Limitations of an effective field theory treatment of early Universe cosmology

Brandenberger, Robert H.

doi:10.1098/rsta.2021.0178

Cited by 10 publications

(11 citation statements)

References 92 publications

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“…The UV divergence is logarithmic and of the form ln (Λ/H). 5 This is what is commonly expected in loop corrections for inflationary perturbations.…”

Section: Uv and Ir Divergencessupporting

confidence: 56%

“…This typically goes under the name of the 'trans-Planckian problem' of inflationary cosmology [3,4]. Simply put, classical inhomogeneities observed at late times, if traced back long enough, could have arisen from trans-Planckian modes, a regime in which the predictions of inflation cannot be trusted anymore [5]. Instead of going into the debate of understanding the pros and cons of whether this is indeed a physical problem (see, e.g.…”

Section: Introductionmentioning

confidence: 99%

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Quantum corrections to the primordial tensor spectrum: Open EFTs & Markovian decoupling of UV modes

Brahma,

Berera,

Calderón-Figueroa

2022

Preprint

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Perturbative quantum corrections to primordial power spectra are important for testing the robustness and the regime of validity of inflation as an effective field theory. Although this has been done extensively for the density power spectrum (and, to some extent, for the tensor spectrum) using loop corrections, we do so in an open quantum system approach to the problem. Specifically, we calculate the first order corrections to the primordial gravitational wave spectrum due to (cubic) tensor interactions alone. We show that our results match expectations from standard loop corrections only in the strict Markovian limit, and therefore, establish a systematic way to relax this approximation in the future, as is generally necessary for gravitational systems.

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“…The UV divergence is logarithmic and of the form ln (Λ/H). 5 This is what is commonly expected in loop corrections for inflationary perturbations.…”

Section: Uv and Ir Divergencessupporting

confidence: 56%

Section: Introductionmentioning

confidence: 99%

Quantum corrections to the primordial tensor spectrum: Open EFTs & Markovian decoupling of UV modes

Brahma,

Berera,

Calderón-Figueroa

2022

Preprint

View full text Add to dashboard Cite

show abstract

“…problem' of inflationary cosmology [3,4]. Simply put, classical inhomogeneities observed at late times, if traced back long enough, could have arisen from trans-Planckian modes, a regime in which the predictions of inflation cannot be trusted anymore [5]. Instead of going into the debate of understanding the pros and cons of whether this is indeed a physical problem (see, e.g.…”

Section: Jhep08(2022)225mentioning

confidence: 99%

“…The UV divergent terms appear as i ln Λ, and therefore, fall out of the final expression due to adding in its complex conjugate. 5 This is not strange at all -all this suggests is that although we need to put in a cutoff to regulate momentum integrals in the intermediate steps, the physical result is independent of such cutoffs simply due to how the UV divergences appears in them.…”

Section: Uv and Ir Divergencesmentioning

confidence: 99%

Quantum corrections to the primordial tensor spectrum: open EFTs & Markovian decoupling of UV modes

Brahma

Berera

Calderón-Figueroa

2022

J. High Energ. Phys.

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Perturbative quantum corrections to primordial power spectra are important for testing the robustness and the regime of validity of inflation as an effective field theory. Although this has been done extensively for the density power spectrum (and, to some extent, for the tensor spectrum) using loop corrections, we do so in an open quantum system approach to the problem. Specifically, we calculate the first-order corrections to the primordial gravitational wave spectrum due to (cubic) tensor interactions alone. We show that our results match expectations from standard loop corrections only in the strict Markovian limit, and therefore, establish a systematic way to relax this approximation in the future, as is generally necessary for gravitational systems.

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“…Studies of perturbative unitarity in cosmology may throw some light upon the unknown new physics related to the very early universe, see e.g., [90][91][92][93][94][95][96][97][98]. It would be interesting to see what the constraints of perturbative unitarity can tell about those higher derivative operators which are essential in fully stable NEC-violating nonsingular cosmology, see also [92] for the case of P (X) theory in the context of bouncing cosmology.…”

Section: Introductionmentioning

confidence: 99%

Perturbative unitarity and NEC violation in genesis cosmology

Cai¹,

Xu²,

Zhou³

2022

Preprint

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Explorations of the violation of null energy condition (NEC) in cosmology could enrich our understanding of the very early universe and the related gravity theories. Although a fully stable NEC violation can be realized in the "beyond Horndeski" theory, it remains an open question whether a violation of the NEC is allowed by some fundamental properties of UV-complete theories or the consistency requirements of effective field theory (EFT). We investigate the tree-level perturbative unitarity for stable NEC violations in the contexts of both Galileon and "beyond Horndeski" genesis cosmology, in which the universe is asymptotically Minkowskian in the past. We find that the constraints of perturbative unitarity imply that we may need some unknown new physics below the cut-off scale of the EFT other than that represented by the "beyond Horndeski" operators.

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Limitations of an effective field theory treatment of early Universe cosmology

Cited by 10 publications

References 92 publications

Quantum corrections to the primordial tensor spectrum: Open EFTs & Markovian decoupling of UV modes

Quantum corrections to the primordial tensor spectrum: Open EFTs & Markovian decoupling of UV modes

Quantum corrections to the primordial tensor spectrum: open EFTs & Markovian decoupling of UV modes

Perturbative unitarity and NEC violation in genesis cosmology

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