Existence and Uniqueness of Solutions of the Semiclassical Einstein Equation in Cosmological Models

@article{Meda2021ExistenceAU,
  title={Existence and Uniqueness of Solutions of the Semiclassical Einstein Equation in Cosmological Models},
  author={Paolo Meda and Nicola Pinamonti and Daniel Siemssen},
  journal={Annales Henri Poincar{\'e}},
  year={2021}
}
We prove existence and uniqueness of solutions of the semiclassical Einstein equation in flat cosmological spacetimes driven by a quantum massive scalar field with arbitrary coupling to the scalar curvature. In the semiclassical approximation, the backreaction of matter to curvature is taken into account by equating the Einstein tensor to the expectation values of the stress-energy tensor in a suitable state. We impose initial conditions for the scale factor at finite time, and we show that a… 
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