Zobrazeno 1 - 10
of 113
pro vyhledávání: '"Małkiewicz, Przemysław"'
Publikováno v:
Phys. Rev. D 110, 043512 (2024)
We propose a new method to investigate signatures of a quantum gravity phase in the primordial state of cosmological perturbations. We formulate and study a quantum model of a perturbed Friedmann-Lemaitre-Robertson-Walker universe beyond a tensor-pro
Externí odkaz:
http://arxiv.org/abs/2405.09307
Publikováno v:
Phys.Rev.D 109 (2024) 10, 106005
We study the non-unitary relation between quantum gravitational models defined using different internal times. We show that despite the non-unitarity, it is possible to provide a prescription for making unambiguous, though restricted, physical predic
Externí odkaz:
http://arxiv.org/abs/2401.06887
Publikováno v:
Phys. Rev. D 109, 083525 (2024)
We develop a relativistic framework to investigate the evolution of cosmological structures from the initial density perturbations to the highly nonlinear regime. Our approach involves proposing a procedure to match ``best-fit", exact Bianchi IX (BIX
Externí odkaz:
http://arxiv.org/abs/2401.05810
Publikováno v:
Phys. Rev. D 109, 023516 (2024)
We have discovered a class of dynamically stable coherent states for motion on the half-line. The regularization of the half-line boundary and the consequent quantum motion are expounded within the framework of covariant affine quantization, although
Externí odkaz:
http://arxiv.org/abs/2310.16868
Publikováno v:
Phys. Rev. D 108, 043534 (2023)
We study a semiclassical model of the mixmaster universe. We first derive the quantum model and then introduce its semiclassical approximation. We employ a general integral quantization method that respects the symmetries of the model given by the af
Externí odkaz:
http://arxiv.org/abs/2303.07873
Publikováno v:
Phys.Rev.D 109 (2024) 6, 066009
A quantum cosmological bouncing model may exhibit an ambiguity stemming from the nonclassical nature of the background evolution: two classically equivalent theories can produce two qualitatively different potentials sourcing the perturbations. We de
Externí odkaz:
http://arxiv.org/abs/2212.12484
Autor:
Boldrin, Alice, Małkiewicz, Przemysław
Publikováno v:
2023 Class. Quantum Grav. 40 015003
We develop a complete Hamiltonian approach to the theory of perturbations around any spatially homogeneous spacetime. We employ the Dirac method for constrained systems which is well-suited to cosmological perturbations. We refine the method via the
Externí odkaz:
http://arxiv.org/abs/2206.06926
We consider a simple cosmological model consisting of an empty Bianchi I Universe, whose Hamiltonian we deparametrise to provide a natural clock variable. The model thus effectively describes an isotropic universe with an induced clock given by the s
Externí odkaz:
http://arxiv.org/abs/2201.09138
Publikováno v:
Phys.Rev.D 105 (2022) 2, 023522
By quantising the background as well as the perturbations in a simple one fluid model, we show that there exists an ambiguity in the choice of relevant variables, potentially leading to incompatible observational physical predictions. In a classical
Externí odkaz:
http://arxiv.org/abs/2111.02963
Dirac procedure and the Hamiltonian formalism for cosmological perturbations in a Bianchi I universe
Autor:
Boldrin, Alice, Małkiewicz, Przemysław
Publikováno v:
2022 Class. Quantum Grav. 39 025005
We apply the Dirac procedure for constrained systems to the Arnowitt-Deser-Misner formalism linearized around the Bianchi I universe. We discuss and employ basic concepts such as Dirac observables, Dirac brackets, gauge-fixing conditions, reduced pha
Externí odkaz:
http://arxiv.org/abs/2105.05325