| Name: Sanghati Saha |
| Affiliation: Institute of Mathematical Sciences |
| Conference ID: ASI2026_965 |
| Title: Warm Multi-Natural Inflation: The Primordial Power Spectrum and the prediction for $(n_s, r)$ from Planck, ACT, and SPT |
| Abstract Type: Poster |
| Abstract Category: Galaxies and Cosmology |
| Author(s) and Co-Author(s) with Affiliation: Sanghati Saha(Institute of Mathematical Sciences,Chennai, 600113, India) |
| Abstract: We perform a study of warm inflation in the framework of Palatini gravity with an $R+ \alpha R^2$ extension, investigating how different classes of scalar-field potentials behave with dissipative dynamics and CMB observations. We consider axion-motivated natural and multi-natural forms, and analyze each model under two representative temperature-dependent dissipation coefficients: a linear form $\Upsilon \propto T$ and a cubic form $\Upsilon \propto T^{3}/\phi^{2}$. Within the Palatini formulation, where the $R^2$ term modifies the inflationary dynamics without introducing an additional scalar degrees of freedom, we compute the background evolution and primordial curvature power spectrum for both the potential--dissipation combination. The strength of dissipation is characterized by the dimensionless ratio $Q \equiv \Upsilon/(3H)$, which provides a uniform classification of the weak ($Q \ll 1$) and strong ($Q \gtrsim 1$) warm-inflation regimes across the different models considered. We have computed the inflationary observables from \textit{Planck}~2018, ACT, and SPT. We have found that warm dissipation systematically enlarges the observationally allowed parameter space relative to the cold-inflation limit. The constraints on scalar spectral index $n_s$ play an important role in discriminating early universe inflationary models, as our predicted values depend on both the inflaton potential and the strength of dissipative effects during inflation. Here, we have constrained the palatini gravity parameter $\alpha$ as well. In addition to highlighting the importance of Palatini modified gravity and warm-inflation dynamics in addressing early-Universe physics with observations, our results show that current CMB data set significant constraints on the dissipation ratio $Q$. |
