Self-sustained, out-of-equilibrium inflation

A bstract We use holography to study dS-invariant states of non-conformal, strongly coupled quantum field theories in four-dimensional de Sitter space. We show that out-of-equilibrium effects can sustain the exponential inflation within the regime of validity of semiclassical gravity, H ≪ M ≪ M sp , with H the Hubble parameter, M the characteristic scale of the quantum field theory, M sp = M p /N the species scale, M p the Planck scale, and N 2 the number of matter fields. In the holographic description, the required fine-tuning scales only logarithmically with the ratio M sp /H . The resulting solutions exhibit apparent horizons whose increasing area indicates a continuous growth of the comoving entropy density. We suggest that this inflationary regime can arise as the late-time limit of a dynamical evolution starting from an initial Friedmann–Lemaître–Robertson–Walker universe.