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Universe 2018, 4(7), 80; https://doi.org/10.3390/universe4070080

A Scale at 10 MeV, Gravitational Topological Vacuum, and Large Extra Dimensions

1
School of Physics, Huazhong University of Science and Technology, Wuhan 430074, Hubei, China
2
Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala, Sweden
Received: 21 June 2018 / Revised: 15 July 2018 / Accepted: 16 July 2018 / Published: 18 July 2018
(This article belongs to the Special Issue Gravity, Black Holes and Cosmology XXI)
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Abstract

We discuss a possible scale of gravitational origin at around 10 MeV, or 1012 cm, which arises in the MacDowell–Mansouri formalism of gravity due to the topological Gauss–Bonnet term in the action, as pointed out by Bjorken several years ago. A length scale of the same size emerges also in the Kodama solution in gravity, which is known to be closely related to the MacDowell–Mansouri formulation. We particularly draw attention to the intriguing incident that the existence of six compact extra dimensions originated from TeV-scale quantum gravity as well points to a length scale of 1012 cm, as the compactification scale. The presence of six such extra dimensions is also in remarkable consistency with the MacDowell–Mansouri formalism; it provides a possible explanation for the factor of ∼10120 multiplying the Gauss–Bonnet term in the action. We also comment on the relevant implications of such a scale regarding the thermal history of the universe motivated by the fact that it is considerably close to 1–2 MeV below which the weak interactions freeze out, leading to Big Bang Nucleosynthesis. View Full-Text
Keywords: MacDowell–Mansouri formalism; Bjorken–Zeldovich scale; Gauss–Bonnet term; Einstein–Cartan formalism; Big Bang nucleosynthesis; cosmological constant; Kodama wavefunctions MacDowell–Mansouri formalism; Bjorken–Zeldovich scale; Gauss–Bonnet term; Einstein–Cartan formalism; Big Bang nucleosynthesis; cosmological constant; Kodama wavefunctions
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).
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Aydemir, U. A Scale at 10 MeV, Gravitational Topological Vacuum, and Large Extra Dimensions. Universe 2018, 4, 80.

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