Name: Chih-Hung Wang
 Institution: Department of Physics, Tamkang University
 Title: Torsion effects in the early Universe
 Key Words: torsion; inflation; quadratic curvature
 Abstract: In many well-known theories of gravity, e.g. Einstein-Cartan gravity and Poincare gauge theory of gravity, gravitational fields are described by metric and metric-compatible connection with torsion. Although torsion tensor has 24 components in a general Riemann-Cartan space-time, it reduces to 2 components in the homogeneous and isotropic Universe. It is our question to understand the effects of these two functions in cosmological models. Our recently work has showed that quantum effects in the background space-time with torsion contain quadratic curvature terms so these quadratic terms become significant in the early Universe. In this talk, we present a cosmological model including quadratic curvature terms and show that there do exist a power-law inflation due to these torsion effects. A reheating process will also be discussed.