Fri - 07/14/23

Primordial Power Spectrum in Modified Cosmology: From Thermodynamics of Spacetime to Loop Quantum Cosmology

  • Authors: Ana Alonso-Serrano, Guillermo A. Mena Marugan, Antonio Vicente-Becerril
  • Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)
  • Arxiv link: https://arxiv.org/abs/2307.06813
  • Abstract We investigate the implications for cosmology of a phenomenological quantum gravity approach based on thermodynamics. We analyze in detail the corresponding primordial power spectrum. The considered modified cosmological scenario has similarities with Loop Quantum Cosmology. Actually, one recovers the same effective background dynamics by fixing the value of the free parameter of the modified approach. In particular, the background experiences a bounce that solves the initial singularity. Adopting background-dependent equations for the primordial perturbations like those derived in General Relativity, the studied model can be considered a generalization of the dressed metric formalism in Loop Quantum Cosmology. We focus our discussion on the spectrum of tensor perturbations. For these perturbations, we compute the exact form of the background-dependent effective mass that affects their propagation. Since there are background regimes in the modified cosmology that are far away from slow-roll inflation, we do not have at our disposal a privileged vacuum like the Bunch-Davies state. We then select the state of the perturbations by a recently proposed criterion that removes unwanted oscillations in the power spectrum. Finally, we numerically compute the spectrum of this vacuum and compare it with other spectra obtained in the literature, especially with one corresponding to an alternative quantization prescription in Loop Quantum Cosmology (called the hybrid prescription).

There is no new related paper today

  1. [2307.06415] - The Photon Sphere and the AdS/CFT Correspondence - Marcos Riojas, Hao-Yu Sun

  2. [2307.06531] - SVD Entanglement Entropy - Arthur J. Parzygnat, Tadashi Takayanagi, Yusuke Taki, Zixia Wei

Thu - 07/13/23

Geometric parametrization of $SO(D+1)$ phase space of all dimensional loop quantum gravity: II. Beyond the simplicity constraint surface

  • Authors: Gaoping Long
  • Subjects: General Relativity and Quantum Cosmology (gr-qc)
  • Arxiv link: https://arxiv.org/abs/2307.05542
  • Abstract The regularization of the scalar constraint and the Fermion coupling problem indicate that it is necessary to consider some kind of gauge fixing methods to deal with the simplicity constraint in all dimensional $SO(D+1)$ loop quantum gravity. The coherent state with well-behaved peakedness property is an essential ingredient to carry out the gauge fixing method. To provide the basic tool for constructing such kind of coherent state, we generalize the twisted geometry parametrization of the $SO(D+1)$ phase space of $(1+D)$-dimensional loop quantum gravity from the edge simplicity constraint surface to a dense subspace in the $SO(D+1)$ phase space. The symplectic structure on the twisted geometric parameter space and the Poisson structure in terms of the twisted geometric variables are analyzed. Besides, we discuss the relation between the twisted geometry parametrizations constructed on the edge simplicity constraint surface and the larger dense subspace of the $SO(D+1)$ phase space, and our result show that these two type of parametrizations are equivalent to each other by carrying out the gauge reduction with respect to the edge simplicity constraint.

There is no new related paper today

  1. [2307.05554] - Schrödinger and Klein-Gordon theories of black holes from the quantization of the Oppenheimer and Snyder gravitational collapse - Christian Corda

  2. [2307.06068] - On the renormalization of non-polynomial field theories - Andrea Santonocito, Dario Zappala

  3. [2307.06164] - A Fermi Model of Quantum Black Hole - Chong-Sun Chu, Rong-Xin Miao

Wed - 07/12/23

There is no new related paper today

There is no new related paper today

  1. [2307.05032] - Microscopic Entanglement Wedges - Robert de Mello Koch

Tue - 07/11/23

One-Loop Quantum Effects in Carroll Scalars

  • Authors: Kinjal Banerjee, Rudranil Basu, Bhagya Krishnan, Sabyasachi Maulik, Aditya Mehra, Augniva Ray
  • Subjects: High Energy Physics - Theory (hep-th)
  • Arxiv link: https://arxiv.org/abs/2307.03901
  • Abstract Carrollian field theories at the classical level possess infinite number of space-time symmetries, namely the supertranslations. In this article we enquire whether these symmetries for interacting Carrollian scalar field theory survive in presence of quantum effects. For interactions polynomial in the field, the answer is in the affirmative. We also studied a renormalization group flow particularly tailored to respect the manifest Carroll invariance and analyzed the consequences of introducing Carroll-breaking deformations. The renormalization group flow, with perturbative loop level effects taken into account, indicates a new fixed point apart from the Gaussian ones.

There is no new related paper today

  1. [2307.04150] - On Horizon Molecules and Entropy in Causal Sets - Djamel Dou

  2. [2307.03830] - 3d Quantum Gravity Partition Function at 3 Loops: a brute force computation - Mauricio Leston, Andrés Goya, Guillem Pérez Nadal, Mario Passaglia, Gaston Giribet

  3. [2307.04491] - Thermal Corrections to Rényi Entropy in BMS Field Theory - Yuan Zhong

Mon - 07/10/23

There is no new related paper today

There is no new related paper today

  1. [2307.03520] - Constraining Snyder and GUP models with low-mass stars - Anna Pachoł, Aneta Wojnar

  2. [2307.03707] - AdS$_3$/RMT$_2$ Duality - Gabriele Di Ubaldo, Eric Perlmutter

New papers last week