Fri - 12/17/21

Fermion coupling to loop quantum gravity: canonical formulation

  • Authors: Jerzy Lewandowski, Cong Zhang
  • Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)
  • Arxiv link: https://arxiv.org/abs/2112.08865
  • Abstract In the model of fermion field coupled to loop quantum gravity, we consider the Gauss and the Hamiltonian constraints. According to the explicit solutions to the Gauss constraint, the fermion spins and the gravitational spin networks intertwine with each other so that the fermion spins contribute to the volume of the spin network vertices. For the Hamiltonian constraint, the regularization and quantization procedures are presented in detail. By introducing an adapted vertex Hilbert space to remove the regulator, we propose a diffeomorphism covariant graph-changing Hamiltonian constraint operator. This operator shows how fermions move in the loop quantum gravity spacetime and simultaneously influences the background quantum geometry.

Comparison of the Semiclassical and Quantum Dynamics of the Bianchi I Cosmology in the Polymer and GUP Extended Paradigms

  • Authors: Gabriele Barca, Eleonora Giovannetti, Giovanni Montani
  • Subjects: General Relativity and Quantum Cosmology (gr-qc)
  • Arxiv link: https://arxiv.org/abs/2112.08905
  • Abstract We compare in some detail Polymer Quantum Mechanics and the Generalized Uncertainty Principle approach to clarify to what extent we can treat them on the same footing. We show that, while on a semiclassical level they may be formulated as similar modifications of the Poisson algebra, on a quantum level they intrinsically differ because PQM implies no absolute minimal uncertainty on position. Then we implement these schemes to Bianchi I cosmology on a semiclassical level deforming only the algebra of the Universe volume, searching for alternative formulations able to account for the modified Friedmann equations emerging in Brane Cosmology and Loop Quantum Cosmology. On a pure quantum level, we implement the two approaches through their original setups and reduce the two resulting Wheeler-DeWitt equations to the same morphological structure, showing how the polymer formalism is associated with a bouncing dynamics while in the Generalized Uncertainty Principle case the singularity is still present. The implications of the wavepacket spreading are also discussed in both approaches, outlining that, when the singularity survives, the Planckian era must necessarily be approached by a fully quantum (non-peaked) state of the Universe.

Studying the EPRL spinfoam self-energy

  • Authors: Pietropaolo Frisoni
  • Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th); Computational Physics (physics.comp-ph)
  • Arxiv link: https://arxiv.org/abs/2112.08528
  • Abstract I present some recent progresses in the study of the EPRL self-energy amplitude. New numerical methods allow to analyze how the divergence scales, for which previous works provided very different lower and upper bounds. I discuss the role that the Immirzi parameter plays in the asymptotic behavior, and the dependence of the scaling on some boundary data. Finally, I discuss the dynamical expectation values of some relevant geometric boundary observables.

  1. [2112.08531] - Four Attitudes Towards Singularities in the Search for a Theory of Quantum Gravity - Karen Crowther, Sebastian De Haro

  2. [2112.08383] - Taming the Landscape of Effective Theories - Thomas W. Grimm

  3. [2112.08422] - Holographic approach to compact stars and their binary mergers - Carlos Hoyos, Niko Jokela, Aleksi Vuorinen

  4. [2112.08715] - Flavored ABJM theory on the sphere and holographic F-functions - Niko Jokela, Jani Kastikainen, Elias Kiritsis, Francesco Nitti

  5. [2112.09122] - Reflected entropy in random tensor networks - Chris Akers, Thomas Faulkner, Simon Lin, Pratik Rath

Thu - 12/16/21

Consequences of regularization ambiguities in Loop Quantum Cosmology

  • Authors: Maciej Kowalczyk
  • Subjects: General Relativity and Quantum Cosmology (gr-qc)
  • Arxiv link: https://arxiv.org/abs/2112.07786
  • Abstract Ambiguities of the so-called Thiemann regularization in Loop Quantum Cosmology lead to freedom in how to construct a particular quantization prescription. So far three distinct examples of such have been proposed in the literature. For two of them, detailed analysis has been already performed in the literature. In this thesis, the methodology developed for these is applied to study in detail the third one, which will be referred to as mLQC-II. In particular, the mathematical properties of the operator of the quantum version of full Hamiltonian constraint are examined. These properties indicate that the evolution of the system is uniquely determined. Furthermore, an investigation of dynamics is performed by finding the expectation value of the volume as a function of the scalar field and constants of motion. This result is next compared to the trajectories predicted with the so-called effective dynamics. Finally, the main properties of studied prescription are compared against those of other (already investigated) ones.

