arXiv subjects

Morgane König

Publications and source records attributed to Morgane König.

4 recordsLinked to original sources

arXiv2025

Finite-Temperature Instantons from First Principles

We derive the finite-temperature quantum-tunneling rate from first principles. The rate depends on both real- and imaginary-time; we demonstrate that the relevant instantons should therefore be defined on a Schwinger-Keldysh contour, and how the familiar Euclidean-time result arises from it in the limit of large physical times. We generalize previous results for general initial states, and identify distinct behavior in the high- and low-temperature limits, incorporating effects from background fields. We construct a consistent perturbative scheme that incorporates large finite-temperature effects.

hep-th↗

arXiv2024

Elastic Scattering of Cosmological Gravitational Wave Backgrounds: Primordial Black Holes and Stellar Objects

Primordial black holes (PBHs) are plausible dark matter candidates that formed from the gravitational collapse of primordial density fluctuations. Current observational constraints allow asteroid-mass PBHs to account for all of the cosmological dark matter. We show that elastic scattering of a cosmological gravitational wave background, these black holes generate spectral distortions on the background of 0.3% for cosmologically relevant frequencies without considering coherent scattering and 5% when the coherent enhancement is included. Scattering from stellar objects induce much smaller distortions. Detectability of this signal depends on our ultimate understanding of the unperturbed background spectrum.

gr-qc↗

arXiv2023

An SZ-Like Effect on Cosmological Gravitational Wave Backgrounds

Cosmological gravitational wave backgrounds (CGWBs) are the conglomeration of unresolved gravitational wave signals from early Universe sources, which make them a promising tool for cosmologists. Because gravitons decouple from the cosmic plasma early on, one can consider interactions between gravitons and any particle species that were present in the very early Universe. We show that analogous to the cosmic microwave background, elastic scattering on any cosmological background will induce small distortions in its energy density spectrum. We then quantify the magnitude of these spin-dependent spectral distortions when attributed to the dark matter in the early Universe. Lastly, we give estimates for potentially measurable distortions on CGWBs due to gravitational scattering by primordial black holes.

gr-qc↗

arXiv2020

On Hybrid Monodromy Inflation (Hic Sunt Dracones)

We revisit two-field hybrid inflation as an effective field theory for low-scale inflation with sub-Planckian scalar field ranges. We focus on a prototype model by Stewart because it allows for a red spectral tilt, which still fits the current data. We describe the constraints on this model imposed by current CMB measurements. We then explore the stability of this model to quantum corrections. We find that for relevant, marginal, and at least a finite set of irrelevant operators, some additional mechanism is required to render the model stable to corrections from both quantum field theory and quantum gravity. We outline a possible mechanism by realizing the scalars as compact axions dual to massive $4$-form field strengths, and outline how natural hybrid inflation may be supported by strong dynamics in the dual theory.

hep-th↗