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

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## Abstract

**:**

## 1. Introduction

## 2. The MacDowell–Mansouri Formalism and the Bjorken–Zeldovich Scale

## 3. Bjorken–Zeldovich Scale from Large Extra Dimensions

## 4. A “See-Saw” Relation for the Small Cosmological Constant and the Neutrino Mass?

## 5. More on the Relevance in Cosmology

## 6. Discussion

## Funding

## Acknowledgments

## Conflicts of Interest

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1 | Recently, the Atomki group in Hungary reported an anomaly in the ${}^{8}$Be nuclear decay by internal ${e}^{+}{e}^{-}$ formation at an invariant mass ${m}_{\overline{e}e}\cong 17$ MeV, with a statistical significance of 6.8$\sigma $ [33]. See also Refs. [34,35,36,37,38,39,40,41,42] for the previous studies relevant to this observation. The observation has ignited interest in the high energy physics community to suggest explanations, some of which consider a hidden sector at around this energy scale whose effects have so far remained unnoticed [43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61]. |

2 | |

3 |

**Figure 1.**Compactification radius R vs. quantum gravity scale ${M}_{U}$ in the case of six large extra dimensions. The black and orange plots denote the cases in which ${M}_{U}$ takes values below and above 1 TeV, respectively.

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Aydemir, U. A Scale at 10 MeV, Gravitational Topological Vacuum, and Large Extra Dimensions. *Universe* **2018**, *4*, 80.
https://doi.org/10.3390/universe4070080

**AMA Style**

Aydemir U. A Scale at 10 MeV, Gravitational Topological Vacuum, and Large Extra Dimensions. *Universe*. 2018; 4(7):80.
https://doi.org/10.3390/universe4070080

**Chicago/Turabian Style**

Aydemir, Ufuk. 2018. "A Scale at 10 MeV, Gravitational Topological Vacuum, and Large Extra Dimensions" *Universe* 4, no. 7: 80.
https://doi.org/10.3390/universe4070080