Article
Astronomy & Astrophysics
Yuri Makeenko
Summary: This article investigates the two-dimensional four-derivative conformal theory derived from the Nambu-Goto string by path-integration. By using the method of singular products, the author demonstrates that the one-loop approximation provides an exact solution. The solution can be conveniently described using minimal models, where the central charge c in the Kac spectrum depends on the parameters of the four-derivative action. This relation is nonlinear, allowing the mapping of the domain of physical parameters to c < 1, bypassing the KPZ barrier of the Liouville action.
Article
Physics, Particles & Fields
Song He, Hao Ouyang, Yuan Sun
Summary: In this work, we calculate the partition functions of N = 1 type 0A and 0B JT supergravity (SJT) on 2D surfaces of arbitrary genus with multiple finite cut-off boundaries, based on the T (T) over bar deformed super-Schwarzian theories. We compute the corresponding correlation functions in the T (T) over bar deformed matrix model side using topological recursion relations and the transformation properties of topological recursion relations under T (T) over bar deformation. We verify the matching of partition functions of finite cut-off 0A and 0B SJT on generic 2D surfaces with associated correlation functions in T (T) over bar deformed matrix models.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Astronomy & Astrophysics
Clifford Johnson
Summary: The proposed construction provides a complete definition for the family of Jackiw-Teitelboim supergravities, connecting to matrix models, using a combination of minimal string theories. This nonperturbative physics construction is stable and well-defined, revealing special properties for half-integer Gamma values in the supergravity models.
Article
Astronomy & Astrophysics
Martin Bojowald
Summary: This study examines the implementation of a modified form of gravity inspired by loop quantization, showing that a dedicated space-time analysis is still necessary even in the case of a bijective canonical transformation. Additionally, a global analysis of a recent proposal of a nonbijective transformation reveals that it does not preserve general covariance, with the only novel physical effect introduced being the presence of time-reversal hypersurfaces between classical space-time regions. These findings offer further insights into the physical interpretation of modified dynamics in models of loop quantum gravity.
Article
Computer Science, Interdisciplinary Applications
Jan Stolpp, Thomas Kohler, Salvatore R. Manmana, Eric Jeckelmann, Fabian Heidrich-Meisner, Sebastian Paeckel
Summary: Studying lattice models consisting of high-dimensional local degrees of freedom without global particle-number conservation is an important problem class in the field of strongly correlated quantum many body systems. These systems can't be analytically treated and require numerical methods, with matrix-product states serving as a flexible and generic ansatz class. Tailored methods are needed to truncate the dimension for efficient simulations.
COMPUTER PHYSICS COMMUNICATIONS
(2021)
Article
Astronomy & Astrophysics
J. Ambjorn, Y. Sato, Y. Watabiki
Summary: In a two-dimensional model of quantum gravity, the summation over all possible wormhole configurations leads to a Coleman mechanism in which the cosmological constant has no effect on large universes. Observers unable to observe changes in the topology will naturally interpret measurements of universe size as being caused by fluctuating cosmological constants rather than fluctuating spacetime topology.
Article
Physics, Particles & Fields
Luca Marchetti, Daniele Oriti, Andreas G. A. Pithis, Johannes Thuerigen
Summary: In tensorial group field theory (TGFT) approach, discrete building blocks of geometry are considered as the basic quanta, which are expected to generate continuum spacetime at a coarse-grained level through a phase transition. This study demonstrates how phase transitions can be realized in realistic TGFT models using Landau-Ginzburg mean-field theory. It provides insights into the phase transitions in TGFT models for quantum gravity and supports the extraction of effective cosmological dynamics from TGFTs.
JOURNAL OF HIGH ENERGY PHYSICS
(2023)
Article
Astronomy & Astrophysics
Klaus Liegener, Lukasz Rudnicki
Summary: In the lattice approach to loop quantum gravity on a fixed graph, explicit calculations are often complex and difficult to handle analytically. However, focusing on expectation values with respect to coherent states on the lattice, we have developed a step-by-step algorithm that simplifies computations and allows for analytical expressions with first-order corrections in the coherent state spread. This algorithm streamlines the process and makes it easily implementable for tackling advanced problems.
CLASSICAL AND QUANTUM GRAVITY
(2021)
Article
Physics, Particles & Fields
Luca Marchetti, Daniele Oriti, Andreas G. A. Pithis, Johannes Thurigen
Summary: In the tensorial group field theory approach to quantum gravity, phase transitions to continuum spacetime are shown to be possible in non-compact Lie groups and models including valued local degrees of freedom. By adapting the Landau-Ginzburg approach to mixed local/non-local degrees of freedom, the critical dimension for a Gaussian fixed point and continuous phase transition is determined. This represents an important step towards achieving a phase transition to continuum spacetime in realistic TGFT models for quantum gravity.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Astronomy & Astrophysics
S. N. Vergeles
Summary: The ground state of lattice quantum gravity differs significantly from the well-known vacua in quantum field theories such as QED, especially at small scales. The macroscopic Universe can only exist in the presence of fermion fields, leading to spontaneous PT symmetry breaking.
CLASSICAL AND QUANTUM GRAVITY
(2021)
Article
Multidisciplinary Sciences
Houri Ziaeepour
Summary: In this article, a new model for quantum gravity (QGR) and cosmology called SU(& INFIN;)-QGR is proposed and compared with other QGR proposals. The aim is to understand the common features and analogies among these models in order to gain a better understanding of gravity and the physical nature of spacetime. Common features identified include the importance of 2D structures, algebraic decomposition to tensor products, the special role of the SU(2) group, and the necessity of a quantum time as a relational observable.
