Kalb-Ramond backgrounds in α'-complete cosmology

Article Physics, Particles & Fields

New non-perturbative de Sitter vacua in α′-complete cosmology

Carmen A. Nunez et al.

Summary: The alpha ' -complete cosmology developed by Hohm and Zwiebach categorizes O(d, d; ) invariant theories and explores the construction and properties of non-perturbative de Sitter solutions within this theoretical framework.

JOURNAL OF HIGH ENERGY PHYSICS (2021)

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Article Physics, Particles & Fields

de Sitter space as a Glauber-Sudarshan state

Suddhasattwa Brahma et al.

Summary: In this paper, de Sitter space is identified as a coherent state, which can only be realized in full string theory when combined with temporally varying degrees of freedom and quantum corrections. Viewing de Sitter space as a state rather than a vacuum resolves many issues associated with its entropy, zero-point energy, and trans-Planckian censorship.

JOURNAL OF HIGH ENERGY PHYSICS (2021)

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Article Physics, Particles & Fields

de Sitter vacua in the string landscape

Keshav Dasgupta et al.

Summary: The study focuses on finding time-dependent backgrounds in string theory that allow positive dark energies, showing challenges at both classical and quantum levels. By including various quantum terms, it reveals the emergence of a four-dimensional positive curvature space-time with de Sitter isometrics and time-independent Newton's constant in the landscape of type IIB string theory, avoiding no-go and swampland criteria associated with backgrounds with time-dependent Newton constants.

NUCLEAR PHYSICS B (2021)

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Article Physics, Particles & Fields

Cosmology at the top of the α′ tower

Jerome Quintin et al.

Summary: This paper revisits the cosmology of the fully alpha'-corrected duality-invariant action for the Neveu-Schwarz sector of string theory, with a special emphasis on its coupling to matter sources. The role of duality covariant pressure and dilatonic charge of the matter sector is explored in various contexts, from the low-curvature regime to non-perturbative solutions in alpha'.

JOURNAL OF HIGH ENERGY PHYSICS (2021)

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Article Physics, Particles & Fields

Cosmological α′-corrections from the functional renormalization group

Ivano Basile et al.

Summary: In this study, the Functional Renormalization Group techniques were applied in string theory to derive an effective mini-superspace action for cosmological backgrounds in terms of the string scale alpha '. T-duality played a crucial role in classifying perturbative curvature corrections, leading to renormalization group equations with exact solutions in any spacetime dimension D. While an analytic solution with a non-Gaussian ultraviolet fixed point was found around D = 2, no analogous solution was found in D = 4 using polynomial truncations. The study also discussed potential cosmological implications of the findings.

JOURNAL OF HIGH ENERGY PHYSICS (2021)

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Article Astronomy & Astrophysics

String cosmology backgrounds from classical string geometry

Heliudson Bernardo et al.

Summary: The paper introduces a model of the early universe based on the thermodynamics of a gas of closed strings, describing the evolution of the system in three different stages parametrized by the gas's equation of state, leading to a universe with four large spacetime dimensions and six stabilized internal dimensions.

PHYSICAL REVIEW D (2021)

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Article Physics, Particles & Fields