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Quantum Gravity: Motivations and Alternatives [PDF]
, 2009 The mutual conceptual incompatibility between General Relativity and Quantum Mechanics / Quantum Field Theory is generally seen as the most essential motivation for the development of a theory of Quantum Gravity.
Hedrich, Reiner
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Journal of High Energy Physics, 2020 A massive, nonrelativistic scalar field in an expanding spacetime is usually approximated by a pressureless perfect fluid, which leads to the standard conclusion that such a field can play the role of cold dark matter.
Borna Salehian +2 more
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Causality bounds on scalar-tensor EFTs
Journal of High Energy Physics, 2023 We compute the causality/positivity bounds on the Wilson coefficients of scalar-tensor effective field theories. Two-sided bounds are obtained by extracting IR information from UV physics via dispersion relations of scattering amplitudes, making use of ...
Dong-Yu Hong +2 more
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Spacetime and the Philosophical Challenge of Quantum Gravity [PDF]
, 2001 We survey some philosophical aspects of the search for a quantum theory of gravity, emphasising how quantum gravity throws into doubt the treatment of spacetime common to the two `ingredient theories' (quantum theory and general relativity), as a 4 ...
Butterfield, Jeremy +3 more
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On scalar and vector fields coupled to the energy-momentum tensor
Journal of High Energy Physics, 2018 We consider theories for scalar and vector fields coupled to the energy-momentum tensor. Since these fields also carry a non-trivial energy-momentum tensor, the coupling prescription generates self-interactions. In analogy with gravity theories, we build
Jose Beltrán Jiménez +2 more
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Quantum gravity fluctuations in the timelike Raychaudhuri equation
Journal of High Energy Physics, 2023 We consider a timelike geodesic congruence in the presence of perturbative quantum fluctuations of the spacetime metric. We calculate the change in the volume of a bundle of geodesics due to such fluctuations and thereby obtain a quantum-gravitationally ...
Sang-Eon Bak +3 more
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Teleparallel Theories of Gravity: Illuminating a Fully Invariant Approach [PDF]
, 2019 Teleparallel gravity and its popular generalization $f(T)$ gravity can be formulated as fully invariant (under both coordinate transformations and local Lorentz transformations) theories of gravity.
Coley, A. A. +9 more
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Tree-level scattering amplitudes in nonlocal field theories
Journal of High Energy Physics, 2021 We prove in two ways that, for a special class of nonlocal field theories consistent with linear and non-linear stability at the classical level, and with unitarity and super-renormalizability or finiteness at the quantum level, the n-point tree-level ...
Leonardo Modesto, Gianluca Calcagni
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Classical Gauge Theory of Gravity
Theoretical and Mathematical Physics, 2002 The classical theory of gravity is formulated as a gauge theory on a frame bundle with spontaneous symmetry breaking caused by the existence of Dirac fermionic fields. The pseudo-Riemannian metric (tetrad field) is the corresponding Higgs field. We consider two variants of this theory.
openaire +3 more sources
The philosophy behind quantum gravity [PDF]
, 2006 This paper investigates some of the philosophical and conceptual issues raised by the search for a quantum theory of gravity. It is critically discussed whether such a theory is necessary in the first place, and how much would be accomplished if it is ...
Zinkernagel, Henrik +2 more
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