期刊
PHYSICAL REVIEW LETTERS
卷 113, 期 25, 页码 -出版社
AMER PHYSICAL SOC
DOI: 10.1103/PhysRevLett.113.251302
关键词
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资金
- NSF [PHY-1066293]
- JHU of NSF [0244990]
- John Templeton Foundation
- Simons Foundation
- Austrian Academy of Sciences
- Ford Foundation via the National Academies of the Sciences
- U.S. Department of Energy [DE-ACO2-76SF00515]
- Direct For Mathematical & Physical Scien
- Division Of Physics [1214000] Funding Source: National Science Foundation
String theories suggest the existence of a plethora of axionlike fields with masses spread over a huge number of decades. Here, we show that these ideas lend themselves to a model of quintessence with no super-Planckian field excursions and in which all dimensionless numbers are order unity. The scenario addresses the Why now? problem-i.e., Why has accelerated expansion begun only recently?-by suggesting that the onset of dark-energy domination occurs randomly with a slowly decreasing probability per unit logarithmic interval in cosmic time. The standard axion potential requires us to postulate a rapid decay of most of the axion fields that do not become dark energy. The need for these decays is averted, though, with the introduction of a slightly modified axion potential. In either case, a universe like ours arises in roughly 1 in 100 universes. The scenario may have a host of observable consequences.
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