  We propose a new framework for investigating two-flavor lattice QCD with
finite temperature and density by applying the Karsten-Wilczek lattice fermion,
in which a species-dependent imaginary chemical potential can reduce the number
of species to two without losing chiral symmetry. This lattice discretization
is useful for study on finite-(T,\mu) QCD since its discrete symmetries are
appropriate for the case. To show its applicability, we study strong-coupling
lattice QCD with temperature and chemical potential. We derive the effective
potential of the scalar meson field and obtain a critical line of the chiral
phase transition, which is qualitatively consistent with the phenomenologically
expected phase diagram.
