Scalar-Torsion Cosmology in the Poincaré Gauge Theory of Gravity

We investigate the cosmological effect of the scalar-torsion (0+) mode in Poincaré gauge theory of gravity. We focus on two types of solutions distinguished by the constant curvature and kinetic energy. In the former, we find that the torsion EoS (w) varies with the background stage of the universe. In particular, it behaves like radiation (matter) of w=1/3 (w=0) in the radiation (matter) dominant era. But eventually in the late time the torsion density becomes a de Sitter universe for the acceleration universe. In the latter, our numerical analysis indicates that the EoS has an asymptotic behavior in the high redshift regime. We also employ theoretical calculations together with numerical computations in accordance with such asymptotic phenomenon.