Inflation in R plus R2 gravity with torsion

We examine an inflationary model in R + R-2 gravity with torsion, where R-2 denotes five independent quadratic curvature invariants; it turns out that only two free parameters remain in this model. We show that the behavior of the scale factor a(t) is determined by two scalar fields, axial torsion chi(t) and the totally anti-symmetric curvature E(t), which satisfy two first-order differential equations. Considering chi approximate to 0 during inflation leads to a power-law inflation: a similar to (t + A)(p) where 1 < p <= 2, and the constant A is determined by the initial values of E, chi and the two parameters. After the end of inflation, chi and E will enter into an oscillatory phase.