Article
Chemistry, Multidisciplinary
Rene Steijl
Summary: The application of Quantum Computing (QC) to fluid dynamics simulation has become a popular research topic due to the potential of QC in speeding up simulations and enabling more detailed modeling. However, there are still many challenges in creating quantum algorithms for fluid modeling, particularly the non-linearity of governing equations. This study investigates the challenges and presents quantum circuits for lattice-based modeling of fluids, as well as a modular quantum-circuit implementation for non-linear terms in multi-dimensional lattice models. Preliminary analysis suggests that meaningful proof-of-concept experiments could be conducted in the near future with a sufficient number of fault-tolerant qubits.
APPLIED SCIENCES-BASEL
(2023)
Article
Physics, Multidisciplinary
Marco Finocchiaro, Daniele Oriti
Summary: The paper discusses the motivation and goals of renormalization analyses of group field theory models of simplicial 4d quantum gravity, reviews the current status of this research area, presents new computations of perturbative group field theories amplitudes, and suggests research directions for further progress.
FRONTIERS IN PHYSICS
(2021)
Article
Physics, Mathematical
Dimitrios Ampelogiannis, Benjamin Doyon
Summary: We examine the ergodic properties of quantum lattice models with short range interactions in the C* algebra formulation of statistical mechanics. We show that the long-time limit of ray-averaged observables along space-time rays converges to the n-th power of its expectation in the state, indicating ergodicity. We also demonstrate that in the GNS representation of the algebra of observables, the long-time limit of the ray average of any observable converges to the ensemble average times the identity along space-time rays of almost every speed, indicating a strong version of ergodicity.
COMMUNICATIONS IN MATHEMATICAL PHYSICS
(2023)
Article
Physics, Particles & Fields
Thomas G. Mertens
Summary: In this note, we propose a decomposition method for the quantum matrix group SLq+(2, R) by using the quantum algebra generators of Faddeev's modular double of U-q(sl(2, R)) as (deformed) exponentiation. The validity of this formula is confirmed through the relationship between hyperbolic representation matrices and the Whittaker function. We interpret (or derive) it in terms of Hopf duality and successfully construct the regular representation of the modular double, which leads to the Casimir and its modular dual resembling the Laplacian on the quantum group manifold. This description is significant for both 2d Liouville gravity and 3d pure gravity, as they are both governed by this algebraic structure. This result contributes to the formulation of q-BF amplitudes for both gravitational models.
JOURNAL OF HIGH ENERGY PHYSICS
(2023)
Article
Physics, Multidisciplinary
Fateme Rajabi, Kourosh Nozari
CANADIAN JOURNAL OF PHYSICS
(2019)
Article
Physics, Mathematical
M. Mardaani, K. Nozari
INTERNATIONAL JOURNAL OF GEOMETRIC METHODS IN MODERN PHYSICS
(2018)
Article
Astronomy & Astrophysics
Narges Rashidi, Kourosh Nozari
INTERNATIONAL JOURNAL OF MODERN PHYSICS D
(2018)
Article
Astronomy & Astrophysics
Narges Rashidi, Kourosh Nozari, Oyvind Gron
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2018)
Article
Physics, Mathematical
Kourosh Nozari, Naser Sadeghnezhad
INTERNATIONAL JOURNAL OF GEOMETRIC METHODS IN MODERN PHYSICS
(2019)
Article
Physics, Particles & Fields
M. Roushan, K. Nozari
EUROPEAN PHYSICAL JOURNAL C
(2019)
Article
Astronomy & Astrophysics
K. Nozari, P. Dehghani
Article
Physics, Multidisciplinary
Mohsen Khodadi, Kourosh Nozari, Anha Bhat, Sina Mohsenian
PROGRESS OF THEORETICAL AND EXPERIMENTAL PHYSICS
(2019)
Article
Physics, Multidisciplinary
Mohsen Khodadi, Kourosh Nozari
COMMUNICATIONS IN THEORETICAL PHYSICS
(2019)
Article
Physics, Particles & Fields
Kourosh Nozari, M. Hajebrahimi, M. Khodadi, A. Etemadi
EUROPEAN PHYSICAL JOURNAL C
(2019)
Article
Physics, Mathematical
S. Saghafi, K. Nozari, A. D. Kamali
INTERNATIONAL JOURNAL OF GEOMETRIC METHODS IN MODERN PHYSICS
(2019)
Article
Astronomy & Astrophysics
R. Shojaee, K. Nozari, F. Darabi
INTERNATIONAL JOURNAL OF MODERN PHYSICS D
(2020)
Article
Physics, Particles & Fields
M. Roushan, K. Nozari
EUROPEAN PHYSICAL JOURNAL C
(2020)
Article
Astronomy & Astrophysics
R. Shojaee, K. Nozari, F. Darabi
Summary: In this study, we investigated cosmological inflation in a Galileon inflationary model with the E-model potential to identify possible alpha-attractors. By analyzing the evolution of perturbations and considering the reheating phase post-inflation, we found universal values for the scalar spectral index and tensor-to-scalar ratio. Comparing our results with Planck data, we discovered constraints on the model's parameter space, including the potential for a longer reheating phase and observational viable values of ns associated with a larger temperature range.
INTERNATIONAL JOURNAL OF MODERN PHYSICS D
(2021)
Article
Astronomy & Astrophysics
Kourosh Nozari, Narges Rashidi
ASTROPHYSICAL JOURNAL
(2019)