Perturbation Spectra of Warm Inflation in f(Q, T) Gravity

Abstract We investigate the warm inflationary scenario within the context of the linear version of f ( Q , T ) gravity, coupled with both the inflaton scalar field and the radiation field, under the conditions of the strong dissipation regime. First, we calculate the modified Friedmann equations and the modified slow-roll parameters. Subsequently, we apply the slow-roll approximations to derive the scalar power spectrum and the tensor power spectrum. Also, we develop formulations of the scalar and tensor perturbations for the f ( Q , T ) gravity with the warm inflation scenario. Furthermore, we scrutinize two different forms of the dissipation coefficient, a constant and a function of the inflaton field, to determine the scalar spectral index, the tensor-to-scalar ratio, and the temperature for the power-law potential case. By imposing some constraints on the free parameters of the model, we attain results in good agreement with both the Planck 2018 data and the joint Planck, BK15, and baryon acoustic oscillation data for the tensor-to-scalar ratio, and consistent results aligned with the Planck 2018 data for the scalar spectral index. In addition, the obtained results are within the range of observational data for the amplitude of the scalar power spectrum. Consequently, we are able to revive the power-law potential that was previously ruled out by observational data. Moreover, for both dissipation coefficients, the model leads to a scalar spectral index with the blue and red tilts in agreement with the Wilkinson Microwave Anisotropy Probe 3 yr data.