Take up the challenge for a single field inflation after BICEP2

Abstract

The measurement of the tensor-to-scalar ratio r shows a very powerful constraint to theoretical inflation models through the detection of B-mode. In this paper, we propose a single inflation model with infinity power series potential called the Infinity Power Series (IPS) inflation model, which is well consistent with latest observations from Planck and BICEP2. Furthermore, it is found that in the IPS model, the absolute value running of the spectral index increases while the tensor-to-scalar ratio becomes large, namely both large r ≈0.20 and \vert n_s'\vert≳ {O}(10^-2) are realized in the IPS model. In the meanwhile, the number of e-folds is also big enough N≈50-60 to solve the problems in Big Bang cosmology.