Article
Astronomy & Astrophysics
Shen-Shi Du, Lin Lan, Jun-Jie Wei, Zi-Min Zhou, He Gao, Lu-Yao Jiang, Bin-Bin Zhang, Zi-Ke Liu, Xue-Feng Wu, En-Wei Liang, Zong-Hong Zhu
Summary: The spectral lags of gamma-ray bursts have been considered as a potential method to test Lorentz invariance violations, with a new approach proposed to directly fit the spectral-lag behavior of a GRB to determine intrinsic time lag and quantum-gravity energy scales. A global fitting analysis of GRB 190114C using a Bayesian approach shows strong evidence for spectral-lag transitions and provides robust constraints on LIV coefficients, albeit somewhat weaker than existing bounds. Further observations of GRBs with higher-energy emissions and temporal resolutions are expected to refine intrinsic time lag formulation and strengthen LIV constraints in the photon sector.
ASTROPHYSICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
Luca Marchetti, Daniele Oriti
Summary: This research derives effective dynamics for scalar cosmological perturbations from quantum gravity in the framework of group field theory condensate cosmology. It establishes a connection between fundamental quantum gravity models and cosmological observations.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Steffen Gielen, Luca Marchetti, Daniele Oriti, Axel Polaczek
Summary: We propose a new method for obtaining an effective FLRW cosmology based on group field theory, in which macroscopic observables are directly used as the basis for formulating dynamics. By applying this method to constrained quantum systems, we obtain a kinematical phase space of expectation values and moments without the need for a clock variable. We identify a gauge fixing that allows us to rewrite the effective dynamics in relational form and discuss the necessary conditions for compatibility with classical FLRW cosmology.
CLASSICAL AND QUANTUM GRAVITY
(2022)
Article
Astronomy & Astrophysics
Pietro Dona
Summary: Local flatness is a shared property of all spin foam models, ensuring that the building blocks of the theory are flat by requiring locally-trivial parallel transport. In the context of simplicial Lorentzian spin foam theory, local flatness is shown to be the main factor in the emergence of geometry, independent of the specific spin foam model details. The asymptotic analysis of the Engle-Pereira-Rovelli-Livine spin foam amplitudes in the regime of large quantum numbers is discussed, highlighting the interplay with local flatness.
Article
Astronomy & Astrophysics
Frank Saueressig, Amir Khosravi
Summary: This article studies the impact of the intriguing feature shared by many quantum gravity programs, the dynamic decrease of the spectral dimension, on the energy loss of static, spherically symmetric black holes due to Hawking radiation. The study shows that the decrease in the spectral dimension renders the luminosity of a black hole finite, but this mechanism is insufficient to generate long-lived black hole remnants.
Article
Astronomy & Astrophysics
Seth K. Asante, Bianca Dittrich, Hal M. Haggard
Summary: This study presents the first computation of spin foam dynamics that acts as a test of the quantum equations of motion of gravity. The results reveal a rich semiclassical regime, but emphasize the need to understand the interplay between various parameters. Additionally, the subtle nature of the semiclassical regime is shown to be a generic feature of path integral quantization of systems with second class constraints.
CLASSICAL AND QUANTUM GRAVITY
(2021)
Article
Astronomy & Astrophysics
Andreas Mantziris, Tommi Markkanen, Arttu Rajantie
Summary: Based on current experimental data, it is predicted that the vacuum state of the Universe is metastable, leading to a non-zero rate of vacuum decay. Research shows that considering the standard model and the vacuum state during inflation, a lower bound on an unknown parameter can be obtained. This bound is stronger than in single field inflation models without Higgs-inflaton coupling.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Johannes Muench
Summary: This paper presents a strategy to generalize eternal models to dynamical collapse models through surface matching, based on assumptions about the static quantum black hole spacetime outside collapsing matter, homogeneity of the collapsing matter, and differentiability at the surface of the matter. The paper discusses the junction conditions and spacetime dynamics for bouncing black hole spacetimes proposed by loop quantum gravity, with explicit solutions provided for a recent model. The analysis reveals the collapse and re-expansion of matter, challenging the concept of an infinite tower of Penrose diagrams proposed by some LQG models.
