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Author |
Borja, E.F.; Diaz-Polo, J.; Garay, I.; Livine, E.R. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Dynamics for a 2-vertex quantum gravity model |
Type |
Journal Article |
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Year |
2010 |
Publication |
Classical and Quantum Gravity |
Abbreviated Journal |
Class. Quantum Gravity |
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Volume |
27 |
Issue ![sorted by Issue field, ascending order (up)](img/sort_asc.gif) |
23 |
Pages |
235010 - 34pp |
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Abstract |
We use the recently introduced U(N) framework for loop quantum gravity to study the dynamics of spin network states on the simplest class of graphs: two vertices linked with an arbitrary number N of edges. Such graphs represent two regions, in and out, separated by a boundary surface. We study the algebraic structure of the Hilbert space of spin networks from the U(N) perspective. In particular, we describe the algebra of operators acting on that space and discuss their relation to the standard holonomy operator of loop quantum gravity. Furthermore, we show that it is possible to make the restriction to the isotropic/homogeneous sector of the model by imposing the invariance under a global U(N) symmetry. We then propose a U(N)-invariant Hamiltonian operator and study the induced dynamics. Finally, we explore the analogies between this model and loop quantum cosmology and sketch some possible generalizations of it. |
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Address |
[Borja, Enrique F.; Garay, Inaki] Univ Erlangen Nurnberg, Inst Theoret Phys 3, D-91058 Erlangen, Germany, Email: etera.livine@ens-lyon.fr |
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Iop Publishing Ltd |
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English |
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0264-9381 |
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ISI:000284211600011 |
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no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ elepoucu @ |
Serial |
341 |
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Permanent link to this record |
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Author |
Alfonso, V.I.; Bejarano, C.; Beltran Jimenez, J.; Olmo, G.J.; Orazi, E. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
The trivial role of torsion in projective invariant theories of gravity with non-minimally coupled matter fields |
Type |
Journal Article |
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Year |
2017 |
Publication |
Classical and Quantum Gravity |
Abbreviated Journal |
Class. Quantum Gravity |
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Volume |
34 |
Issue ![sorted by Issue field, ascending order (up)](img/sort_asc.gif) |
23 |
Pages |
235003 - 20pp |
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Keywords |
modified gravity; metric-affine theories; torsion; non-minimal couplings |
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Abstract |
We study a large family of metric-affine theories with a projective symmetry, including non-minimally coupled matter fields which respect this invariance. The symmetry is straightforwardly realised by imposing that the connection only enters through the symmetric part of the Ricci tensor, even in the matter sector. We leave the connection completely free (including torsion), and obtain its general solution as the Levi-Civita connection of an auxiliary metric, showing that the torsion only appears as a projective mode. This result justifies the widely used condition of setting vanishing torsion in these theories as a simple gauge choice. We apply our results to some particular cases considered in the literature, including the so-called Eddington-inspired-Born-Infeld theories among others. We finally discuss the possibility of imposing a gauge fixing where the connection is metric compatible, and comment on the genuine character of the non-metricity in theories where the two metrics are not conformally related. |
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Address |
[Alfonso, Victor I.] Univ Fed Campina Grande, Unidade Acad Fis, BR-58109970 Campina Grande, PB, Brazil, Email: viafonso@df.ufcg.edu.br; |
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Iop Publishing Ltd |
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0264-9381 |
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WOS:000414726500001 |
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no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
3353 |
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Author |
Araujo Filho, A.A.; Furtado, J.; Reis, J.A.A.S.; Silva, J.E.G. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Thermodynamical properties of an ideal gas in a traversable wormhole |
Type |
Journal Article |
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Year |
2023 |
Publication |
Classical and Quantum Gravity |
Abbreviated Journal |
Class. Quantum Gravity |
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Volume |
40 |
Issue ![sorted by Issue field, ascending order (up)](img/sort_asc.gif) |
24 |
Pages |
245001 - 20pp |
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Keywords |
wormhole; thermodynamic properties; Ellis wormhole |
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Abstract |
