Bimetric gravity is cosmologically viable
Bimetric gravity is cosmologically viable
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DOI：
10.1016/j.physletb.2015.06.062
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发表时间：
2015-09-02
影响因子：
4.4
通讯作者：
Solomon, Adam R.
中科院分区：
文献类型：
--
作者：
Akrami, Yashar;Hassan, S. F.;Solomon, Adam R.
双尺度理论描述了存在额外的自旋2场时的引力相互作用。以前的工作表明，它的宇宙学解决方案普遍受到不稳定因素的困扰。我们表明，通过将普朗克质量作为第二度规，M-f很小，这些不稳定性可以被推回到不可察觉的早期。在这个极限下，该理论用一个有效的宇宙学常数来接近广义相对论，而这个有效的宇宙学常数是由自旋-2相互作用尺度决定的。这提供了一个非常接近Lambda CDM的后期膨胀历史，但具有技术上的自然宇宙常数价值。我们发现，M-f不应大于电弱标度，才能使宇宙微扰通过大爆炸核合成保持稳定。我们进一步表明，在这个极限下，螺旋度-0模在低能标度下不再是强耦合的。(C)2015年提交人。爱思唯尔出版公司(Elsevier B.V.)
Bimetric theory describes gravitational interactions in the presence of an extra spin-2 field. Previous work has suggested that its cosmological solutions are generically plagued by instabilities. We show that by taking the Planck mass for the second metric, M-f, to be small, these instabilities can be pushed back to unobservably early times. In this limit, the theory approaches general relativity with an effective cosmological constant which is, remarkably, determined by the spin-2 interaction scale. This provides a late-time expansion history which is extremely close to Lambda CDM, but with a technically-natural value for the cosmological constant. We find M-f should be no larger than the electroweak scale in order for cosmological perturbations to be stable by big-bang nucleosynthesis. We further show that in this limit the helicity-0 mode is no longer strongly-coupled at low energy scales. (C) 2015 The Authors. Published by Elsevier B.V.