arXiv 1404.48832014-04hep-thastro-ph.COgr-qchep-ph

阿贝尔对称破缺的一个小宇宙学常数

A small cosmological constant from Abelian symmetry breaking

Gianmassimo Tasinato

备注：: 14 pages, no figures. V2: Added references and a section discussing coupling with matter. Published version
发表信息：: Class. Quant. Grav. 31 (2014) 225004
DOI：: 10.1088/0264-9381/31/22/225004

摘要：

我们调查的一些宇宙学后果的矢量张量理论的阿贝尔对称性在矢量部门略有打破的质量项和鬼自由衍生自相互作用。当我们研究大的裸宇宙学常数$Λ_{cc}$存在时的宇宙膨胀时，我们发现该理论允许de Sitter解的分支，其中哈勃参数的尺度与$Λ_{cc}$的幂成反比。因此，$Λ_{cc}$的大值导致哈勃尺度的小尺寸。在一个适当的限制，其中对称性破缺参数是小的，该理论恢复阿贝尔对称性加上额外的伽利略对称性作用于纵向矢量极化。近似的伽利略对称性可以使这个理论的结构在我们感兴趣的能量尺度上稳定。我们还分析了de Sitter解周围的线性宇宙学涨落的动力学，表明没有明显的不稳定性出现，并且横向矢量极化在这些配置周围变得无质量。

英文摘要：

We investigate some cosmological consequences of a vector-tensor theory where an Abelian symmetry in the vector sector is slightly broken by a mass term and by ghost-free derivative self-interactions. When studying cosmological expansion in the presence of large bare cosmological constant $Λ_{cc}$, we find that the theory admits branches of de Sitter solutions in which the scale of the Hubble parameter is inversely proportional to a power of $Λ_{cc}$. Hence, a large value of $Λ_{cc}$ leads to a small size for the Hubble scale. In an appropriate limit, in which the symmetry breaking parameters are small, the theory recovers the Abelian symmetry plus an additional Galileon symmetry acting on the longitudinal vector polarization. The approximate Galileon symmetry can make the structure of this theory stable at the energy scales we are interested in. We also analyze the dynamics of linearized cosmological fluctuations around the de Sitter solutions, showing that no manifest instabilities arise, and that the transverse vector polarizations become massless around these configurations.

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