Perturbative quantum gravity comes of age

Woodard, R. P.

doi:10.1142/s0218271814300201

Cited by 82 publications

(93 citation statements)

References 291 publications

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“…Regarding the 3rd point, one should note that the ζ-ζ propagator contains a factor of 1/ǫ(t) which is usually assumed to be cancelled by powers of ǫ(t) from the vertices [51]. However, it seems possible that the propagatorwhich depends nonlocally on ǫ(t) -might receive significant contributions from small, early values of ǫ(t).…”

Section: Introductionmentioning

confidence: 99%

“…If so, one might expect loop corrections from vertices at late times to be enhanced by large factors of ǫ late /ǫ early . A closely related issue is deciding what time best describes the putative loop counting parameter of GH 2 (t) [51]. A different sort of application concerns nonlocal modified gravity models of cosmology which are conjectured to represent quantum gravitational effects that became nonperturbatively strong during primordial inflation [52,53,54].…”

Section: Introductionmentioning

confidence: 99%

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Precision predictions for the primordial power spectra of scalar potential models of inflation

2016

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We exploit a new numerical technique for evaluating the tree order contributions to the primordial scalar and tensor power spectra for scalar potential models of inflation. Among other things we use the formalism to develop a good analytic approximation which goes beyond generalized slow roll expansions in that (1) it is not contaminated by the physically irrelevant phase, (2) its 0th order term is exact for constant first slow roll parameter, and (3) the correction is multiplicative rather than additive. These features allow our formalism to capture at first order, effects which are higher order in other expansions. Although this accuracy is not necessary to compare current data with any specific model, our method has a number of applications owing to the simpler representation it provides for the connection between the power spectra and the expansion history of a general model.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Precision predictions for the primordial power spectra of scalar potential models of inflation

2016

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“…As in flat spacetime, particles with smaller masses persist longer. Any massless particle which happens to emerge from the vacuum with sufficiently small wave number k Ha(t), where H is the expansion rate, a(t) is the cosmic scale factor, and t is the comoving time, can persist forever [7][8][9]. However, the particle production rate is suppressed for conformally invariant particles.…”

Section: Introductionmentioning

confidence: 99%

Vacuum fluctuations of a scalar field during inflation: Quantum versus stochastic analysis

Onemli

2015

Phys. Rev. D

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We consider an infrared truncated massless minimally coupled scalar field with a quartic self-interaction in the locally de Sitter background of an inflating universe.We compute the two-point correlation function of the scalar at one and two-loop order applying quantum field theory. The tree-order correlator at a fixed comoving separation (that is at increasing physical distance) freezes in to a nonzero value.At a fixed physical distance, it grows linearly with comoving time. The one-loop correlator, which is the dominant quantum correction, implies a negative temporal growth in the correlation function, at this order, at a fixed comoving separation and at a fixed physical distance. We also obtain quantitative results for variance in space and time of one and two-loop correlators and infer that the contrast between the vacuum expectation value and the variance becomes less pronounced when the loop corrections are included. Finally, we repeat the analysis of the model applying a stochastic field theory and reach the same conclusions.

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“…In addition, no convincing dynamical mechanism has so far been presented, which would explain the present small value of Λ as the evolution of an initially large value responsible for the inflationary period in the early universe, see e.g. [2][3][4]. As a result, we are instead facing the additional coincidence puzzle of why its corresponding energy density happened to be today of the same order of magnitude as the matter density in the Universe.…”

Section: Introductionmentioning

confidence: 95%