In this work, we analyze the thermodynamic properties of non-interacting particles under influence of the gravitational field of a traversable wormhole. In particular, we investigate how the thermodynamic quantities are affected by the Ellis wormhole geometry, considering three different regions to our study: asymptotically far, close to the throat, and at the throat. The thermodynamic quantities turn out to depend strongly on parameter that controls the wormhole throat radius. By varying it, there exist an expressive modification in the thermodynamic state quantities, exhibiting both usual matter and dark energy-like behaviors. Finally, the interactions are regarded to the energy density and it seems to indicate that it “cures” the dark energy-like features. |
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Address |
[Araujo Filho, A. A.] Univ Valencia, Dept Fis Teor, Burjassot 46100, Valencia, Spain, Email: dilto@fisica.ufc.br |
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IOP Publishing Ltd |
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English |
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0264-9381 |
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Notes |
WOS:001098744300001 |
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no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5792 |
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Permanent link to this record |
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Author |
Bazeia, D.; Losano, L.; Olmo, G.J.; Rubiera-Garcia, D. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Geodesically complete BTZ-type solutions of 2+1 Born-Infeld gravity |
Type |
Journal Article |
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Year |
2017 |
Publication |
Classical and Quantum Gravity |
Abbreviated Journal |
Class. Quantum Gravity |
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Volume |
34 |
Issue ![sorted by Issue field, ascending order (up)](img/sort_asc.gif) |
4 |
Pages |
045006 - 21pp |
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Keywords |
Born-Infeld gravity; BTZ; wormholes; nonsingular solutions; geodesic completeness |
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Abstract |
We study Born-Infeld gravity coupled to a static, non-rotating electric field in 2 + 1 dimensions and find exact analytical solutions. Two families of such solutions represent geodesically complete, and hence nonsingular, spacetimes. Another family represents a point-like charge with a singularity at the center. Despite the absence of rotation, these solutions resemble the charged, rotating BTZ solution of general relativity but with a richer structure in terms of horizons. The nonsingular character of the first two families turn out to be attached to the emergence of a wormhole structure on their innermost region. This seems to be a generic prediction of extensions of general relativity formulated in metric-affine (or Palatini) spaces, where metric and connection are regarded as independent degrees of freedom. |
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Address |
[Bazeia, D.; Losano, L.; Olmo, Gonzalo J.] Univ Fed Paraiba, Dept Fis, BR-58051900 Joao Pessoa, Paraiba, Brazil, Email: bazeia@fisica.ufpb.br; |
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Publisher |
Iop Publishing Ltd |
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English |
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ISSN |
0264-9381 |
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Conference |
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Notes |
WOS:000395398800002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
3013 |
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Permanent link to this record |
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Author |
Borja, E.F.; Freidel, L.; Garay, I.; Livine, E.R. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
U(N) tools for loop quantum gravity: the return of the spinor |
Type |
Journal Article |
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Year |
2011 |
Publication |
Classical and Quantum Gravity |
Abbreviated Journal |
Class. Quantum Gravity |
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Volume |
28 |
Issue ![sorted by Issue field, ascending order (up)](img/sort_asc.gif) |
5 |
Pages |
055005 - 28pp |
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Abstract |
We explore the classical setting for the U(N) framework for SU(2) intertwiners for loop quantum gravity and describe the corresponding phase space in terms of spinors with the appropriate constraints. We show how its quantization leads back to the standard Hilbert space of intertwiner states defined as holomorphic functionals. We then explain how to glue these intertwiners states in order to construct spin network states as wavefunctions on the spinor phase space. In particular, we translate the usual loop gravity holonomy observables to our classical framework. Finally, we propose how to derive our phase space structure from an action principle which induces non-trivial dynamics for the spin network states. We conclude by applying explicitly our framework to states living on the simple 2-vertex graph and discuss the properties of the resulting Hamiltonian. |
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Address |
[Borja, Enrique F.; Garay, Inaki] Univ Erlangen Nurnberg, Inst Theoret Phys 3, D-91058 Erlangen, Germany, Email: etera.livine@ens-lyon.fr |
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Publisher |
Iop Publishing Ltd |
Place of Publication |
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English |
Summary Language |
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Series Volume |
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Series Issue |
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ISSN |
0264-9381 |
ISBN |
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Conference |
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Notes |
ISI:000287308700005 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
579 |
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Permanent link to this record |
