Refined predictions for Starobinsky inflation and post-inflationary constraints in light of ACT

Recent measurements from the Atacama Cosmology Telescope (ACT), combined with Planck and DESI data, suggest a higher value for the spectral index n s . This places Starobinsky inflation at the edge of the 2 σ constraints for a number of e-folds N ⋆ around 60 when using the usual analytical approximations. We present refined predictions for Starobinsky inflation that go beyond the commonly used analytical approximations. By evaluating the model with these improved expressions, we show that for N ⋆ ≳ 58 it remains consistent with current observational constraints at the 2 σ level. Additionally, we examine the implications of the ACT results for post-inflationary reheating parameters. Specifically, we find a…

• DF
  Deutsche Forschungsgemeinschaft

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