Cosmological Model Of The Non-minimal Coupling F(T) Gravity

By the observations of type Ia Supernovae,cosmic microwave background,large scalar structure and baryon acoustic oscillation,it is suggested that our Universe is now in an acceleration phase of expansion.And this acceleration is no doubt one of the most intriguing problems in current physics research.To explain this problem,many theories and models have been proposed,including the cosmological constant model as the simplest one.However,this simplest scenario has to face two problems,the fine-tuning problem and the coincidence problem.Hence,two main directions for the alternative scenarios have been considered.One is to introduce “dark energy” in the framework of general relativity.The other is to modify the gravitational term,such as f(R)gravity.For decades many theories and models have been proposed from this two directions,including f(T)gravity,which is a modified gravity based on the Teleparallel Equivalent of General Relativity.There is an important advantage that the equations of motion of f(T)gravity are second order instead of fourth order in f(R)gravity.Recently an extension to f(T)gravity,named the non-minimal torsion-matter coupling f(T)gravity,has also been proposed,which may has some new cosmological properties.In this thesis,we study a generalized power-law torsion-matter coupling f(T)model.The main contents of this thesis are as follows.In Sections 2,we briefly review the standard cosmology model and dark energy models.In Sections 3,we review the non-minimal torsion-matter coupling f(T)gravity.The model and its cosmological fit are given in Sec.4.We use dynamical system analysis,statefinder diagnostics and Om diagnostics to investigate our model in Secs.5.Finally,Sec.6 contains our summary.