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Author |
Olmo, G.J.; Rubiera-Garcia, D.; Sanchez-Puente, A. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Accelerated observers and the notion of singular spacetime |
Type |
Journal Article |
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Year |
2018 |
Publication |
Classical and Quantum Gravity |
Abbreviated Journal |
Class. Quantum Gravity |
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Volume |
35 |
Issue ![sorted by Issue field, ascending order (up)](img/sort_asc.gif) |
5 |
Pages |
055010 - 18pp |
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Keywords |
general relativity; geodesic behaviour; black holes; spacetime singularities; modified theories of gravity |
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Abstract |
Geodesic completeness is typically regarded as a basic criterion to determine whether a given spacetime is regular or singular. However, the principle of general covariance does not privilege any family of observers over the others and, therefore, observers with arbitrary motions should be able to provide a complete physical description of the world. This suggests that in a regular spacetime, all physically acceptable observers should have complete paths. In this work we explore this idea by studying the motion of accelerated observers in spherically symmetric spacetimes and illustrate it by considering two geodesically complete black hole spacetimes recently described in the literature. We show that for bound and locally unbound accelerations, the paths of accelerated test particles are complete, providing further support to the regularity of such spacetimes. |
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Address |
[Olmo, Gonzalo J.; Sanchez-Puente, Antonio] Univ Valencia, Dept Fis Teor, CSIC, Ctr Mixto, E-46100 Valencia, Spain, Email: gonzalo.olmo@uv.es; |
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Publisher |
Iop Publishing Ltd |
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English |
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ISSN |
0264-9381 |
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Conference |
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Notes |
WOS:000424042100001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
3473 |
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Permanent link to this record |
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Author |
Fernandez-Silvestre, D.; Foo, J.; Good, M.R.R. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
On the duality of Schwarzschild-de Sitter spacetime and moving mirror |
Type |
Journal Article |
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Year |
2022 |
Publication |
Classical and Quantum Gravity |
Abbreviated Journal |
Class. Quantum Gravity |
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Volume |
39 |
Issue ![sorted by Issue field, ascending order (up)](img/sort_asc.gif) |
5 |
Pages |
055006 - 18pp |
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Keywords |
QFT in curved spacetime; black holes; cosmological horizons; moving mirrors |
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Abstract |
The Schwarzschild-de Sitter (SdS) metric is the simplest spacetime solution in general relativity with both a black hole event horizon and a cosmological event horizon. Since the Schwarzschild metric is the most simple solution of Einstein's equations with spherical symmetry and the de Sitter metric is the most simple solution of Einstein's equations with a positive cosmological constant, the combination in the SdS metric defines an appropriate background geometry for semi-classical investigation of Hawking radiation with respect to past and future horizons. Generally, the black hole temperature is larger than that of the cosmological horizon, so there is heat flow from the smaller black hole horizon to the larger cosmological horizon, despite questions concerning the definition of the relative temperature of the black hole without a measurement by an observer sitting in an asymptotically flat spacetime. Here we investigate the accelerating boundary correspondence of the radiation in SdS spacetime without such a problem. We have solved for the boundary dynamics, energy flux and asymptotic particle spectrum. The distribution of particles is globally non-thermal while asymptotically the radiation reaches equilibrium. |
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Address |
[Fernandez-Silvestre, Diego] Univ Valencia, CSIC, Dept Fis Teor, C Dr Moliner 50, Burjassot 46100, Spain, Email: diefer2@alumni.uv.es; |
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IOP Publishing Ltd |
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English |
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0264-9381 |
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Conference |
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Notes |
WOS:000754064600001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5130 |
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Permanent link to this record |
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Author |
Araujo Filho, A.A.; Hassanabadi, H.; Heidari, N.; Kriz, J.; Zare, S. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Gravitational traces of bumblebee gravity in metric-affine formalism |
Type |
Journal Article |
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Year |
2024 |
Publication |
Classical and Quantum Gravity |
Abbreviated Journal |
Class. Quantum Gravity |
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Volume |
41 |
Issue ![sorted by Issue field, ascending order (up)](img/sort_asc.gif) |
5 |
Pages |
055003 - 21pp |
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Keywords |
