OICC Press Journal of Theoretical and Applied Physics 2251-7235 6 1 2023 11 17 Linear energy-momentum tensor for a scalar field in de Sitter space 10.1186/2251-7235-6-24 EN Mohammad Reza Tanhayi Department of Physics, Faculty of Basic Science, Islamic Azad University Central Tehran Branch (IAUCTB), P.O. Box 14676‑86831, Tehran, Iran 0000-0003-0907-4842 Sepideh Mirabi Department of Physics, Islamic Azad University Journal Article 2023 11 17 AbstractIn this work, under a small perturbation of the background metric with the squeezing of other fields (scalar field in our case), the linear form of the energy-momentum tensor is calculated in terms of the perturbation factor. The linear form of the Klein-Gordon equation for a scalar field with both minimally and conformally coupled cases in de Sitter and flat metrics are also calculated.