Black Holes, Gravitational Waves and Quantum Gravity

  • Authors: W. F. Chagas-Filho
  • Subjects: General Relativity and Quantum Cosmology (gr-qc)
  • Arxiv link: https://arxiv.org/abs/2112.08019
  • Abstract Loop Quantum Gravity is a theory that attempts to describe the quantum mechanics of the gravitational field based on the canonical quantization of General Relativity. According to Loop Quantum Gravity, in a gravitational field, geometric quantities such as area and volume are quantized in terms of the Planck lenth. In this paper we present the basic ideas for a future, mathematically more rigorous, attempt to combine black holes and gravitational waves using the quantization of geometric quantities introduced by Loop Quantum Gravity.

Lattice BF Theory, Dumbbells, and Composite Fermions

  • Authors: Tom Banks, Bingnan Zhang
  • Subjects: High Energy Physics - Theory (hep-th); Strongly Correlated Electrons (cond-mat.str-el); High Energy Physics - Lattice (hep-lat)
  • Arxiv link: https://arxiv.org/abs/2112.08316
  • Abstract We formulate $U(1)$ $bda$ Chern-Simons theory, which is also called BF theory, on a lattice, adapting a method proposed by Kantor and Susskind for the groups $\mathbb{R}$ and $\mathbb{Z}_N$. Our method applies to any finite or infinite abelian group. We study the discrete symmetries and use the model to provide a rigorous treatment of the composite fermion theory of the fractional quantum Hall effect (FQHE), with no ambiguities relating to intersecting Wilson/’t Hooft lines. We derive Jain’s fractions, and one can also calculate corrections to the mean field solution within this framework. We also generalize the formalism to higher form gauge models in arbitrary dimension, and suggest a possible non-Abelian extension.

  1. [2112.07678] - Open-Closed Correspondence of K-theory and Cobordism - Ralph Blumenhagen, Niccolò Cribiori

  2. [2112.07682] - Elliptic K3 Surfaces at Infinite Complex Structure and their Refined Kulikov models - Seung-Joo Lee, Timo Weigand

Wed - 12/15/21

There is no new related paper today

There is no new related paper today

  1. [2112.06956] - Nonperturbative Negative Geometries: Amplitudes at Strong Coupling and the Amplituhedron - Nima Arkani-Hamed, Johannes Henn, Jaroslav Trnka

Tue - 12/14/21

There is no new related paper today

There is no new related paper today

  1. [2112.05788] - Time in quantum cosmology - Claus Kiefer, Patrick Peter

  2. [2112.06446] - Gravitational wave constraints on Lorentz and parity violations in gravity: high-order spatial derivative cases - Cheng Gong, Tao Zhu, Rui Niu, Qiang Wu, Jing-Lei Cui, Xin Zhang, Wen Zhao, Anzhong Wang

  3. [2112.06758] - Quantum Mechanics on the curved contangent bundle – a naïve view - Fabian Wagner

  4. [2112.06894] - Quantum decoherence of the homogeneous modes during inflation - Oleg O. Novikov, Arina M. Shtennikova

  5. [2112.06237] - Emergent dual holographic description as a non-perturbative generalization of the Wilsonian renormalization group - Ki-Seok Kim, Shinsei Ryu, Kanghoon Lee

  6. [2112.06314] - Effective quantum gravity, cosmological constant and the Standard Model of particle physics - Breno L. Giacchini, Tibério de Paula Netto, Ilya L. Shapiro

Mon - 12/13/21

There is no new related paper today

There is no new related paper today

New papers last week