bumblebee gravity; metric affine formalism; shadows |
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Abstract |
This work explores various manifestations of bumblebee gravity within the metric-affine formalism. We investigate the impact of the Lorentz violation parameter, denoted as X, on the modification of the Hawking temperature. Our calculations reveal that as X increases, the values of the Hawking temperature attenuate. To examine the behavior of massless scalar perturbations, specifically the quasinormal modes, we employ the Wentzel-Kramers-Brillouin method. The transmission and reflection coefficients are determined through our calculations. The outcomes indicate that a stronger Lorentz-violating parameter results in slower damping oscillations of gravitational waves. To comprehend the influence of the quasinormal spectrum on time-dependent scattering phenomena, we present a detailed analysis of scalar perturbations in the time-domain solution. Additionally, we conduct an investigation on shadows, revealing that larger values of X correspond to larger shadow radii. Furthermore, we constrain the magnitude of the shadow radii using the EHT horizon-scale image of SgrA* . Finally, we calculate both the time delay and the deflection angle. |
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Address |
[Araujo Filho, A. A.] Univ Valencia, CSIC, Dept Fis Teor, Ctr MIxto Univ Valencia, Burjassot 46100, Valencia, Spain, Email: dilto@fisica.ufc.br |
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Publisher |
IOP Publishing Ltd |
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English |
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0264-9381 |
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Conference |
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Notes |
WOS:001152994800001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5925 |
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Permanent link to this record |
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Author |
Lledo, M.A.; Sommovigo, L. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Torsion formulation of gravity |
Type |
Journal Article |
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Year |
2010 |
Publication |
Classical and Quantum Gravity |
Abbreviated Journal |
Class. Quantum Gravity |
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Volume |
27 |
Issue ![sorted by Issue field, ascending order (up)](img/sort_asc.gif) |
6 |
Pages |
065014 - 16pp |
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Keywords |
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Abstract |
We explain precisely what it means to have a connection with torsion as a solution of the Einstein equations. While locally the theory remains the same, the new formulation allows for topologies that would have been excluded in the standard formulation of gravity. In this formulation it is possible to couple arbitrary torsion to gauge fields without breaking the gauge invariance. |
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Address |
[Lledo, M. A.; Sommovigo, L.] Univ Valencia, Dept Fis Teor, E-46100 Valencia, Spain, Email: Maria.Lledo@ific.uv.es |
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Publisher |
Iop Publishing Ltd |
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English |
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0264-9381 |
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Conference |
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Notes |
ISI:000275120600015 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ elepoucu @ |
Serial |
498 |
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Permanent link to this record |
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Author |
Navarro-Salas, J. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Black holes, conformal symmetry, and fundamental fields |
Type |
Journal Article |
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Year |
2024 |
Publication |
Classical and Quantum Gravity |
Abbreviated Journal |
Class. Quantum Gravity |
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Volume |
41 |
Issue ![sorted by Issue field, ascending order (up)](img/sort_asc.gif) |
8 |
Pages |
085003 - 14pp |
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Keywords |
black holes; horizons; singularities; conformal symmetry; quantum fields; Standard Model |
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Abstract |
Cosmic censorship protects the outside world from black hole singularities and paves the way for assigning entropy to gravity at the event horizons. We point out a tension between cosmic censorship and the quantum backreacted geometry of Schwarzschild black holes, induced by vacuum polarization and driven by the conformal anomaly. A similar tension appears for the Weyl curvature hypothesis at the Big Bang singularity. We argue that the requirement of exact conformal symmetry resolves both conflicts and has major implications for constraining the set of fundamental constituents of the Standard Model. |
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Address |
[Navarro-Salas, Jose] Univ Valencia, Dept Fis Teor, IFIC, CSIC, E-46100 Burjassot, Valencia, Spain, Email: jnavarro@ific.uv.es |
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IOP Publishing Ltd |
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English |
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0264-9381 |
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Expedition |
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Conference |
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Notes |
WOS:001187435100001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
6029 |
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Permanent link to this record |