The primordial curvature perturbation from vector fields of general non-Abelian groups
The primordial curvature perturbation from vector fields of general non-Abelian groups
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一般非阿贝尔群矢量场的原初曲率摄动
DOI：
10.1088/1475-7516/2012/01/014
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发表时间：
2011
影响因子：
6.4
通讯作者：
Mindaugas Karčiauskas
中科院分区：
文献类型：
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作者：
Mindaugas Karčiauskas
本文研究了一般非阿贝尔向量场的原曲率扰动的生成问题。非阿贝尔场的自相互作用使场的扰动非高斯。我们计算的双谱的场微扰使用在形式主义在树的水平。双谱由视界外场的经典演化控制。鉴于此，我们证明了主要贡献可以从齐次经典运动方程中获得。然后我们计算了曲率扰动的功率谱。谱的各向异性被场的数目所抑制。这使得矢量场有可能对宇宙中的总曲率扰动负责，而不会违反统计各向异性的观测界限。曲率扰动的双谱也是各向异性的。最后，我们给出了一个例子的通货膨胀结束的情况下，曲率扰动产生的矢量规范场通过变化的规范耦合常数（s），这在协变导数耦合希格斯场的矢量场。我们发现，适当大的规范群可能会导致可观察到的各向异性的曲率扰动的功率谱。
We consider the generation of primordial curvature perturbation by general non-Abelian vector fields without committing to a particular group. Self-interactions of non-Abelian fields make the field perturbation non-Gaussian. We calculate the bispectrum of the field perturbation using the in-in formalism at tree level. The bispectrum is dominated by the classical evolution of fields outside the horizon. In view of this we show that the dominant contribution can be obtained from the homogeneous classical equation of motion. Then we calculate the power spectrum of the curvature perturbation. The anisotropy in spectrum is suppressed by the number of fields. This makes it possible for vector fields to be responsible for the total curvature perturbation in the Universe without violating observational bounds on statistical anisotropy. The bispectrum of the curvature perturbation is also anisotropic. Finally we give an example of the end-of-inflation scenario in which the curvature perturbation is generated by vector gauge fields through varying gauge coupling constant(s), which in covariant derivatives couples the Higgs field to the vector fields. We find that reasonably large gauge groups may result in the observable anisotropy in the power spectrum of the curvature perturbation.