Loop quantum gravity and light propagation

Alfaro, Jorge; Morales‐Técotl, H. A.; Urrutia, L. F.

doi:10.1103/physrevd.65.103509

Cited by 305 publications

(279 citation statements)

References 70 publications

(92 reference statements)

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“…[10] for a simply connected, nonstatic spacetime made-up of many S 2 × S 2 "gravitational bubbles." More drastic changes in the photon dispersion law have, for example, been found in certain loop quantum gravity calculations [26,27]. Compared to these calculations (which have the Planck length as the fundamental scale), ours is relatively straightforward, the only prerequisite being a multiply connected topology which is then probed by the chiral fermions of the Standard Model; see Sec.…”

Section: B Photon Modelmentioning

confidence: 99%

Spacetime foam,CPTanomaly, and photon propagation

2004

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The CPT anomaly of certain chiral gauge theories has been established previously for flat multiply connected spacetime manifolds M of the type R 3 × S 1 , where the noncontractible loops have a minimal length. In this article, we show that the CPT anomaly also occurs for manifolds where the noncontractible loops can be arbitrarily small. Our basic calculation is performed for a flat noncompact manifold with a single "puncture," namely M = R 2 × (R 2 \ {0}). A hypothetical spacetime foam might have many such punctures (or other structures with similar effects). Assuming the multiply connected structure of the foam to be time independent, we present a simple model for photon propagation, which generalizes the single-puncture result. This model leads to a modified dispersion law of the photon. Observations of high-energy photons (gamma-rays) from explosive extragalactic events can then be used to place an upper bound on the typical length scale of these punctures.

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Section: B Photon Modelmentioning

confidence: 99%

Spacetime foam,CPTanomaly, and photon propagation

2004

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“…And the propagation of light through the space-time with the foamy structure would show a non-trivial dispersion relation in vacuum (Amelino-Camelia et al 1998), which could leads to the violation of Lorentz invariance. Constraining the Lorentz invariance violation (LIV) effect has been thought as an effective method to test the accuracy of QG theories, such as loop quantum gravity (Gambini & Pullin 1999;Alfaro et al 2002), string theory (Kostelecký & Samuel 1989), double special relativity (Amelino-Camelia & Ahluwalia 2002), and so on. Since it is generally expected for QG to manifest itself fully at the Planck scale, the Planck energy scale (E QG ≈ E Pl = c 5 /G ≃ 1.22 × 10 19 ) being a natural one at which Lorentz invariance is predicted to be broken (see, e.g., Amelino-Camelia 2013, and references therein).…”

Section: Constraining Lorentz Invariance Violationmentioning

confidence: 99%

GRBs and Fundamental Physics

Petitjean

Wang

et al. 2016

Space Sci Rev

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Gamma-ray bursts (GRBs) are short and intense flashes at the cosmological distances, which are the most luminous explosions in the Universe. The high luminosities of GRBs make them detectable out to the edge of the visible universe. So, they are unique tools to probe the properties of high-redshift universe: including the cosmic expansion and dark energy, star formation rate, the reionization epoch and the metal evolution of the Universe. First, they can be used to constrain the history of cosmic acceleration and the evolution of dark energy in a redshift range hardly achievable by other cosmological probes. Second, long GRBs are believed to be formed by collapse of massive stars. So they can be used to derive the high-redshift star formation rate, which can not be probed by current observations. Moreover, the use of GRBs as cosmological tools could unveil the reionization history and metal evolution of the Universe, the intergalactic medium (IGM) properties and the nature of first stars in the early universe. But beyond that, the GRB high-energy photons can be applied to constrain Lorentz invariance violation (LIV) and to test Einstein's Equivalence Principle (EEP). In this paper, we review the progress on the GRB cosmology and fundamental physics probed by GRBs.

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“…It is to say, particles with different energies have different energy-momentum relations. In addition, it should be pointed out, MDR can be presented by different ways [34][35][36] and can be used to explain a rich and energetic phenomenology [29][30][31][32].…”

Section: The Modified Black Holes From the Gravity's Rainbowmentioning

confidence: 99%

Hawking radiation and black hole entropy in a gravity’s rainbow

Liu

Zhu

2008

Gen Relativ Gravit

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In the context of gravity's rainbow, Planck scale correction on Hawking radiation and black hole entropy in Parikh and Wilczk's tunneling framework is studied. We calculate the tunneling probability of massless particles in the modified Schwarzschild black holes from gravity's rainbow. In the tunneling process, when a particle gets across the horizon, the metric fluctuation must be taken into account, not only due to energy conservation but also to spacetime Planck scale effect. Our results show that the emission rate is related to changes of the black hole's quantum corrected entropies before and after the emission. In the same time, for the modified black holes, a series of correction terms including a logarithmic term to Bekenstein-Hawking entropy are obtained. Correspondingly, the spectrum of Planck scale corrected emission is obtained and it deviates from the thermal spectrum. In addition, a specific form of modified dispersion relation is proposed and applied.

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Loop quantum gravity and light propagation

Abstract: Within loop quantum gravity we construct a coarse-grained approximation for the Einstein-Maxwell theory that yields effective Maxwell equations in flat spacetime comprising Planck scale corrections.

Cited by 305 publications

References 70 publications

Spacetime foam,CPTanomaly, and photon propagation

Spacetime foam,CPTanomaly, and photon propagation

GRBs and Fundamental Physics

Hawking radiation and black hole entropy in a gravity’s rainbow

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