Torsion and accelerating expansion of the universe in quadratic gravitation

Understand

Several exact cosmological solutions of a metric-affine theory of gravity with two torsion functions are presented.

• These solutions give a essentially different explanation from the one in most of previous works to the cause of the accelerating cosmological expansion and the origin of the torsion of the spacetime.
• These solutions can be divided into two classes.
• The solutions in the first class define the critical points of a dynamical system representing an asymptotically stable de Sitter spacetime.