38 citations · 291 across the 27 of their papers we have counts for
29 papers
A Cuscuton Representation of the Loop Quantum Cosmology Bounce
Niayesh Afshordi, Kristina Giesel
Loop Quantum Cosmology (LQC) replaces the big bang singularity of the homogeneous universe by a bounce, usually described by the modified Friedmann equation $H^2=ρ(1-ρ/ρ_c)/(3M_p^2…
Robustness of the primordial power spectrum in hybrid loop quantum cosmology to approximations near the bounce
Kristina Giesel, Almudena Guillén, Guillermo A. Mena Marugán +1
We prove the robustness of the analytic approximation used in (hybrid) loop quantum cosmology to compute the primordial power spectrum of the cosmological perturbations for a recen…
Generalising gravitationally induced decoherence beyond linear environmental interactions in a microscopic quantum mechanical toy model
Max Joseph Fahn, Renata Ferrero, Kristina Giesel +1
We generalise the quantum mechanical toy model for gravitationally induced decoherence presented in Xu, Blencowe (2022) and Domi et al. (2024). In contrast to earlier formulations,…
Formation of shell-crossing singularities in effective gravitational collapse models with bounded and unbounded polymerizations
Francesco Fazzini, Kristina Giesel, Eric Rullit
We extend the investigation into the formation of shell-crossing singularites (SCS) in effective polymerized LTB models to the LQG-inspired asymmetric bounce model, as well as to e…
Investigation of the gravitational dust collapse of the LQG-inspired effective asymmetric bounce model
Kristina Giesel, Hongguang Liu, Eric Rullit
We investigate gravitational dust collapse within an effective loop quantum gravity (LQG)-inspired model exhibiting an asymmetric bounce in the marginally bound case. This work ext…
A gravitationally induced decoherence model for photons in the context of the relational formalism
Max Joseph Fahn, Kristina Giesel, Roman Kemper
We formulate a model of gravitationally induced decoherence for photons starting from Maxwell theory coupled to linearised gravity, expressed in terms of Ashtekar-Barbero variables…
From Principles to Effective Models: A Constructive Framework for Effective Covariant Actions with a Unique Vacuum Solution
Kristina Giesel, Hongguang Liu
The absence of Birkhoff's theorem in effective quantum gravity models leads to a fundamental ambiguity in the vacuum sector, where a priori no unique vacuum solution exists. As a r…
Linking Edge Modes and Geometrical Clocks in Linearized Gravity
Kristina Giesel, Viktoria Kabel, Wolfgang Wieland
Reference frames are crucial for describing local observers in general relativity. In quantum gravity, different proposals exist for how to treat reference frames. There are models…
Gravitationally induced decoherence of a scalar field: investigating the one-particle sector and its interplay with renormalisation
Max Joseph Fahn, Kristina Giesel
We investigate the one-particle sector for the field-theoretical model of gravitationally induced decoherence for a scalar field in [1] with a special focus on the renormalisation…
Regular black holes and their relationship to polymerized models and mimetic gravity
Kristina Giesel, Hongguang Liu, Parampreet Singh +1
We present further applications of the formalism introduced by the authors in arXiv:2308.10949, which allows embedding of a broad class of generalized LTB models into effective sph…
Understanding gravitationally induced decoherence parameters in neutrino oscillations using a microscopic quantum mechanical model
Alba Domi, Thomas Eberl, Max Joseph Fahn +5
In this work, a microscopic quantum mechanical model for gravitationally induced decoherence introduced by Blencowe and Xu is investigated in the context of neutrino oscillations.…
Generalized analysis of a dust collapse in effective loop quantum gravity: fate of shocks and covariance
Kristina Giesel, Hongguang Liu, Parampreet Singh +1
Based on modifications inspired from loop quantum gravity (LQG), spherically symmetric models have recently been explored to understand the resolution of classical singularities an…
Embedding generalized LTB models in polymerized spherically symmetric spacetimes
Kristina Giesel, Hongguang Liu, Eric Rullit +2
We generalize the existing works on the way (generalized) LTB models can be embedded into polymerized spherically symmetric models in several aspects. We re-examine such an embeddi…
Dynamically implementing the -scheme in cosmological and spherically symmetric models in an extended phase space model
Kristina Giesel, Hongguang Liu
We consider an extended phase space formulation for cosmological and spherically symmetric models in which the choice of a given -scheme can be implemented dynamically.…
Spherical symmetric gravitational collapse of a dust cloud: polymerized dynamics in reduced phase space
Kristina Giesel, Muxin Han, Bao-Fei Li +2
Based on the effective dynamics in the scheme of the spherical symmetry reduced model in the reduced phase space formulation of loop quantum gravity (LQG), we investigate…
An open scattering model in polymerized quantum mechanics
Kristina Giesel, Michael Kobler
We derive a quantum master equation in the context of a polymerized open quantum mechanical system for the scattering of a Brownian particle in an ideal gas environment. The model…
A gravitationally induced decoherence model using Ashtekar variables
Max Joseph Fahn, Kristina Giesel, Michael Kobler
We consider the coupling of a scalar field to linearised gravity and derive a relativistic gravitationally induced decoherence model using Ashtekar variables. The model is formulat…
On consistent gauge fixing conditions in polymerized gravitational systems
Kristina Giesel, Bao-Fei Li, Parampreet Singh +1
For classical gravitational systems the lapse function and the shift vector are usually determined by imposing appropriate gauge fixing conditions and then demanding their preserva…
Analysing (cosmological) singularity avoidance in loop quantum gravity using U coherent states and Kummer's functions
Kristina Giesel, David Winnekens
Using a new procedure based on Kummer's Confluent Hypergeometric Functions, we investigate the question of singularity avoidance in loop quantum gravity (LQG) in the context of U$(…
Non-singular quantum gravitational dynamics of an LTB dust shell model: the role of quantization prescriptions
Kristina Giesel, Bao-Fei Li, Parampreet Singh
We study some consequences of the loop quantization of the outermost dust shell in the Lemaître-Tolman-Bondi spacetime with a homogeneous dust density using different quantization…
Relating dust reference models to conventional systems in manifestly gauge invariant perturbation theory
Kristina Giesel, Bao-Fei Li, Parampreet Singh
Models with dust reference fields in relational formalism have proved useful in understanding the construction of gauge-invariant perturbation theory to arbitrary orders in the can…
Towards a reduced phase space quantization in loop quantum cosmology with an inflationary potential
Kristina Giesel, Bao-Fei Li, Parampreet Singh
We explore a reduced phase space quantization of loop quantum cosmology (LQC) for a spatially flat FLRW universe filled with reference fields and an inflaton field in a Starobinsky…
Mukhanov-Sasaki equation in manifestly gauge-invariant linearized cosmological perturbation theory with dust reference fields
Kristina Giesel, Laura Herold, Bao-Fei Li +1
The aim of this article is to understand the role of dust reference fields, often also called clocks, on cosmological perturbations around a flat FLRW universe. We derive the Mukha…
Coherent States on the Circle: Semiclassical Matrix Elements in the Context of Kummer Functions and the Zak transformation
Kristina Giesel, David Winnekens
We extend former results for coherent states on the circle in the literature in two ways. On the one hand, we show that expectation values of fractional powers of momentum operator…