Constraints on single-field inflation with WMAP, SPT and ACT data -- A last-minute stand before Planck

Understand

We constrain models of single field inflation with the pre-\textit{Planck} CMB data.

• The data used here is the 9-year Wilkinson Microwave Anisotropy Probe (\textit{WMAP}) data, South Pole Telescope (SPT) data and Atacama Cosmology Telescope (ACT) data.
• By adding in running of spectral index parameter, we find that the $\chi^2$ is improved by a factor of $\Delta \chi^2=8.44$, which strongly indicates the preference of this parameter from current data.
• In addition, we find that the running of spectral index $\alpha_s$ does not change very much even if we switch to different pivot scales, which suggests that the power law expansion of power spectrum is accurate enough till the 1st order term.