Tachyonic instabilities from post-inflation curvature reorganization via quadratic Gauss-Bonnet coupling produce the observed dark matter relic density across wide mass and scale ranges, backed by lattice simulations and a fitting function.
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Semiclassicality and Decoherence of Cosmological Perturbations
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abstract
Transition to the semiclassical behaviour and the decoherence process for inhomogeneous perturbations generated from the vacuum state during an inflationary stage in the early Universe are considered both in the Heisenberg and the Schr\"odinger representations to show explicitly that both approaches lead to the same prediction: the equivalence of these quantum perturbations to classical perturbations having stochastic Gaussian amplitudes and belonging to the quasi-isotropic mode. This equivalence and the decoherence are achieved once the exponentially small (in terms of the squeezing parameter $r_k$) decaying mode is neglected. In the quasi-classical limit $|r_k|\to \infty$, the perturbation mode functions can be made real by a time-independent phase rotation, this is shown to be equivalent to a fixed relation between squeezing angle and phase for all modes in the squeezed-state formalism. Though the present state of the gravitational wave background is not a squeezed quantum state in the rigid sense and the squeezing parameters loose their direct meaning due to interaction with the environment and other processes, the standard predictions for the rms values of the perturbations generated during inflation are not affected by these mechanisms (at least, for scales of interest in cosmological applications). This stochastic background still occupies a small part of phase space.
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Graviton quantum fluctuations smear the light cone in a state-dependent way that regularizes UV singularities in scalar field one-loop diagrams.
Stochastic effects in multifield inflation make the number of fields relevant for e-fold statistics and power spectrum, with a general formula for higher moments and an upper bound on fields for successful inflation.
Derives stochastic equations from Schwinger-Keldysh formalism that include quantum diffusion and classical metric perturbations for non-perturbative ultra-slow-roll inflation, validated on Starobinsky and critical Higgs models.
citing papers explorer
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Tachyonic gravitational dark matter production after inflation
Tachyonic instabilities from post-inflation curvature reorganization via quadratic Gauss-Bonnet coupling produce the observed dark matter relic density across wide mass and scale ranges, backed by lattice simulations and a fitting function.
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Squeezed Gravitons and One-Loop Self-Energy under Light-Cone Smearing
Graviton quantum fluctuations smear the light cone in a state-dependent way that regularizes UV singularities in scalar field one-loop diagrams.
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Multifield stochastic inflation: Relevance of number of fields in statistical moments
Stochastic effects in multifield inflation make the number of fields relevant for e-fold statistics and power spectrum, with a general formula for higher moments and an upper bound on fields for successful inflation.
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Nonperturbative stochastic inflation in perturbative dynamical background
Derives stochastic equations from Schwinger-Keldysh formalism that include quantum diffusion and classical metric perturbations for non-perturbative ultra-slow-roll inflation, validated on Starobinsky and critical Higgs models.
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