Results 21 to 30 of about 6,189 (307)
No Page curves for the de Sitter horizon
Journal of High Energy Physics, 2022 We investigate the fine-grained entropy of the de Sitter cosmological horizon. Starting from three-dimensional pure de Sitter space, we consider a partial reduction approach, which supplies an auxiliary system acting as a heat bath both at I $$ \mathcal ...
Joshua Kames-King +2 more
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NEW SPIN FOAM MODELS OF QUANTUM GRAVITY [PDF]
Modern Physics Letters A, 2005 We give a brief and a critical review of the Barret-Crane spin foam models of quantum gravity. Then we describe two new spin foam models which are obtained by direct quantization of General Relativity and do not have some of the drawbacks of the Barret-Crane models.
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Renormalizable and Unitary Lorentz Invariant Model of Quantum Gravity [PDF]
Universe, 2021 We analyze the R+R2 model of quantum gravity where terms quadratic in the curvature tensor are added to the General Relativity action. This model was recently proved to be a self-consistent quantum theory of gravitation, being both renormalizable and unitary.
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Gravity as an ensemble and the moment problem
Journal of High Energy Physics, 2021 If a bulk gravitational path integral can be identified with an average of partition functions over an ensemble of boundary quantum theories, then a corresponding moment problem can be solved. We review existence and uniqueness criteria for the Stieltjes
Oliver Janssen +2 more
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Solving puzzles in deformed JT gravity: phase transitions and non-perturbative effects
Journal of High Energy Physics, 2021 Recent work has shown that certain deformations of the scalar potential in Jackiw-Teitelboim gravity can be written as double-scaled matrix models. However, some of the deformations exhibit an apparent breakdown of unitarity in the form of a negative ...
Clifford V. Johnson, Felipe Rosso
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Phenomenology of low quantum gravity scale models [PDF]
Physical Review D, 1999 We study some phenomenological implications of models where the scale of quantum gravity effects lies much below the four-dimensional Planck scale. These models arise from M-theory vacua where either the internal space volume is large or the string coupling is very small.
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q -deformed spin foam models of quantum gravity [PDF]
Classical and Quantum Gravity, 2007 We numerically study Barrett-Crane models of Riemannian quantum gravity. We have extended the existing numerical techniques to handle q-deformed models and arbitrary space-time triangulations. We present and interpret expectation values of a few selected observables for each model, including a spin-spin correlation function which gives insight into the
Khavkine, Igor, Christensen, J. Daniel
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Journal of High Energy Physics, 2021 We study the genus expansion on compact Riemann surfaces of the gravitational path integral Z grav m $$ {\mathcal{Z}}_{\mathrm{grav}}^{(m)} $$ in two spacetime dimensions with cosmological constant Λ > 0 coupled to one of the non-unitary minimal models ...
Dionysios Anninos, Beatrix Mühlmann
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An effective matrix model for dynamical end of the world branes in Jackiw-Teitelboim gravity
Journal of High Energy Physics, 2022 We study Jackiw-Teitelboim gravity with dynamical end of the world branes in asymptotically nearly AdS2 spacetimes. We quantize this theory in Lorentz signature, and compute the Euclidean path integral summing over topologies including dynamical branes ...
Ping Gao +2 more
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Quantum singularities in a model of f(R) gravity [PDF]
The European Physical Journal C, 2012 The formation of a naked singularity in a model of f(R) gravity having as source a linear electromagnetic field is considered in view of quantum mechanics. Quantum test fields obeying the Klein-Gordon, Dirac and Maxwell equations are used to probe the classical timelike naked singularity developed at r=0.
Gürtuğ, Özay +2 more
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