and concept of condensed matter theory. Because QCD is asymptotically free, matter at ultra-high densities and/or temperatures will consist of almost-free quarks and gluons, the combination of asymptotic freedom and BCS theory make a rigorous analysis possible. They provide a theoretical laboratory within chiral symmetry breaking and confinement can be studied at weak coupling.The quark-quark interaction mediated by one-gluon exchange is attractive in color antitriplet channel. Therefore Matter at sufficiently small temperature will take the form of a color superconductivity, in which there is a condensate of Cooper pairs of quarks near the Fermi surface. Over the last few years it has become clear that there is a rich and varied landscape of phases lying between these asymptotic regimes and the familiar hadronic phases at low temperature and high density. At sufficiently high densities, where treating the three flavor quarks (up, down, strange) as massless is reasonable, the original color and flavor symmetries of three-flavor QCD, namely su(3)_color×SU(3)_L×SU(3)_R, is suggested to be broken down to a diagonal subgroup SU(3)_color+L+R via theBardeen-Cooper-Schrieffer (BCS) pairing [1]. The three-flavor quark matter with the particular symmetry is called the "color-flavor locking", which is very likely the ground state for the color superconductivity. But when quark chemical potential μ decreases, strange quark mass M_S will presumably increase, which play a crucial role in the phase transition of QCD and can not be ignored.In the thesis, we will analyze the mechanism of the form of the color superconductivity and discuss its property from two aspect : theoretical and phenomenal. Because the presence of a chemical potential...