Reconciling Nonminimally Coupled Higgs Inflation with ACT DR6 Observations through Reheating

Understand

The Higgs inflation model with nonminimal coupling, while disfavored by the 1$\sigma$ region of the latest Atacama Cosmology Telescope Data Release 6 (ACT DR6) observational data, can be reconciled with the ACT DR6 data by incorporating the effects of reheating.

• In this paper, we consider reheating with a constant equation of state $w_{re}$.
• For the strong coupling case $\xi=100$, we find that reconciling the model with both the ACT DR6 constraints and the minimum reheating temperature required for successful Big Bang Nucleosynthesis (BBN) demands $w_{re} \geq 0.92$.
• Specifically, the reheating $e$-folding number must be $ N_{ re}= 28.3$ for $w_{ re} = 0.92$, and within $24.9 \leq N_{ re} \leq 27.2$ for $w_{ re} = 1$.