Description
The scalar spectral index, ns, plays a central role in testing inflationary models, with its precise value shaping theoretical and observational priorities. Recent analyses combining the latest cosmic microwave background (CMB) and baryon acoustic oscillation (BAO) data suggest a shift toward higher ns values compared to the Planck results. This comes with implications for inflation; previously preferred models appear to be now disfavoured by the data (>2 sigma). In this talk, I explore how this shift in ns arises due to differences between CMB and BAO data and caution against interpreting joint constraints in the context of inflation, until this emerging CMB-BAO tension is resolved.
