Oral Presentation

The BAO-CMB Tension and Implications for Inflation (Virtual)

Author(s): Elisa Ferreira (Kavli IPMU)

Presenter: Elisa Ferreira (Kavli IPMU)

Combining cosmological probes is one of the most powerful approaches in modern cosmology. However, a clear tension emerges when certain CMB datasets are combined with DESI DR2 BAO measurements. One manifestation of this tension appears in the scalar spectral index ns, whose inferred value shifts to higher values relative to CMB-only analyses, making several well-motivated inflationary models appear disfavored at the level. In this talk, I will present the BAO–CMB tension, focusing in particular on ACT DR6 and SPT-3G, and show how it propagates into the combined constraint on ns. I will then discuss the implications of this shift for inflationary model selection and emphasize the value of carefully examining consistency between datasets when interpreting joint constraints.