Nonminimal coupling in light of ACT data

doi:10.1016/j.dark.2025.102106

Nonminimal coupling in light of ACT data

2025-09-27

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DOI：10.1016/j.dark.2025.102106

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The latest ACT data release disfavors the attractor ns=1−2/N. In inflationary models with nonminimal coupling, such attractors typically arise in the strong coupling limit. To align with observational constraints, we focus on nonminimal coupling models with small coupling constants. For the model with the coupling function Ω(ϕ)=1+ξf(ϕ) and the potential V(ϕ)=λ2f2(ϕ), we find that observational data constrain the parameters as 0.1≲ξ≲35 and 0≲k≲1.5 for f(ϕ)=ϕk at the 1σ confidence level. With the help of the nonminimal coupling Ω(ϕ)=1+ξϕ2, the hilltop inflation and power-law inflation models with power indices 2/3 and 1/3 can be consistent with observational data within the 1σ range. We also give the viable parameter regions of ξ for these three models.

Nonminimal coupling in light of ACT data

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