Constraints on the extensions to the base ACDM model from BICEP2, Planck and WMAP

Recently Background Imaging of Cosmic Extragalactia Polarization (B2) discovered the relic gravitational waves at 7.0 sigma confidence level. However, the other cosmic microwave background (CMB) data, for example Planck data released in 2013 (P13), prefer a much smaller amplitude of the primordial gravitational waves spectrum if a power-law spectrum of adiabatic scalar perturbations is assumed in the six-parameter ACDM cosmology. In this paper, we explore whether the wCDM model and the running spectral index can relax the tension between B2 and other CMB data. Specifically we found that a positive running of running of spectral index is preferred at 1.7 sigma level from the combination of B2, P13 and WMAP Polarization data.