Fri - 06/30/23

There is no new related paper today

There is no new related paper today

  1. [2306.16426] - Entropy as logarithmic term of the central charge and modified Friedmann equation in AdS/CFT correspondence - M. Bousder, E. Salmani, H. Ez-Zahraouy

  2. [2306.16952] - The Hawking effect in the particles-partners correlations - Roberto Balbinot, Alessandro Fabbri

  3. [2306.16450] - Entropy Bounds and the Species Scale Distance Conjecture - José Calderón-Infante, Alberto Castellano, Alvaro Herráez, Luis E. Ibáñez

Thu - 06/29/23

There is no new related paper today

There is no new related paper today

Wed - 06/28/23

Observations in Quantum Cosmology

  • Authors: Leonardo Chataignier, Claus Kiefer, Paulo Moniz
  • Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th); Quantum Physics (quant-ph)
  • Arxiv link: https://arxiv.org/abs/2306.14948
  • Abstract In this review, we focus on whether a canonical quantization of general relativity can produce testable predictions for cosmology. In particular, we examine how this approach can be used to model the evolution of primordial perturbations. This program of quantum geometrodynamics, first advocated by John Wheeler and Bryce DeWitt, has a straightforward classical limit, and it describes the quantum dynamics of all fields, gravitational and matter. In this context, in which a classical background metric is absent, it is necessary to discuss what constitutes an observation. We first address this issue in the classical theory and then turn to the quantum theory. We argue that predictions are relational, that is, relative to physical clocks and rods, and that they can be straightforwardly obtained in a perturbative approach with respect to Newton’s constant, which serves as a coupling parameter. This weak-coupling expansion leads to a perturbative Hilbert space for quantum cosmology, and to corrections to the dynamics of quantum fields on a classical, fixed background metric. These corrections imply modifications of primordial power spectra, which may lead to signatures in the anisotropy spectrum of the Cosmic Microwave Background (CMB) radiation, for which we discuss concrete results. We conclude that the subject of quantum geometrodynamics, the oldest and most conservative approach to canonical quantum gravity, not only illuminates conceptual issues in quantum gravitation, but may also lead to observational prospects in cosmology and elsewhere.

Holographic realization from inflation to reheating in generalized entropic cosmology

  • Authors: Sergei D. Odintsov, Simone D’Onofrio, Tanmoy Paul
  • Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)
  • Arxiv link: https://arxiv.org/abs/2306.15225
  • Abstract The growing cosmological interest of different entropy functions (like the Tsallis entropy, the R'{e}nyi entropy, the Barrow entropy, the Sharma-Mittal entropy, the Kaniadakis entropy and the Loop Quantum gravity entropy) naturally raises an important question: “Does there exist a generalized entropy that can bring all the known entropies proposed so far within a single umbrella?” In spirit of this, recently a four parameter generalized entropy has been formulated that reduces to different known entropies for suitable limits of the parameters. Based on such four parameter generalized entropy (symbolized by $S_\mathrm{g}$), in the present paper, we examine the universe’s evolution during its early phase, particularly from inflation to reheating, in the context of entropic cosmology where the entropic energy density acts as the inflaton. It turns out that the entropic energy successfully drives an early inflationary phase with a graceful exit, and moreover, the theoretical expectations of the observable indices get consistent with the recent Planck data for suitable ranges of the entropic parameters. After the inflation ends, the universe enters to a reheating stage when the entropic energy decays to relativistic particles with a certain decay rate. Actually the presence of the entropic parameters in the $S_\mathrm{g}$ ensures a continuous evolution of the Hubble parameter from a quasi de-Sitter phase during the inflation to a power law phase during the reheating stage dominated by a constant EoS parameter. Consequently we investigate the reheating phenomenology, and scan the entropic parameters from both the inflation and reheating requirements. We further address the possibility of instantaneous reheating in the present context of generalized entropy.

There is no new related paper today

  1. [2306.15484] - Finiteness of quantum gravity with matter on a PL spacetime - Aleksandar Mikovic

Tue - 06/27/23

There is no new related paper today

Perturbative BF theory in axial, Anosov, gauge

  • Authors: Michele Schiavina, Thomas Stucker
  • Subjects: Mathematical Physics (math-ph); Dynamical Systems (math.DS)
  • Arxiv link: https://arxiv.org/abs/2306.14681
  • Abstract The twisted Ruelle zeta function of a contact, Anosov vector field is shown to be equal, as a meromorphic function of the complex parameter $\hbar\in\mathbb{C}$ and up to a phase, to the partition function of an $\hbar$-linear quadratic perturbation of $BF$ theory, using an “axial” gauge fixing condition given by the Anosov vector field. Equivalently, it is also obtained as the expectation value of the same quadratic, $\hbar$-linear, perturbation, within a perturbative quantisation scheme for $BF$ theory, suitably generalised to work when propagators have distributional kernels.

  1. [2306.13782] - Quantum Curvature as Key to the Quantum Universe - R. Loll

  2. [2306.14643] - Universal scaling dimensions for highly irrelevant operators in the Local Potential Approximation - Vlad-Mihai Mandric, Tim R. Morris, Dalius Stulga

  3. [2306.14823] - Critical JT Gravity - Alicia Castro

Mon - 06/26/23

There is no new related paper today

There is no new related paper today

  1. [2306.13143] - Bubbles of cosmology in AdS/CFT - Abhisek Sahu, Petar Simidzija, Mark Van Raamsdonk

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