Speaker
Description
Many models of inflation and the early universe provide specific predictions for the values of the scalar spectral index $n_s$ and its running, $\alpha_s$. Considering current data from ACT DR6, Planck, SPT-3G DR1, and DESI DR2 it was found that key models of inflation, including the Starobinsky model, were ruled out at $2\sigma$. However we find that when additionally varying the number of light relativistic species (i.e. $N_\mathrm{eff}$), these models are no longer ruled out. We also find that future CMB experiments such as the Simons Observatory and CMB-HD would be able to rule out these inflation models with high confidence, even when varying these additional degenerate parameters. We validate our forecasts using both CAMB and CLASS, finding agreement in forecasted parameter errors to within 6% and spectra within 0.5% for multipoles up to $\ell = 20000$.