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タイトル: | SCREENING OF COSMOLOGICAL CONSTANT IN NON-LOCAL COSMOLOGY |
著者: | ZHANG, YING-LI SASAKI, MISAO |
キーワード: | Non-local gravity cosmological constant problem ghost-free condition power-law solution |
発行日: | Jan-2012 |
出版者: | World Scientific Publishing |
誌名: | International Journal of Modern Physics D |
巻: | 21 |
号: | 01 |
論文番号: | 1250006 |
抄録: | We consider a model of non-local gravity with a large bare cosmological constant, Λ, and study its cosmological solutions. The model is characterized by a function f(ψ) = f0e[αψ], where ψ = □[-1]R and α is a real dimensionless parameter. In the absence of matter, we find an expanding universe solution a ∝ t[n] with n < 1, that is, a universe with decelerated expansion without any fine-tuning of the parameter. Thus the effect of the cosmological constant is effectively shielded in this solution. It has been known that solutions in non-local gravity often suffer from the existence of ghost modes. In the present case, we find the solution is ghost-free if α > α[cr] ≈ 0.17. This is quite a weak condition. We argue that the solution is stable against the inclusion of matter fields. Thus our solution opens up new possibilities for solution to the cosmological constant problem. |
著作権等: | © 2012 World Scientific Publishing Co. この論文は出版社版でありません。引用の際には出版社版をご確認ご利用ください。 This is not the published version. Please cite only the published version. |
URI: | http://hdl.handle.net/2433/154864 |
DOI(出版社版): | 10.1142/S021827181250006X |
出現コレクション: | 学術雑誌掲載論文等 |
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