On thermal field fluctuations in ghost-free theories

Boos, Jens; Frolov, Valeri P.; Zelnikov, Andrei

doi:10.1016/j.physletb.2019.04.059

Cited by 14 publications

(7 citation statements)

References 32 publications

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“…This simple example shows in a clear fashion how causality is violated in nonlocal theories. We remand the reader to the literature [81][82][83][84][85] for a detailed discussion of the causality violation in the scattering amplitudes.…”

Section: )mentioning

confidence: 99%

Unattainability of the trans-Planckian regime in nonlocal quantum gravity

Briscese

Modesto

2020

J. High Energ. Phys.

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Based on the ultraviolet asymptotic freedom of nonlocal quantum gravity, we show that the trans-Planckian energy regime is unattainable in laboratory experiments. As physical implications, it turns out that the violation of causality, typical of nonlocal field theories, can never be detected in particle accelerators, while the asymptotic freedom of the theory provides an elegant solution to the so called trans-Planckian cosmological problem.

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Section: )mentioning

confidence: 99%

Unattainability of the trans-Planckian regime in nonlocal quantum gravity

Briscese

Modesto

2020

J. High Energ. Phys.

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“…This allows the intriguing possibility of observing this nonlocal scale at low energies, allowing us to constrain or falsify the theory [54,55]. Furthermore, infinite derivative theories have very interesting quantum properties at finite temperatures [56][57][58][59][60], which mimics some properties of the Hagedorn behavior of strings at temperatures above the string scale. In addition to all these developments, it is important to study classical perturbations of IDG in four spacetime dimensions.…”

Section: Introductionmentioning

confidence: 98%

Perturbations in higher derivative gravity beyond maximally symmetric spacetimes

2019

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We study (covariant) scalar-vector-tensor (SVT) perturbations of infinite derivative gravity (IDG), at the quadratic level of the action, around conformally flat, covariantly constant curvature backgrounds that are not maximally symmetric spacetimes (MSS). This extends a previous analysis of perturbations done around MSS, which were shown to be ghost-free. We motivate our choice of backgrounds that arise as solutions of IDG in the UV, avoiding big bang and black hole singularities. Contrary to MSS, in this paper we show that, generically, all SVT modes are coupled to each other at the quadratic level of the action. We consider simple examples of the full IDG action, and we illustrate this mixing and also a case where the action can be diagonalized and a ghost-free spectrum constructed. Our study is widely applicable for both nonsingular cosmology and black hole physics where backgrounds depart from MSS. In the appendixes, we provide SVT perturbations around conformally flat and arbitrary backgrounds which can serve as a compendium of useful results when studying various higher derivative gravity models.

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“…IDG theories are also motivated from particle limit of strings [17][18][19], and have been argued to have no singular static solution. At a quantum level, infinite derivative field theories, with similar propagator, bring softening of UV divergences [20][21][22][23][24][25][26][27][28][29][30] such as shifting the scale of non-locality with large number of external legs interacting non-locally [31].…”

Section: Introductionmentioning

confidence: 99%