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In the approach of Causal Dynamical Triangulations (CDT), quantum gravity is obtained as a scaling limit of a non-perturbative path integral over space-times whose causal structure plays a crucial role in the construction. After some…

General Relativity and Quantum Cosmology · Physics 2018-11-30 L. Glaser , R. Loll

In this short note we review a recently found formulation of two-dimensional causal quantum gravity defined through Causal Dynamical Triangulations and stochastic quantization. This procedure enables one to extract the nonperturbative…

High Energy Physics - Theory · Physics 2014-11-20 J. Ambjorn , R. Loll , W. Westra , S. Zohren

We study a formulation of lattice gravity defined via Euclidean dynamical triangulations (EDT). After fine-tuning a non-trivial local measure term we find evidence that four-dimensional, semi-classical geometries are recovered at long…

High Energy Physics - Theory · Physics 2017-01-25 J. Laiho , S. Bassler , D. Coumbe , D. Du , J. T. Neelakanta

In the non-relativistic theory of gravitation recently proposed by Horava, the Hamiltonian constraint is not a local equation satisfied at each spatial point but an equation integrated over a whole space. The global Hamiltonian constraint…

High Energy Physics - Theory · Physics 2011-09-29 Shinji Mukohyama

The formalism of causal dynamical triangulations (CDT) provides us with a non-perturbatively defined model of quantum gravity, where the sum over histories includes only causal space-time histories. Path integrals of CDT and their continuum…

General Relativity and Quantum Cosmology · Physics 2008-11-26 J. Ambjorn , R. Loll , W. Westra , S. Zohren

Causal dynamical triangulations (CDT) constitute a background independent, nonperturbative approach to quantum gravity, in which the gravitational path integral is approximated by the weighted sum over causally well-behaving simplicial…

High Energy Physics - Theory · Physics 2011-02-24 T. Trzesniewski

In this note we searched for a family of solutions with Caustic singularity in non relativistic-renormalizable Ho$\check {\textbf{r}}$ava-Lifshitz (HL)theory without the general covariant. We show that in infrared (IR) limit and with a…

High Energy Physics - Theory · Physics 2011-12-30 M. R. Setare , D. Momeni

We study the continuum limit of a "radially reduced" approximation of Causal Dynamical Triangulations (CDT), so-called multigraph ensembles, and explain why they serve as realistic toy models to study the dimensional reduction observed in…

High Energy Physics - Theory · Physics 2013-02-15 Georgios Giasemidis , John F. Wheater , Stefan Zohren

We formulate a non-perturbative lattice model of two-dimensional Lorentzian quantum gravity by performing the path integral over geometries with a causal structure. The model can be solved exactly at the discretized level. Its continuum…

High Energy Physics - Theory · Physics 2009-10-31 J. Ambjorn , R. Loll

This thesis investigates low-dimensional models of nonperturbative quantum gravity, with a special focus on Causal Dynamical Triangulations (CDT). We define the so-called curvature profile, a new quantum gravitational observable based on…

General Relativity and Quantum Cosmology · Physics 2023-11-14 Joren Brunekreef

To solve the path integral for quantum gravity, one needs to regularise the space-times that are summed over. This regularisation usually is a discretisation, which makes it necessary to give up some paradigms or symmetries of continuum…

General Relativity and Quantum Cosmology · Physics 2014-09-30 Lisa Glaser

We calculate the spectral dimension for a nonperturbative lattice approach to quantum gravity, known as causal dynamical triangulations (CDT), showing that the dimension of spacetime smoothly decreases from approximately 4 on large distance…

High Energy Physics - Theory · Physics 2015-04-21 D. N. Coumbe , J. Jurkiewicz

Previous work has shown that the macroscopic structure of the theory of quantum gravity defined by causal dynamical triangulations (CDT) is compatible with that of a de Sitter universe. After emphasizing the strictly nonperturbative nature…

High Energy Physics - Theory · Physics 2011-05-09 J. Ambjorn , A. Gorlich , J. Jurkiewicz , R. Loll , J. Gizbert-Studnicki , T. Trzesniewski

Causal Dynamical Triangulations (CDT) is a lattice formulation of quantum gravity, suitable for Monte-Carlo simulations which have been used to study the phase diagram of the model. It has four phases characterized by different dominant…

High Energy Physics - Lattice · Physics 2022-05-04 J. Ambjorn , J. Gizbert-Studnicki , A. Görlich , D. Németh

In the non-relativistic theory of gravity recently proposed by Horava, the Hamiltonian constraint is not satisfied locally at each point in space. The absence of the local Hamiltonian constraint allows the system to have an extra…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 Tsutomu Kobayashi , Yuko Urakawa , Masahide Yamaguchi

We extend the 2 dimensional Causal Dynamical Triangulation (CDT) model from the usual model of closed string to the one of open-closed string. The matrix-vector model describing the loop gas model is modified so as to possess the nature of…

High Energy Physics - Theory · Physics 2014-01-16 Hiroshi Kawabe

Curvature is a key notion in General Relativity, characterizing the local physical properties of spacetime. By contrast, the concept of curvature has received scant attention in nonperturbative quantum gravity. One may even wonder whether…

General Relativity and Quantum Cosmology · Physics 2023-06-27 R. Loll

We report a holographic study of a two-dimensional dilaton gravity theory with the Dirichlet boundary condition for the cases of non-vanishing and vanishing cosmological constants. Our result shows that the boundary theory of the…

High Energy Physics - Theory · Physics 2020-01-08 Su-Kuan Chu , Chen-Te Ma , Chih-Hung Wu

We compare the effective action of the scale factor obtained from lattice quantum gravity (in the form of Causal Dynamical Triangulations (CDT)) to the corresponding effective action obtained from the simplest Functional Renormalization…

High Energy Physics - Lattice · Physics 2025-09-26 Jan Ambjørn , Jakub Gizbert-Studnicki , Andrzej Gőrlich , Dániel Németh

In this paper we continue the study of the Hamiltonian formalism of the healthy extended Horava-Lifshitz gravity. We find the constraint structure of given theory and argue that this is the theory with the second class constraints. Then we…

High Energy Physics - Theory · Physics 2014-11-20 J. Kluson