Observational and theoretical status of tachyon inflation in teleparallel gravity

The idea of inflation is of an essential importance in modern cosmology and solves the flatness, horizon and magnetic monopole problems. Recently, serious observational constraints have been applied on inflationary models which made some of them excluded. Many models have been extensively constructed to describe the inflationary epoch. One of the observationally consistent models is tachyon field coupled to gravity. In this talk, we will discuss a new inflationary model in which tachyonic field is used in teleparallel gravity. we will consider the case where there is no coupling between tachyonic field and the scalar torsion (f(φ) = 1 or any constant), and argue that for tachyonic field in open string theory and D-brane theory and also tachyonic potentials consistent with Noether's theorem, tachyonic field is a proper candidate for inflation. We will continue with talking about inflation of tachyons in the framework of f(T) and will consider the state in which f(φ) = 1 to show that one can find approximately n_s= 0.956 for the spectral index, and r = 0.0061 for tensor to the scalar ratio. The calculated r from tachyonic model agrees with the upper limited value obtained by Planck results.