Fri - 05/12/23

Quantum gravity in the triangular gauge

  • Authors: Thomas Thiemann
  • Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Lattice (hep-lat); High Energy Physics - Theory (hep-th)
  • Arxiv link: https://arxiv.org/abs/2305.06724
  • Abstract Vielbeins are necessary when coupling General Relativity (GR) to fermionic matter. This enhances the gauge group of GR to include local Lorentz transformations. In view of a reduced phase space formulation of quantum gravity, in this work we completely gauge fix that Lorentz gauge symmetry by using a so-called triangular gauge. Having solved the Gauss constraints already classically opens access to new Hilbert space representations which are free of the complications that otherwise arise due to a non Abelian gauge symmetry. In that sense, a connection formulation as being pursued in Loop Quantum Gravity is no longer the only practicable option and other less dimension dependent representations e.g. based on triads and even metrics suggest themselves. These formulations make it easier to identify states representing non-degenerate quantum geometries and thus to investigate the hypersurface deformation algebra which implicitly assumes non-degeneracy.

Worldline path integrals for the graviton

  • Authors: Fiorenzo Bastianelli, Mattia Damia Paciarini
  • Subjects: High Energy Physics - Theory (hep-th)
  • Arxiv link: https://arxiv.org/abs/2305.06650
  • Abstract We present an extension to arbitrary dimensions of the worldline path integral approach to one-loop quantum gravity, which was previously formulated in four spacetime dimensions. By utilizing this method, we recalculate gauge invariant coefficients in arbitrary dimensions. These coefficients were previously obtained through two alternative techniques: the quantization of a ${\cal N}=4$ spinning particle that consistently propagates the graviton on Einstein spaces and the more conventional heat kernel approach. Our worldline path integrals are closer to the latter as they are employed to compute efficiently the trace of the heat kernel. We discuss how the worldline sigma models that reproduce the gauge-fixed graviton and ghosts can be treated in different but equivalent ways.

There is no new related paper today

  1. [2305.06504] - Effect of the cosmological model on LIV constraints from GRB Time-Delays datasets - Denitsa Staicova

  2. [2305.06834] - Black hole entropy contributions from Euclidean cores - Jens Boos

  3. [2305.06552] - Bulk-Boundary Thermodynamics of Charged Black Holes in Higher Derivative Theory - Gurmeet Singh Punia

Thu - 05/11/23

There is no new related paper today

There is no new related paper today

  1. [2305.06046] - Towards a unitary formulation of quantum field theory in curved spacetime I: the case of de Sitter spacetime - K. Sravan Kumar, João Marto

  2. [2305.06136] - QFT with Tensorial and Local Degrees of Freedom: Phase Structure from Functional Renormalization - Joseph Ben Geloun, Andreas G.A. Pithis, Johannes Thürigen

Wed - 05/10/23

Closer look at cosmological consequences of interacting group field theory

  • Authors: Maxime De Sousa, Aurélien Barrau, Killian Martineau
  • Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph)
  • Arxiv link: https://arxiv.org/abs/2305.05438
  • Abstract Group field theory has shown to be a promising framework to derive cosmological predictions from full quantum gravity. In this brief note, we revisit the background dynamics when interaction terms are taken into account and conclude that, although the bounce is clearly robust, providing a geometrical explanation for inflation seems to be very difficult. We consider possible improvements and modifications of the original scenario and derive several limits on the parameters of the model.

There is no new related paper today

  1. [2305.04952] - Geometric Quantum Discord Signals Non-Factorization - Souvik Banerjee, Pablo Basteiro, Rathindra Nath Das, Moritz Dorband

Tue - 05/09/23

Investigating Loop Quantum Gravity Through Strong Gravitational Lensing Effects by Rotating Black Hole and EHT Observations

  • Authors: Jitendra Kumar, Shafqat Ul Islam, Sushant G. Ghosh
  • Subjects: General Relativity and Quantum Cosmology (gr-qc); Astrophysics of Galaxies (astro-ph.GA)
  • Arxiv link: https://arxiv.org/abs/2305.04336
  • Abstract We investigate gravitational lensing in the strong deflection regime by loop quantum gravity (LQG)-motivated rotating black hole (LMRBH) metrics with an additional parameter $l$ besides mass $M$ and rotation $a$. The LMRBH spacetimes are regular everywhere, asymptotically encompassing the Kerr black hole as a particular case and, depending on the parameters, describe black holes with one horizon only (BH-I), black holes with an event horizon and a Cauchy horizon (BH-II), black holes with three horizons (BH-III), or black holes with no horizons (NH) spacetime. It turns out that as the LQG parameter $l$ increases, the unstable photon orbit radius $x_{ps}$, the critical impact parameter $u_{ps}$, the deflection angle $\alpha_D(\theta)$ and angular position $\theta_{\infty}$ also increases. Meanwhile, the angular separation $s$ decreases, and relative magnitude $r_{mag}$ increases with increasing $l$ for prograde motion but they show opposite behaviour for the retrograde motion. For Sgr A, the angular position $\theta_{\infty}$ is $\in$ (16.404, 39.8044) $\mu$as, while for M87 $\in$ (12.3246, 29.9057) $\mu$as. The angular separation $s$ is ranging $\in$ (0.008306-0.37573) $\mu$as for Sgr A* and $\in$ (0.00624-0.282295) $\mu$as for M87. The relative magnitude $r_{mag}$ $\in$ (0.04724, 1.53831). We estimate the time delay between the first and second relativistic images using twenty supermassive galactic centre black holes as lenses. Our analysis concludes that, within the $1 \sigma$ region, a significant portion of the BH-I and BH-II and for a small portion of BH-III parameter space agrees with the EHT results of M87 and Sgr A* whereas NH is completely ruled out. We discover that the EHT results of Sgr A* place more stringent limits on the parameter space of LMRBH black holes than those established by the EHT results of M87*.

There is no new related paper today

  1. [2305.04776] - Electrically charged regular black holes in nonlinear electrodynamics: light rings, shadows and gravitational lensing - Marco A. A. de Paula, Haroldo C. D. Lima Junior, Pedro V. P. Cunha, Luís C. B. Crispino

  2. [2305.04829] - Ideal Gas Thermodynamics with an Invariant Energy Scale - Sudipta Das

  3. [2305.04355] - A bulk manifestation of Krylov complexity - E. Rabinovici, A. Sánchez-Garrido, R. Shir, J. Sonner

  4. [2305.04437] - Phase Diagram of the Two-Flavor Schwinger Model at Zero Temperature - Ross Dempsey, Igor R. Klebanov, Silviu S. Pufu, Benjamin T. Søgaard, Bernardo Zan

Mon - 05/08/23

There is no new related paper today

There is no new related paper today

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