Behavior of hadrons at finite density.: Lattice study of color SU(2) QCD

Using two-color lattice QCD with Wilson fermions, we report a study of the finite baryon number density system with two-flavors. First we investigate the Polyakov line and thermodynamical quantities in the (κ,μ) plane, where κ and μ are the hopping parameter and chemical potential in the fermion action, respectively. Then we calculate propagators of meson (q̄Γq) and baryon (qΓq) states. We find that the vector meson propagators are strongly modified in large μ regions, indicating the reduction of the mass. This anomalous behavior of the vector meson is observed for the first time in lattice QCD.