Ultraviolet sensitivity of the cosmological sequester

Lawrence, Michaela G.; Seery, David

doi:10.48550/arxiv.2007.07058

Cited by 2 publications

(4 citation statements)

References 27 publications

(77 reference statements)

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“…In particular, 1PI matter and graviton loops modify the cosmological constant, while pure gravity loops are responsible for the corrections to the gravitational coupling. An exhaustive analysis of the different effects of the quantum corrections and the ultraviolet sensitivity of sequestering, both in the Jordan and Einstein frames, is presented in reference [58]. In the case of the sequestering model, it has been shown that to cope with graviton loops the local model must be extended [59].…”

Section: Graviton Loopsmentioning

confidence: 99%

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Exploring the self-tuning of the cosmological constant from Planck mass variation

Sobral-Blanco¹,

Lombriser²

2021

Class. Quantum Grav.

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Recently, the variation of the Planck mass in the general relativistic Einstein–Hilbert action was proposed as a self-tuning mechanism of the cosmological constant, preventing standard model vacuum energy from freely gravitating and enabling an estimation of the magnitude of its observed value. We explore here new aspects of this proposal. We first develop an equivalent Einstein-frame formalism to the current Jordan-frame formulation of the mechanism and use this to highlight similarities and differences of self-tuning to the sequestering mechanism. We then show how with an extension of the local self-tuning action by a coupled Gauss–Bonnet term and a companion four-form field strength, graviton loops can be prevented from incapacitating the degravitation of the standard model vacuum energy. For certain cases, we furthermore find that this extension can be recast as a Horndeski scalar–tensor theory and be embedded in the conventional local self-tuning formalism. We then explore the possibility of a unification of inflation with self-tuning. The resulting equations can alternatively be used to motivate a multiverse interpretation. In this context, we revisit the coincidence problem and provide an estimation for the probability of the emergence of intelligent life in our Universe as a function of cosmic age, inferred from star and terrestrial planet formation processes. We conclude that we live at a very typical epoch, where we should expect the energy densities of the cosmological constant and matter to be of comparable size. For a dimensionless quantity to compare the emergence of life throughout the cosmic history of different universes in an anthropic analysis of the multiverse, we choose the order of magnitude difference of the evolving horizon size of a Universe to the size of its proton as the basic building block of atoms, molecules, and eventually life. For our Universe we find this number to form peak at approximately 42. We leave the question of whether the same number is frequently assumed for the emergence of life across other universes or singles out a special case to future exploration.

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Section: Graviton Loopsmentioning

confidence: 99%

“…This yields a constraint that is a polynomial in the difference Λ − T /4. Moreover, when the variational constraint is not explicitly dependent on M 2 P , all of the Planck mass dependent contributions cancel from the residual energy-momentum tensor, at least to leading order [58,59].…”

Section: The Gauss-bonnet Invariantmentioning

confidence: 99%

Exploring the self-tuning of the cosmological constant from Planck mass variation

Sobral-Blanco¹,

Lombriser²

2021

Class. Quantum Grav.

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show abstract

“…An exhaustive analysis of the different effects of the quantum corrections and the ul-traviolet sensitivity of sequestering, both in the Jordan and Einstein frames, is presented in Ref. [56]. In the case of the sequestering model, it has been shown that to cope with graviton loops the local model must be extended [57].…”

Section: Graviton Loopsmentioning

confidence: 99%

Section: A the Gauss-bonnet Invariantmentioning

confidence: 99%

Exploring the self-tuning of the cosmological constant from Planck mass variation

Sobral-Blanco¹,

Lombriser²

2020

Preprint

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Recently, the variation of the Planck mass in the General Relativistic Einstein-Hilbert action was proposed as a self-tuning mechanism of the cosmological constant, preventing Standard Model vacuum energy from freely gravitating and enabling an estimation of the magnitude of its observed value. We explore here new aspects of this proposal. We first develop an equivalent Einstein-frame formalism to the current Jordan-frame formulation of the mechanism and use this to highlight similarities and differences of self-tuning to the sequestering mechanism. We then show how with an extension of the local self-tuning action by a coupled Gauss-Bonnet term and a companion four-form field strength, graviton loops can be prevented from incapacitating the degravitation of the Standard Model vacuum energy. For certain cases, we furthermore find that this extension can be recast as a Horndeski scalar-tensor theory and be embedded in the conventional local self-tuning formalism. We then explore the possibility of a unification of inflation with self-tuning. The resulting equations can alternatively be used to motivate a multiverse interpretation. In this context, we revisit the coincidence problem and provide an estimation for the probability of the emergence of intelligent life in our Universe as a function of cosmic age, inferred from star and terrestrial planet formation processes. We conclude that we live at a very typical epoch, where we should expect the energy densities of the cosmological constant and matter to be of comparable size. For a dimensionless quantity to meaningfully compare the emergence of life throughout the cosmic history of different universes in an anthropic analysis of the multiverse, we introduce the order of magnitude difference of the evolving horizon size of a universe to the size of its proton as the basic building block of atoms, molecules, and eventually life. For our Universe we find this number to form peak at approximately 42. We leave the question of whether the same number must be assumed for the emergence of life across other universes to future exploration.

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Ultraviolet sensitivity of the cosmological sequester

Cited by 2 publications

References 27 publications

Exploring the self-tuning of the cosmological constant from Planck mass variation

Exploring the self-tuning of the cosmological constant from Planck mass variation

Exploring the self-tuning of the cosmological constant from Planck mass variation

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