34 citations · 164 across the 13 of their papers we have counts for
15 papers
Cosmological de Sitter Solutions of the Semiclassical Einstein Equation
Hanno Gottschalk, Nicolai Rothe, Daniel Siemssen
Exponentially expanding space-times play a central role in contemporary cosmology, most importantly in the theory of inflation and in the Dark Energy driven expansion in the late u…
Special cosmological models derived from the semiclassical Einstein equation on flat FLRW space-times
Hanno Gottschalk, Nicolai Rothe, Daniel Siemssen
This article presents numerical work on a special case of the cosmological semiclassical Einstein equation (SCE). The SCE describes the interaction of relativistic quantum matter b…
Existence and uniqueness of solutions of the semiclassical Einstein equation in cosmological models
Paolo Meda, Nicola Pinamonti, Daniel Siemssen
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 coupli…
An Evolution Equation Approach to Linear Quantum Field Theory
Jan Dereziński, Daniel Siemssen
In the first part of our paper we analyze bisolutions and inverses of (non-autonomous) evolution equations. We are mostly interested in pseudo-unitary evolutions on Krein spaces, w…
The Cosmological Semiclassical Einstein Equation as an Infinite-Dimensional Dynamical System
Hanno Gottschalk, Daniel Siemssen
We develop a comprehensive framework in which the existence of solutions to the semiclassical Einstein equation (SCE) in cosmological spacetimes is shown. Different from previous w…
Pseudodifferential Weyl Calculus on (Pseudo-)Riemannian Manifolds
Jan Dereziński, Adam Latosiński, Daniel Siemssen
One can argue that on flat space the Weyl quantization is the most natural choice and that it has the best properties (e.g. symplectic covariance, real symbols corre…
Quantum Energy Inequalities in Pre-Metric Electrodynamics
Christopher J. Fewster, Christian Pfeifer, Daniel Siemssen
Pre-metric electrodynamics is a covariant framework for electromagnetism with a general constitutive law. Its lightcone structure can be more complicated than that of Maxwell theor…
An Evolution Equation Approach to the Klein-Gordon Operator on Curved Spacetime
Jan Dereziński, Daniel Siemssen
We develop a theory of the Klein-Gordon equation on curved spacetimes. Our main tool is the method of (non-autonomous) evolution equations on Hilbert spaces. This approach allows u…
Feynman Propagators on Static Spacetimes
Jan Dereziński, Daniel Siemssen
We consider the Klein-Gordon equation on a static spacetime and minimally coupled to a static electromagnetic potential. We show that it is essentially self-adjoint on $C_{\mathrm{…
Electromagnetic Potential in Pre-Metric Electrodynamics: Causal Structure, Propagators and Quantization
Christian Pfeifer, Daniel Siemssen
An axiomatic approach to electrodynamics reveals that Maxwell electrodynamics is just one instance of a variety of theories for which the name electrodynamics is justified. They al…
The Semiclassical Einstein Equation on Cosmological Spacetimes
Daniel Siemssen
The subject of this thesis is the coupling of quantum fields to a classical gravitational background in a semiclassical fashion. It contains a thorough introduction into quantum fi…
Enumerating Permutations by their Run Structure
Christopher J. Fewster, Daniel Siemssen
Motivated by a problem in quantum field theory, we study the up and down structure of circular and linear permutations. In particular, we count the length of the (alternating) runs…
Global Existence of Solutions of the Semiclassical Einstein Equation for Cosmological Spacetimes
Nicola Pinamonti, Daniel Siemssen
We study the solutions of the semiclassical Einstein equation in flat cosmological spacetimes driven by a massive conformally coupled scalar field. In particular, we show that it i…
Scale-Invariant Curvature Fluctuations from an Extended Semiclassical Gravity
Nicola Pinamonti, Daniel Siemssen
We present an extension of the semiclassical Einstein equations which couples n-point correlation functions of a stochastic Einstein tensor to the n-point functions of the quantum…
Hadamard States for the Vector Potential on Asymptotically Flat Spacetimes
Claudio Dappiaggi, Daniel Siemssen
We develop a quantization scheme for the vector potential on globally hyperbolic spacetimes which realizes it as a locally covariant conformal quantum field theory. This result all…