Nonvacuum AdS cosmology and comments on gauge theory correlator

Chatterjee, Soumyabrata; Chowdhury, Sudipto Paul; Mukherji, Sudipta; Srivastava, Yogesh Kumar

doi:10.1103/physrevd.95.046011

Cited by 5 publications

(6 citation statements)

References 38 publications

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“…In the next section, we will generalise these results to a 1-parameter family of quantum corrected metrics labelled by λ ≥ 0, from which the classical result can be obtained in the limit λ → 0. Further work generalising [5,6] to other classical cosmological spacetimes was done in [8].…”

Section: Cft Correlators From Classical Kasner Metricsmentioning

confidence: 99%

Holographic signatures of resolved cosmological singularities

Bodendorfer

Schäfer

Schliemann

2019

J. High Energ. Phys.

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The classical gravity approximation is often employed in AdS/CFT to study the dual field theory, as it allows for many computations. A drawback is however the generic presence of singularities in classical gravity, which limits the applicability of AdS/CFT to regimes where the singularities are avoided by bulk probes, or some other form of regularisation is applicable. At the same time, quantum gravity is expected to resolve those singularities and thus to extend the range of applicability of AdS/CFT also in classically singular regimes. This paper provides a proof of principle that such computations are already possible. We use a quantum corrected Kasner-AdS metric inspired by results from loop quantum gravity to compute the 2-point correlator in the geodesic approximation for a negative Kasner exponent. The correlator derived in the classical gravity approximation has previously been shown to contain a pole at finite distance as a signature of the singularity. Using the quantum corrected metric, we show explicitly how the pole is resolved and that a new subdominant long-distance contribution to the correlator emerges, caused by geodesics passing arbitrarily close to the resolved classical singularity. We stress that these results rely on several choices in the quantum corrected metric which allow for an analytic computation and may not hold in general. An alternative choice is presented where the correlator may remain singular even though the bulk singularity is resolved.

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Section: Cft Correlators From Classical Kasner Metricsmentioning

confidence: 99%

Holographic signatures of resolved cosmological singularities

Bodendorfer

Schäfer

Schliemann

2019

J. High Energ. Phys.

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“…The reason is that in this case the relations among the Kasner exponents get modified due to the presence of the dilaton and the radion field. It would be interesting to see what effect (such modification to Kasner solution at early time) it would have on the cosmological singularities [29][30][31].…”

Section: Resultsmentioning

confidence: 99%

Anisotropic SD2 brane: accelerating cosmology and Kasner-like space-time from compactification

Nayek

Roy

2017

Eur. Phys. J. C

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Starting from an anisotropic (in all directions including the time direction of the brane) non-SUSY D2 brane solution of type IIA string theory we construct an anisotropic space-like D2 brane (or SD2 brane, for short) solution by the standard trick of a double Wick rotation. This solution is characterized by five independent parameters. We show that compactification on six-dimensional hyperbolic space (H 6 ) of a time-dependent volume of this SD2 brane solution leads to accelerating cosmologies (for some time t ∼ t 0 , with t 0 some characteristic time) where both the expansions and the accelerations are different in three spatial directions of the resultant four-dimensional universe. On the other hand at early times (t t 0 ) this four-dimensional space, in certain situations, leads to four-dimensional Kasnerlike cosmology, with two additional scalars, namely, the dilaton and a volume scalar of H 6 . Unlike in the standard fourdimensional Kasner cosmology here all three Kasner exponents could be positive definite, leading to expansions in all three directions.

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“…After the bounce we can map back to the bulk and extract the information of the scale invariance when the gravity sector is becoming weakly coupled again. These references [72][73][74][75][76] inspire our work as well as many aspects of our method.…”

Section: Small σVmentioning

confidence: 99%

Following the primordial perturbations through a bounce with AdS/CFT correspondence

2018

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A bounce universe model, known as the coupled-scalar-tachyon bounce (CSTB) universe, has been shown to solve the Horizon, Flatness and Homogeneity problems as well as the Big Bang Singularity problem. Furthermore a scale invariant spectrum of primordial density perturbations generated from the phase of pre-bounce contraction is shown to be stable against time evolution. In this work we study the detailed dynamics of the bounce and its imprints on the scale invariance of the spectrum. The dynamics of the gravitational interactions near the bounce point may be strongly coupled as the spatial curvature becomes big. There is no a prior reason to expect the spectral index of the primordial perturbations of matter density can be preserved. By encoding the bounce dynamics holographically onto the dynamics of dual Yang-Mills system while the latter is weakly coupled, via the AdS/CFT correspondence, we can safely evolve the spectrum of the cosmic perturbations with full control. In this way we can compare the post-bounce spectrum with the pre-bounce one: in the CSTB model we explicitly show that the spectrum of primordial density perturbations generated in the contraction phase preserves its stability as well as scale invariance throughout the bounce process.Keywords AdS/CFT, primordial spectrum of density perturbations, bounce universe, early universe physics.

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Nonvacuum AdS cosmology and comments on gauge theory correlator

Cited by 5 publications

References 38 publications

Holographic signatures of resolved cosmological singularities

Holographic signatures of resolved cosmological singularities

Anisotropic SD2 brane: accelerating cosmology and Kasner-like space-time from compactification

Following the primordial perturbations through a bounce with AdS/CFT correspondence

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