Massless scalar fields and infrared divergences in the inflationary brane world

Pujolàs, Oriol; Tanaka, Takahiro

doi:10.1088/1475-7516/2004/12/009

Cited by 18 publications

(27 citation statements)

References 37 publications

(172 reference statements)

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“…Thus, we conclude that indeed in the regular vacuum state there is no particle creation, i.e., p 0 = 0. 7 This result is confirmed by the explicit 1-loop computations [35]- [38], [50] for scalar fields 8 , and is also expected from the analogy with moving mirrors [32]. As is well known, they only radiate to conformal fields if the motion is not uniformly accelerated, that is, if the worldvolume of the mirror is not maximally symmetric.…”

Section: Absence Of Particle Productionsupporting

confidence: 56%

“…8 These calculations also show that the vanishing of T µν (0) is independent of what kind of boundary conditions satisfied by the CFT fields at the DW location. Indeed, T µν (0) is found to vanish even introducing a coupling of the scalar field to the DW of the form m 0 δ(ξ)φ 2 [50]. The only effect of this at 1-loop is to renormalize the DW tension [51].…”

Section: )mentioning

confidence: 98%

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Dressed Domain Walls and holography

Grisa¹,

Pujolàs²

2008

J. High Energy Phys.

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The cutoff version of the AdS/CFT correspondence states that the Randall Sundrum scenario is dual to a Conformal Field Theory (CFT) coupled to gravity in four dimensions. The gravitational field produced by relativistic Domain Walls can be exactly solved in both sides of the correspondence, and thus provides one further check of it. We show in the two sides that for the most symmetric case, the wall motion does not lead to particle production of the CFT fields. Still, there are nontrivial effects. Due to the trace anomaly, the CFT effectively renormalizes the Domain Wall tension. On the five dimensional side, the wall is a codimension 2 brane localized on the Randall-Sundrum brane, which pulls the wall in a uniform acceleration. This is perceived from the brane as a Domain Wall with a tension slightly larger than its bare value. In both cases, the deviation from General Relativity appears at nonlinear level in the source, and the leading corrections match to the numerical factors. 1

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Section: Absence Of Particle Productionsupporting

confidence: 56%

Section: )mentioning

confidence: 98%

Dressed Domain Walls and holography

Grisa¹,

Pujolàs²

2008

J. High Energy Phys.

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“…The modes v ω , which are positive frequency with respect to the static time co-ordinate τ (with time dependence exp(−iωτ )), define the static vacuum while the modes f k in Eq. (43) and Eq. (56) define the Bunch-Davies vacuum, for massive and massless fields respectively.…”

Section: Static Co-ordinates and The Cosmic Vacuummentioning

confidence: 99%

Quantum correlators in Friedmann spacetimes: The omnipresent de Sitter spacetime and the invariant vacuum noise

et al. 2018

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We discuss several aspects of quantum field theory of a scalar field in a Friedmann universe. (i) We begin by showing that it is possible to map the dynamics of a scalar field with a given mass, in a given Friedmann background to another scalar field of a different mass in another Friedmann universe. In particular one can map the dynamics of (1) a massless scalar field in a universe with power-law expansion to (2) a massive scalar field in the de Sitter spacetime. This allows us to understand several features of either system in a simple manner and clarifies several issues related to the massless limit. (ii) We relate the Euclidean Green's function for the de Sitter spacetime to the solution of a hypothetical electrostatic problem in D=5 and obtain, in a very simple manner, a useful integral representation for the Green's function. This integral representation is helpful in the study of several relevant limits, and in recovering some key results which are -though known earlier -not adequately appreciated. One of these results is the fact that, in any Friedmann universe, sourced by a negative pressure fluid, the Wightman function for a massless scalar field is divergent. This shows that the divergence of Wightman function for the massless field in the de Sitter spacetime is just a special, limiting, case of this general phenomenon. (iii) We provide a generally covariant procedure for defining the power spectrum of vacuum fluctuations in terms of the different Killing vectors present in the spacetime. This allows one to study the interplay of the choice of vacuum state and the nature of the power spectrum in different co-ordinate systems, in the de Sitter universe, in a unified manner. (iv) As a specific application of this formalism, we discuss the power spectra of vacuum fluctuations in the static (and Painlevé) vacuum states in the de Sitter spacetime and compare them with the corresponding power spectrum in the Bunch-Davies vacuum. We demonstrate how these power spectra are related to each other in a manner similar to the power spectra detected by the inertial and Rindler observers in flat spacetime. This also gives rise to a notion of an invariant vacuum noise in the corresponding spacetimes which is observer independent. (v) In addition, several conceptual and technical issues regarding quantum fields in general cosmological spacetimes are clarified as a part of this study. * kinjalk@iisermohali.ac.in † karthik@iucaa.in ‡

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“…Then, the larger root of f (R) is Figure 7: Hyperbolic AdS solitons with different 'radii' ∆θ can be represented as disks of different sizes. Every point represents an AdS 3 with a curvature radius given by (51) at the origin while at infinity it grows as fast as the circle spanned by θ. The boundary is of the form S 1 × AdS 3 , and the length of the S 1 in units of the AdS 3 radius is ∆θ, (52).…”

Section: A Ignoring the Backreaction (The Brane)mentioning

confidence: 99%

“…Finally, let us point out that the curvature scale on the string is −1/R 2 + with R + given in (51), so this also depends on the string tension. Hence, one obtains a nontrivial 'Friedmann equation' (understood as the relation between the curvature scale and the tension or energy density on the defect; this is more relevant for the generalization of the present example to 6D, in which case the CS would be a 3+1 brane).…”

Section: Epilogue: Cosmic Strings In Adsmentioning

confidence: 99%

Strongly coupled radiation from moving mirrors and holography in the Karch-Randall model

Pujolàs

2008

J. High Energy Phys.

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Motivated by the puzzles in understanding how Black Holes evaporate into a strongly coupled Conformal Field Theory, we study particle creation by an accelerating mirror. We model the mirror as a gravitating Domain Wall and consider a CFT coupled to it through gravity, in asymptotically Anti de Sitter space. This problem (backreaction included) can be solved exactly at one loop. At strong coupling, this is dual to a Domain Wall localized on the brane in the Karch-Randall model, which can be fully solved as well. Hence, in this case one can see how the particle production is affected by A) strong coupling and B) its own backreaction. We find that A) the amount of CFT radiation at strong coupling is not suppressed relative to the weak coupling result; and B) once the boundary conditions in the AdS 5 bulk are appropriately mapped to the conditions for the CFT on the boundary of AdS 4 , the Karch-Randall model and the CFT side agree to leading order in the backreaction. This agreement holds even for a new class of self-consistent solutions (the 'Bootstrap' Domain Wall spacetimes) that have no classical limit. This provides a quite precise check of the holographic interpretation of the Karch-Randall model. We also comment on the massive gravity interpretation.As a byproduct, we show that relativistic Cosmic Strings (pure tension codimension 2 branes) in Anti de Sitter are repulsive and generate long-range tidal forces even at classical level. This is the phenomenon dual to particle production by Domain Walls.

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Massless scalar fields and infrared divergences in the inflationary brane world

Cited by 18 publications

References 37 publications

Dressed Domain Walls and holography

Dressed Domain Walls and holography

Quantum correlators in Friedmann spacetimes: The omnipresent de Sitter spacetime and the invariant vacuum noise

Strongly coupled radiation from moving mirrors and holography in the Karch-Randall model

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