Asymptotic Accelerated Expansion in String Theory and the Swampland

Calderón-Infante, José; Ruíz, Ignacio Montero; Valenzuela, Irene

doi:10.48550/arxiv.2209.11821

Cited by 6 publications

(10 citation statements)

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“…We note that in string theory 'flat' exponentials do not occur; current evidence suggests that λ > √ 2 and accelerated expansion cannot occur (e.g. see [654,287,655,656,657] for recent discussions).…”

Section: The Overshoot Problemmentioning

confidence: 75%

“…Ref. [657] shows that the no-go theorems for single-field runaway quintessence in 4-dimensional N = 1 supergravity can be evaded by considering saxionic multi-field models. Again focusing on regions of the moduli space at infinite field distance, which give parametric control as the weak coupling parameter in the relevant perturbative expansion goes to zero in that limit, the multi-field trajectories found turn out to be geodesic ones.…”

Section: Multi-field Quintessencementioning

confidence: 99%

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String Cosmology: from the Early Universe to Today

Cicoli¹,

Conlon²,

Maharana³

et al. 2023

Preprint

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We review applications of string theory to cosmology, from primordial times to the present-day accelerated expansion. Starting with a brief overview of cosmology and string compactifications, we discuss in detail moduli stabilisation, inflation in string theory, the impact of string theory on post-inflationary dynamics (reheating, moduli domination, kination), dark energy (the cosmological constant from a string landscape and models of quintessence) and various alternative scenarios (string/brane gases, the pre big-bang scenario, rolling tachyons, ekpyrotic/cyclic cosmologies, bubbles of nothing, S-brane and holographic cosmologies). The state of the art in string constructions is described in each topic and, where relevant, connections to swampland conjectures are made. The possibilities for novel particles and excitations (axions, moduli, cosmic strings, branes, solitons, oscillons and boson stars) are emphasised. Implications for the physics of the CMB, gravitational waves, dark matter and dark radiation are discussed along with potential observational signatures.

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Section: The Overshoot Problemmentioning

confidence: 75%

Section: Multi-field Quintessencementioning

confidence: 99%

String Cosmology: from the Early Universe to Today

Cicoli¹,

Conlon²,

Maharana³

et al. 2023

Preprint

View full text Add to dashboard Cite

show abstract

“…The bound in eq. ( 2) that we derived provides us with a necessary condition to quickly diagnose whether cosmic acceleration is even possible at all, with a much wider applicability than previous studies [7,13,14]; we also stress that, even if the bound does not rule out cosmic acceleration, one then needs to identify whether the expansion is actually accelerated. The fact that the presence of negative-definite terms in the potential relaxes the bounds on acceleration resonates with the other wellknown no-go results [15][16][17], but it sharpens the specific situation of multi-field multi-exponential potentials in that it provides a quantitative restriction.…”

Section: Discussionmentioning

confidence: 76%

Accelerating universe at the end of time

Shiu¹,

Tonioni²,

Tran³

2023

Preprint

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We investigate whether an accelerating universe can be realized as an asymptotic late-time solution of FLRW-cosmology with multi-field multi-exponential potentials. Late-time cosmological solutions exhibit a universal behavior which enables us to bound the rate of time variation of the Hubble parameter. In string-theoretic realizations, if the dilaton remains a rolling field, our bound singles out a tension in achieving asymptotic late-time cosmic acceleration. Our findings go beyond previous no-go theorems in that they apply to arbitrary multi-exponential potentials and make no specific reference to vacuum or slow-roll solutions. We also show that if the late-time solution approaches a critical point of the dynamical system governing the cosmological evolution, the criterion for cosmic acceleration can be generally stated in terms of a directional derivative of the potential.

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“…We thus expect the consistent truncation S 4d of (4.2) to be part of the 4d effective action, and thus subject to e.g. the analysis and constraints presented recently in [37].…”

Section: Jhep01(2023)033mentioning

confidence: 90%

“…In particular, the analysis of [23] could be relevant for the swampland conjecture [24]. Cosmological solutions of gauged supergravities and F-theory have been studied in [25][26][27][28][29][30][31][32][33][34][35][36][37].…”

Section: Jhep01(2023)033mentioning

confidence: 99%

Universal accelerating cosmologies from 10d supergravity

Marconnet

Tsimpis

2023

J. High Energ. Phys.

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We study 4d Friedmann-Lemaître-Robertson-Walker cosmologies obtained from time-dependent compactifications of Type IIA 10d supergravity on various classes of 6d manifolds (Calabi-Yau, Einstein, Einstein-Kähler). The cosmologies we present are universal in that they do not depend on the detailed features of the compactification manifold, but only on the properties which are common to all the manifolds belonging to that class. Once the equations of motion are rewritten as an appropriate dynamical system, the existence of solutions featuring a phase of accelerated expansion is made manifest. The fixed points of this dynamical system, as well as the trajectories on the boundary of the phase space, correspond to analytic solutions which we determine explicitly. Furthermore, some of the resulting cosmologies exhibit eternal or semi-eternal acceleration, whereas others allow for a parametric control on the number of e-foldings. At future infinity, one can achieve both large volume and weak string coupling. Moreover, we find several smooth accelerating cosmologies without Big Bang singularities: the universe is contracting in the cosmological past (T < 0), expanding in the future (T > 0), while in the vicinity of T = 0 it becomes de Sitter in hyperbolic slicing. We also obtain several cosmologies featuring an infinite number of cycles of alternating periods of accelerated and decelerated expansions.

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Asymptotic Accelerated Expansion in String Theory and the Swampland

Cited by 6 publications

References 0 publications

String Cosmology: from the Early Universe to Today

String Cosmology: from the Early Universe to Today

Accelerating universe at the end of time

Universal accelerating cosmologies from 10d supergravity

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