Cosmic eggs to relax the cosmological constant

Jan 5, 2021
17 pages
Published in:
  • JCAP 08 (2021) 064
  • Published: Aug 31, 2021
e-Print:

Citations per year

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Abstract: (IOP)
In theories with extra dimensions, the cosmological hierarchy problem can be thought of as the unnaturally large radius of the observable universe in Kaluza-Klein units. We sketch a dynamical mechanism that relaxes this. In the early universe scenario we propose, three large spatial dimensions arise through tunneling from a `cosmic egg', an effectively one-dimensional configuration with all spatial dimensions compact and of comparable, small size. If the string landscape is dominated by low-dimensional compactifications, cosmic eggs would be natural initial conditions for cosmology. A quantum cosmological treatment of a toy model egg predicts that, in a variant of the Hartle-Hawking state, cosmic eggs break to form higher dimensional universes with a small, but positive cosmological constant or quintessence energy. Hence cosmic egg cosmology yields a scenario in which the seemingly unnaturally small observed value of the vacuum energy can arise from natural initial conditions.
Note:
  • 11 pages, 4 figures, 1 appendix
  • vacuum state: energy
  • quintessence
  • cosmological constant
  • higher-dimensional
  • compactification
  • Kaluza-Klein
  • toy model
  • tunneling
  • string model: landscape
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