Scalar perturbations in two-scalar-field warm inflation
Abstract
We investigate scalar perturbations in a two-scalar-field cosmological model unifying warm inflation, dark matter, and dark energy. The inflaton is noncanonically coupled to a second scalar field that acts as dark energy at late times. Assuming negligible dissipation and perturbations of the dark-energy field, we derive the linear scalar perturbations in a gauge-ready form, including quantum and thermal noise in the inflaton sector and stochastic fluctuations of the energy transfer to radiation. We numerically solve the coupled perturbation system using a Fokker-Planck formalism and compute the scalar spectral index ns and the tensor-to-scalar ratio r for dissipation coefficients scaling as Tp with p=−1, 1 and $3$. For p=−1, we find scenarios compatible with current CMB observations in both the weak and strong dissipative regimes, while the explored scenarios with p=1 and $3$ are outside the observationally supported regions. Compared with standard single-field warm inflation, the two-scalar-field model yields a systematically larger spectral index for a given tensor-to-scalar ratio.
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BibTeX
@misc{luongo2026scalar,
title = {{Scalar perturbations in two-scalar-field warm inflation}},
author = {Orlando Luongo and Tommaso Mengoni and Paulo M. Sá},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.07193},
eprint = {2611.07193},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.07193},
}
RIS
TY - UNPB
TI - Scalar perturbations in two-scalar-field warm inflation
AU - Orlando Luongo
AU - Tommaso Mengoni
AU - Paulo M. Sá
PY - 2026
DA - 2026/11/04
PB - arXiv
DO - 10.48550/arxiv.2611.07193
UR - https://arxiv.org/abs/2611.07193
AB - We investigate scalar perturbations in a two-scalar-field cosmological model unifying warm inflation, dark matter, and dark energy. The inflaton is noncanonically coupled to a second scalar field that acts as dark energy at late times. Assuming negligible dissipation and perturbations of the dark-energy field, we derive the linear scalar perturbations in a gauge-ready form, including quantum and thermal noise in the inflaton sector and stochastic fluctuations of the energy transfer to radiation. We numerically solve the coupled perturbation system using a Fokker-Planck formalism and compute the scalar spectral index n_s and the tensor-to-scalar ratio r for dissipation coefficients scaling as T^p with p=−1, 1 and $3$. For p=−1, we find scenarios compatible with current CMB observations in both the weak and strong dissipative regimes, while the explored scenarios with p=1 and $3$ are outside the observationally supported regions. Compared with standard single-field warm inflation, the two-scalar-field model yields a systematically larger spectral index for a given tensor-to-scalar ratio.
ER -