Fri - 12/13/24

**Title:

      Hilbert space formalisms for group field theory**  - **Authors:** Steffen Gielen  - **Subjects:** Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)  - **Arxiv link:** [https://arxiv.org/abs/](https://arxiv.org/abs/)  - **Abstract**  Group field theory is a background-independent approach to quantum gravity whose starting point is the definition of a quantum field theory on an auxiliary group manifold (not interpreted as spacetime). Group field theory models can be seen as an extension of matrix and tensor models by additional data, and are traditionally defined through a functional integral whose perturbative expansion generates a sum over discrete geometries. More recently, some efforts have been directed towards formulations of group field theory based on a Hilbert space and operators, in particular in applications to cosmology. This is an attempt to review some of these formulations and their main ideas, to disentangle these constructions as much as possible from applications and phenomenology, and to put them into a wider context of quantum gravity research.

There is no new related paper today

  1. [] - Title: Principles for a Distinguished Global Vacuum: Entropy and the Vacuum State in Causal Set Theory - Joshua Y. L. Jones

Thu - 12/12/24

There is no new related paper today

There is no new related paper today

  1. [] - Title: Non-Vacuum Solutions in Cotton Theory - Serkan Doruk Hazinedar, Yaghoub Heydarzade, Maryam Ranjbar

Wed - 12/11/24

**Title:

      Lecture Notes in Loop Quantum Gravity. LN2: Cauchy problems and pre-quantum states**  - **Authors:** S.Coriasco, L.Fatibene, S.Garruto, A.Orizzonte  - **Subjects:** Subjects: General Relativity and Quantum Cosmology (gr-qc)  - **Arxiv link:** [https://arxiv.org/abs/](https://arxiv.org/abs/)  - **Abstract**  We discuss the structure of covariant equations, relating analytical properties of solutions to algebraic properties of the corresponding differential operator, specifically of its principal symbol. The principal symbol and its globality is discussed for a general quasi-linear PDE system, regardless the algebraic structure the configuration space can have. We also discuss how the typical relativistic model can be under-determined and over-determined at the same time as well as how one can define out of it a well-posed Cauchy problem. This issue leads us to pre-quantum configurations and Cauchy bubbles as the way to set up evolution problems in a compact region of spacetime, taking into account that relativistic models are defined on bare manifolds. The typical application we shall sketch is standard GR.

There is no new related paper today

  1. [] - Title: Semiclassical world is one of infinite many cloneworlds in common spacetime - Lajos Diósi

Tue - 12/10/24

**Title:

      Hamiltonian Theory: generalizations to higher dimensions, supersymmetry and modified gravity**  - **Authors:** Norbert Bodendorfer, Konstantin Eder, Xiangdong Zhang  - **Subjects:** Subjects: General Relativity and Quantum Cosmology (gr-qc)  - **Arxiv link:** [https://arxiv.org/abs/](https://arxiv.org/abs/)  - **Abstract**  Loop quantum gravity in its Hamiltonian form relies on a connection formulation of the gravitational phase space with three key properties: 1.) a compact gauge group, 2.) real variables, and 3.) canonical Poisson brackets. In conjunction, these properties allow to construct a well defined kinematical quantization of the holonomy flux-algebra on top of which the remaining constraints can be implemented. While this idea has traditionally been mainly used for Einstein gravity, any gravitational theory with the above properties can be accommodated. In this paper, we are going to review three strands of work building on this observation, namely the study of higher-dimensional loop quantum gravity, supersymmetric extensions of loop quantum gravity, as well as the quantization of modified gravitational theories.

There is no new related paper today

Mon - 12/09/24

**Title:

      Gravitational quantum speed limit**  - **Authors:** Nicola Pranzini, Lorenzo Maccone  - **Subjects:** Subjects: General Relativity and Quantum Cosmology (gr-qc); Quantum Physics (quant-ph)  - **Arxiv link:** [https://arxiv.org/abs/](https://arxiv.org/abs/)  - **Abstract**  While playing an important role in the foundations of quantum theory, Quantum Speed Limits (QSL) have no role in discussions about the search for quantum gravity. We fill this gap by analysing what QSL arises when superposing spherically symmetric masses in canonical quantum gravity. By this procedure, we find that the quantum mechanical Mandelstam-Tamm and Margolus-Levitin bounds can be improved by superposing a spherically symmetric, static and asymptotically flat spacetime between states with different ADM energies and mass densities. We discuss the feasibility and significance of measuring times via these superpositions.

There is no new related paper today

New papers last week