Upper: posterior distribution for n_s for the base ΛCDM model (black) compared to the posterior when a tensor component and running scalar spectral index are added to the model (red) Middle: constraints (68% and 95%) in the n_s–dn_s/ dlnk plane for ΛCDM models with running (blue) and additionally with tensors (red). Lower: constraints (68% and 95%) on n_s and the tensor-to-scalar ratio r_0.002 for ΛCDM models with tensors (blue) and additionally with running of the spectral index (red). The dotted line show the expected relation between r and n_s for a V(φ) ∝ φ² inflationary potential (Eqs. (65a) and (65b)); here N is the number of inflationary e-foldings as defined in the text. The dotted line should be compared to the blue contours, since this model predicts negligible running. All of these results use the Planck+WP+highL data combination.