A Note on the Swampland Distance Conjecture

Kehagias, Alex; Riotto, Antonio

doi:10.1002/prop.201900099

“…This case shall be discussed later on in some more detail. Alternatively, one can use entropy arguments to estimate for a [60], or use arguments regarding black holes on dS spacetime [62], for both of which the exponent turns out to be of the same order of magnitude. However, at first, instead of guessing for a, we shall show how it must be necessarily smaller than the lower bound required in (11), if one has to recover the refined dS conjecture.…”

Section: Swampland Conjectures and Refinements Of The Tccmentioning

confidence: 99%

“…Then, our task is reduced to computing F k , since it will easily lead to the quantum contribution to the power spectrum by means of (61). For this, plug ( 57) and ( 59) into (62), which renders…”

Section: Stochastic Propertiesmentioning

confidence: 99%

Role of trans-Planckian modes in cosmology

Berera,

Brahma,

Calderón

2020

Preprint

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Motivated by the old trans-Planckian (TP) problem of inflationary cosmology, it has been conjectured that any consistent effective field theory should keep TP modes 'hidden' behind the Hubble horizon, so as to prevent them from turning classical and thereby affecting macroscopic observations. In this paper we present two arguments against the Hubble horizon being a scale of singular significance as has been put forward in the TP Censorship Conjecture (TCC). First, refinements of TCC are presented that allow for the TP modes to grow beyond the horizon while still keeping the de-Sitter conjecture valid. Second, we show that TP modes can turn classical even well within the Hubble horizon, which, as such, negates this rationale behind keeping them from crossing it. The role of TP modes is known to be less of a problem in warm inflation, because fluctuations start out usually as classical. This allows warm inflation to be more resilient to the TP problem compared to cold inflation. To understand how robust this is, we identity limits where quantum modes can affect the primordial power spectrum in one specific case.

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“…The fact that such a correlation may be motivated from holography has been considered in the past, see e.g. [1][2][3][10][11][12][13]. In the present work we argue that in a theory of QG the appropriate UV cut-off should be identified with the species scale [14], so that such correlations imply the presence of towers of states below Λ UV .…”

Section: Introductionmentioning

confidence: 57%

“…For the case of (quasi-)dS vacua, 12 one can use similar holographic arguments in order to constrain the validity of any EFT defined within it. Thus, since dS space has for any observer sitting at an arbitrary location a cosmological horizon defined at r = R dS ∼ V −1/2 0 in Schwarzschild coordinates, the entropy associated to such EFT cannot exceed the Gibbons-Hawking bound (which is once again an special instance of the more general covariant entropy bound along with the spacelike projection theorem), i.e.…”

Section: Entropy Constraints On Ds Vacua and Our Universementioning

confidence: 99%

IR/UV mixing, towers of species and swampland conjectures

Castellano

¹

,

Herráez

²

,

Ibáñez

³

2022

J. High Energ. Phys.

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By applying the Covariant Entropy Bound (CEB) to an EFT in a box of size 1/ΛIR one obtains that the UV and IR cut-offs of the EFT are necessarily correlated. We argue that in a theory of Quantum Gravity (QG) one should identify the UV cutoff with the ‘species scale’, and give a general algorithm to calculate it in the case of multiple towers becoming light. One then obtains an upper bound on the characteristic mass scale of the tower in terms of the IR cut-off, given by Mtower ≲ $$ {\left({\Lambda}_{\mathrm{IR}}\right)}^{2{\alpha}_D} $$ Λ IR 2 α D in Planck units, with αD = (D − 2 + p)/2p(D − 1), where p depends on the density of states. Identifying the IR cut-off with a (non-vanishing) curvature in AdS one reproduces the statement of the AdS Distance Conjecture (ADC), also giving an explicit lower bound for the α exponent. In particular, we find that the CEB implies α ≥ 1/2 in any dimension if there is a single KK tower, both in AdS and dS vacua. However values α < 1/2 are allowed if the particle tower is multiple or has a string component. We also consider the CKN constraint coming from avoiding gravitational collapse which further requires in general α ≥ 1/D for the lightest tower. We analyse the case of the DGKT-CFI class of Type IIA orientifold models and show it has both particle and string towers below the species scale, so that a careful analysis of how the ADC is defined is needed. We find that this class of models obey but do not saturate the CEB. The UV/IR constraints found apply to both AdS and dS vacua. We comment on possible applications of these ideas to the dS Swampland conjecture as well as to the observed dS phase of the universe.

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“…This case shall be discussed later on in some more detail. Alternatively, one can use entropy arguments to estimate for a [61,62], or use arguments regarding black holes on dS spacetime [64], for both of which the exponent turns out to be of the same order of magnitude. However, at first, instead of guessing for a, we shall show how it must be necessarily smaller than the lower bound required JHEP08(2020)071…”

Section: Jhep08(2020)071 2 Swampland Conjectures and Refinements Of Thementioning

confidence: 99%

Role of trans-Planckian modes in cosmology

Berera

¹

,

Brahma

²

,

Calderón

³

2020

J. High Energ. Phys.

View full text Add to dashboard Cite

Motivated by the old trans-Planckian (TP) problem of inflationary cosmology, it has been conjectured that any consistent effective field theory should keep TP modes 'hidden' behind the Hubble horizon, so as to prevent them from turning classical and thereby affecting macroscopic observations. In this paper we present two arguments against the Hubble horizon being a scale of singular significance as has been put forward in the TP Censorship Conjecture (TCC). First, refinements of TCC are presented that allow for the TP modes to grow beyond the horizon while still keeping the de-Sitter conjecture valid. Second, we show that TP modes can turn classical even well within the Hubble horizon, which, as such, negates this rationale behind keeping them from crossing it. The role of TP modes is known to be less of a problem in warm inflation, because fluctuations start out usually as classical. This allows warm inflation to be more resilient to the TP problem compared to cold inflation. To understand how robust this is, we identity limits where quantum modes can affect the primordial power spectrum in one specific case.

show abstract

A Note on the Swampland Distance Conjecture

Cited by 6 publications

References 44 publications

Role of trans-Planckian modes in cosmology

Role of trans-Planckian modes in cosmology

IR/UV mixing, towers of species and swampland conjectures

Role of trans-Planckian modes in cosmology

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