探测宇宙学中的洛伦兹破坏场
Detecting a Lorentz-Violating Field in Cosmology
摘要：
我们考虑爱因斯坦-以太理论（耦合到动态类时洛伦兹破坏矢量场的引力的一般协变理论）中的宇宙学与线性以太-拉格朗日。利用3+1时空分裂方法导出了适用于一般拉格朗日量的协变和规范不变微扰方程。限制注意这些理论的参数空间，这是符合当地的引力实验，我们表明，有以太场的跟踪行为，无论是在背景宇宙学和线性微扰水平。在这个模型中的标量微扰的原始功率谱被证明是相同的预测标准广义相对论。然而，张量扰动的功率谱与广义相对论中的功率谱不同，只是幅度较小，目前还不能探测到。我们还研究了它对后期宇宙学的意义，发现在辐射和物质主导的时期，光子和中微子各向异性应力的演化可以引起以太场的扰动，从而修正了CMB和物质的功率谱。然而，这些效应相对于其他宇宙学参数，如中微子质量和观测到的星系光谱中的偏置参数是简并的。
英文摘要：
We consider cosmology in the Einstein-aether theory (the generally covariant theory of gravitation coupled to a dynamical timelike Lorentz-violating vector field) with a linear aether-Lagrangian. The 3+1 spacetime splitting approach is used to derive covariant and gauge invariant perturbation equations which are valid for a general class of Lagrangians. Restricting attention to the parameter space of these theories which is consistent with local gravity experiments, we show that there are tracking behaviors for the aether field, both in the background cosmology and at linear perturbation level. The primordial power-spectrum of scalar perturbations in this model is shown to be the same that predicted by standard general relativity. However, the power-spectrum of tensor perturbation is different from that in general relativity, but has a smaller amplitude and so cannot be detected at present. We also study the implications for late-time cosmology and find that the evolution of photon and neutrino anisotropic stresses can source the aether field perturbation during the radiation and matter dominated epochs, and as a result the CMB and matter power spectra are modified. However these effects are degenerate with respect to other cosmological parameters, such as neutrino masses and the bias parameter in the observed galaxy spectrum.
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