Featuring the primordial power spectrum: new constraints on interrupted
  slow-roll from CMB and LRG data
  Using the most recent data from the WMAP, ACT and SPT experiments, we update
the constraints on models with oscillatory features in the primordial power
spectrum of scalar perturbations. This kind of features can appear in models of
inflation where slow-roll is interrupted, like multifield models. We also
derive constraints for the case in which, in addition to cosmic microwave
observations, we also consider the data on the spectrum of luminous red
galaxies from the 7th SDSS catalog, and the SNIa Union Compilation 2 data. We
have found that: (i) considering a model with features in the primordial power
spectrum increases the agreement with data with the respect of the featureless
"vanilla" LCDM model by Delta(chi^2) ~ 7; (ii) the uncertainty on the
determination of the standard parameters is not degraded when features are
included; (iii) the best fit for the features model locates the step in the
primordial spectrum at a scale k ~ 0.005 Mpc^-1, corresponding to the scale
where the outliers in the WMAP7 data at ell=22 and ell=40 are located.; (iv) a
distinct, albeit less statistically significant peak is present in the
likelihood at smaller scales, with a Delta(chi^2) ~ 3.5, whose presence might
be related to the WMAP7 preference for a negative value of the running of the
scalar spectral index parameter; (v) the inclusion of the LRG-7 data do not
change significantly the best fit model, but allows to better constrain the
amplitude of the oscillations.