CLASSICAL AND QUANTUM GRAVITY
(2021)
Article
Astronomy & Astrophysics
Cong Zhang
Summary: In this research, the loop quantum theory is applied to the spherically symmetric model of gravity coupled to Gaussian dust fields to study the quantum features of black holes. By utilizing the path integral formulation, the quantum dynamics are investigated and an effective action is obtained to describe the continuous description of the quantum lattice system. The derived Hamiltonian in this study differs from the classical Hamiltonian with the holonomy correction for macro black holes, requiring a sufficiently fine lattice structure.
Article
Physics, Particles & Fields
Adel Bilal, Corinne de Lacroix, Harold Erbin
Summary: We study the effective gravitational action for 2D massive Euclidean fermions, finding that the m(2) order gravitational action contains a piece characteristic of the Mabuchi action and several non-local terms.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Physics, Particles & Fields
Deepak Vaid, Devadharsini Suresh
Summary: This article discusses a new method for calculating scattering amplitudes in quantum field theory, based on the discovery of the amplituhedron in scattering of massless gauge bosons. It also mentions the challenges faced by Loop Quantum Gravity and its correspondence with LQG.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Multidisciplinary Sciences
Damiano Anselmi
Summary: In this paper, the concept of purely virtual particles and their uses in quantum gravity, primordial cosmology, and collider physics are reviewed. The introduction of fakeons, which mediate interactions without appearing among the incoming and outgoing states, is discussed. The paper also explores the classical limit of a theory with physical particles and fakeons, as well as the implications of quantum gravity for primordial cosmology and new physics beyond the standard model.
Article
Astronomy & Astrophysics
Sandeep Aashish, Sukanta Panda, Abbas Altafhussain Tinwala, Archit Vidyarthi
Summary: In this work, the calculation of the divergent part of one-loop covariant effective action for scalar fields coupled to gravity was developed using the generalized Schwinger-DeWitt technique. New terms in the one-loop corrections were derived and compared with past literature. Additionally, the covariant versions of past results were obtained by extending the ordinary Schwinger-DeWitt approach with Barvinsky and Vilkovisky's method. The one-loop gravitational corrections for a dilaton-extended two-field Starobinsky model were also studied and compared with existing results.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Scott Bassler, Jack Laiho, Marc Schiffer, Judah Unmuth-Yockey
Summary: By studying the emergence of de Sitter space in Euclidean dynamical triangulations (EDT), researchers were able to relate lattice parameters to the partition function of Euclidean quantum gravity. Through simulations, they extracted a value of the renormalized Newton's constant, consistent with previous determinations from scalar particle interactions. The presence of the same universal constant in different sectors of the theory suggests that EDT may offer a viable formulation of quantum gravity.
Article
Astronomy & Astrophysics
Sukanta Panda, Abbas Altafhussain Tinwala, Archit Vidyarthi
Summary: We calculate the tree-level ultraviolet unitarity violation scales for scalar-R2 inflation models by introducing an additional R2|Φ|2 term. Due to specific constraints, we perform the calculations in the Einstein frame and distinguish between metric and Palatini formulations. Following recent works, we debunk the naive predictions for unitarity violations in Higgs' inflation models, and determine how to accurately estimate the behavior of scattering amplitudes in the UV limit.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Michele Arzano, Jerzy Kowalski-Glikman
Article
Astronomy & Astrophysics
Andrzej Borowiec, Lennart Brocki, Jerzy Kowalski-Glikman, Josua Unger
Article
Astronomy & Astrophysics
Michele Arzano, Jerzy Kowalski-Glikman, Wojciech Wislicki
Article
Astronomy & Astrophysics
Remigiusz Durka, Jerzy Kowalski-Glikman
Article
Astronomy & Astrophysics
M. Arzano, L. Brocki, J. Kowalski-Glikman, M. Letizia, J. Unger
Article
Physics, Particles & Fields
Jerzy Kowalski-Glikman, Jerzy Lukierski, Tomasz Trzesniewski
JOURNAL OF HIGH ENERGY PHYSICS
(2020)
Article
Physics, Particles & Fields
Andrzej Borowiec, Lennart Brocki, Jerzy Kowalski-Glikman, Josua Unger
