Scalar-Torsion Mode in a Cosmological Model of the Poincar\'{e} Gauge Theory of Gravity

摘要

We investigate the equation of state (EoS) of the scalar-torsion mode inPoincar\'{e} gauge theory of gravity. We concentrate on two cases with theconstant curvature solution and positive kinetic energy, respectively. In theformer, we find that the torsion EoS has different values in the various stagesof the universe. In particular, it behaves like the radiation (matter) EoS of$w_r=1/3$ ($w_m=0$) in the radiation (matter) dominant epoch, while in the latetime the torsion density is supportive for the accelerating universe. In thelatter, our numerical analysis shows that in general the EoS has an asymptoticbehavior in the high redshift regime, while it could cross the phantom divideline in the low redshift regime.