Constraint on inflation model from BICEP2 and WMAP 9-year data
  Even though Planck data released in 2013 (P13) is not compatible with
Background Imaging of Cosmic Extragalactic Polarization (B2) and some local
cosmological observations, including Supernova Legacy Survey (SNLS) samples and
$H_0$ prior from Hubble Space Telescope (HST) etc, Wilkinson Microwaves
Anisotropy Probe 9-year data (W9) is consistent with all of them in the base
six-parameter $\Lambda$CDM+tensor cosmology quite well. In this letter, we
adopt the combinations of B2+W9 and B2+W9+SNLS+BAO+HST to constrain the
cosmological parameters in the base six-parameter $\Lambda$CDM+tensor model
with $n_t=-r/8$, where r and $n_t$ are the tensor-to-scalar ratio and the tilt
of relic gravitational wave spectrum, and BAO denotes Baryon Acoustic
Oscillation. We find that the Harrison-Zel'dovich (HZ) scale invariant scalar
power spectrum is consistent with both data combinations, chaotic inflation is
marginally disfavored by the data at around $2\sigma$ level, but the power-law
inflation model and the inflation model with inverse power-law potential can
fit the data nicely.