Summary: In this paper, the structure of the algebra of extended BMS symmetries in 3 and 4 spacetime dimensions is discussed, revealing that these algebras contain an infinite number of distinct Poincare subalgebras, a fact previously noted only in the 3 dimensional case. These subalgebras are used to construct an infinite number of different Hopf algebras as quantum deformations of the BMS algebras. Different types of twist-deformations and dual Hopf algebras are also discussed, which could be interpreted as noncommutative, extended quantum spacetimes.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Physics, Particles & Fields
Remigiusz Durka, Jerzy Kowalski-Glikman
Summary: This study investigates the boundary structure of gravity theory formulated as a constrained BF theory, and explores the influence of the cosmological constant and topological terms. The established charges formulas are affected by the presence of the cosmological constant and topological terms. The charges in the AdS-Schwarzschild solution give correct values.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Review
Multidisciplinary Sciences
Michele Arzano, Jerzy Kowalski-Glikman
Summary: This review provides a basic introduction to the kappa-deformed relativistic phase space and free quantum fields, discussing the construction of the kappa-deformed phase space of a classical relativistic particle using Lie bi-algebras and Poisson-Lie groups after reviewing the kappa-Poincare algebra. It also talks about how to construct a free scalar field theory on the non-commutative kappa-Minkowski space associated with kappa-Poincare and demonstrates how the group valued nature of momenta affects field propagation.
Article
Physics, Particles & Fields
Andrzej Borowiec, Jerzy Kowalski-Glikman, Josua Unger
Summary: This paper studies the quantum group deformations of the infinite dimensional symmetry algebra of asymptotically AdS spacetimes in three dimensions, classifies all possible Lie bialgebra structures and explicitly constructs related Hopf algebras. It is found that some incarnations of K-Poincare cannot be extended consistently to infinite dimensional algebras, but certain deformations may have potential physical applications when considering subalgebras.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Physics, Particles & Fields
Remigiusz Durka, Jerzy Kowalski-Glikman
Summary: In this article, we study two BF formulations of gravity, Plebanski theory and MacDowell-Mansouri theory, which both have a negative cosmological constant. While both theories give the standard Einstein equations in the bulk, they differ in the expressions of edge charges. We explicitly compute the asymptotic charges for AdS-Schwarzschild, AdS-Kerr, and AdS-Taub-NUT solutions, and we find that the charges diverge in Plebanski theory but are finite in MacDowell-Mansouri theory. Furthermore, we demonstrate that the MacDowell-Mansouri asymptotic charges, action, and symplectic form are all finite for arbitrary asymptotically AdS spacetimes. Therefore, the MacDowell-Mansouri theory of gravity in asymptotically AdS spaces does not require any counterterms.
JOURNAL OF HIGH ENERGY PHYSICS
(2023)
Article
Astronomy & Astrophysics
Laurent Freidel, Jerzy Kowalski-Glikman, Robert G. Leigh, Djordje Minic
Summary: In this essay, a new understanding of the cosmological constant problem is presented, emphasizing the relationship between vacuum energy and entropy. By introducing a UV-IR regularization and combining it with the holographic bound on entropy, a bound on the cosmological constant consistent with observations is derived. This suggests that the universe is large and the cosmological constant is naturally small due to the presence of a large number of degrees of freedom.
INTERNATIONAL JOURNAL OF MODERN PHYSICS D
(2023)
Article
Astronomy & Astrophysics
Michele Arzano, Jerzy Kowalski-Glikman
Summary: We argue that the concept of identical particles is no longer well defined in quantum systems governed by noncommutative deformations of spacetime symmetries. Such models are characterized by a non-Abelian Lie group in four-momentum space. Our analysis shows that for states containing multiple particles, only the total momentum of the system is a well-defined quantum number, obtained from the non-Abelian composition of individual momenta. We also demonstrate that previous attempts to construct Fock spaces for these models have been unsuccessful due to incorrect assumptions and solve a long-standing problem in the field regarding the covariant nature of momentum quantum numbers under relativistic transformations.
Article
Astronomy & Astrophysics
Jerzy Kowalski-Glikman, Giacomo Rosati
Article
Astronomy & Astrophysics
Laurent Freidel, Jerzy Kowalski-Glikman, Robert G. Leigh, Djordje Minic