Ambiguity of black hole entropy in loop quantum gravity

Tamaki, Takashi; Nomura, Hidefumi

doi:10.1103/physrevd.72.107501

Cited by 15 publications

(18 citation statements)

References 33 publications

(46 reference statements)

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“…(For a review, the interested reader is referred to [1][2][3][4][5] and references therein.) Loop quantum gravity has already been successful in answering the question of the origin of black hole entropy [6][7][8][9][10][11][12][13][14][15][16][17][18]. In the paradigm of LQG this entropy has been shown to arise from counting the number of quantum microstates which yield a macroscopic black hole of fixed area.…”

Section: Introductionmentioning

confidence: 99%

Evolution ofΛblack holes in the minisuperspace approximation of loop quantum gravity

2009

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Using the improved quantization technique to the minisuperspace approximation of loop quantum gravity, we study the evolution of black holes supported by a cosmological constant. The addition of a cosmological constant allows for classical solutions with planar, cylindrical, toroidal, and higher-genus black holes. Here we study the quantum analog of these space-times. In all scenarios studied, the singularity present in the classical counterpart is avoided in the quantized version and is replaced by a bounce, and in the late evolution, a series of less severe bounces. Interestingly, although there are differences during the evolution between the various symmetries and topologies, the evolution on the other side of the bounce asymptotes to space-times of Nariai-type, with the exception of the planar black hole analyzed here, whose T-R ¼ constant subspaces seem to continue expanding in the long-term evolution. For the other cases, Nariai-type universes are attractors in the quantum evolution, albeit with different parameters. We study here the quantum evolution of each symmetry in detail.

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Section: Introductionmentioning

confidence: 99%

Evolution ofΛblack holes in the minisuperspace approximation of loop quantum gravity

2009

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“…j is an SU(2) parameter which is associated with the link of the spin network state in LQG (we assume j is sufficiently large), and γ is the Barbero-Immirzi parameter which is here assumed γ = ln(2)/(π √ 3) by the black hole entropy argument in LQG [1], but see also Ref [24]. Note that a * is the characteristic scale factor in LQC: when the scale factor is smaller than a * , the LQC effects are remarkable.…”

Section: A the Loop Quantized Hamiltonianmentioning

confidence: 99%

Observational Constraints on a Power Spectrum From Super-Inflation in Loop Quantum Cosmology

Shimano

Harada

2012

The Twelfth Marcel Grossmann Meeting

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In loop quantum cosmology there may be a super-inflation phase in the very early universe, in which a single scalar field with a negative power-law potential V = −M 4 (φ/M ) β plays important roles. Since the effective horizon √ SD/H controls the behavior of quantum fluctuation instead of the usual Hubble horizon, we assume the following inflation scenario; the super-inflation starts when the quantum state of the scalar field emerges into the classical regime, and ends when the effective horizon becomes the Hubble horizon, and the effective horizon scale never gets shorter than the Planck length. From consistency with the WMAP 5-year data, we place a constraint on the parameters of the potential (β and M ) and the energy density at the end of the super-inflation, depending on the volume correction parameter n.

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“…The one adopted in the original paper [2,7,8] counts the surface freedom (b 1 , b 2 , · · · , b n ). The second counts the freedom for both j and m [10,11,13]. Here, for simplicity, we base our argument mainly on the second possibility.…”

Section: Number Countingmentioning

confidence: 99%