论文标题
原始引力波的传播速度
Propagating Speed of Primordial Gravitational Waves
论文作者
论文摘要
原始引力波，即，如果测量量子通货膨胀波动产生的度量扰动背景，则可以为原始通货膨胀提供了充分的证据，并在极高的能量尺度下阐明了物理学。在这项工作中，我们专注于它们的传播速度。使用有效的现场理论方法，我们介绍了一个与时间有关的传播速度$ c _ {\ rm t}（t）$，表明与一般相对性（GR）预测$ c _ {\ rm t}（t）= c $也可以导致可检测的后果。我们得出了一组将传播速度及其时间依赖性与通货膨胀参数相关联的方程组，并概括了通常的慢速滚动一致性关系。施加了新的广义一致性关系并结合了大小规模数据，我们以非平凡的原始张量速度对通货膨胀产生了独立的限制。特别是，我们将其比例依赖性限制为$ d \ log c _ {\ rm t} / d \ log k = 0.082^{+0.047} _ { - 0.11} $ 68％c.l。虽然我们仅得出下限的$ c _ {\ rm t}> 0.22 \，c $ 95％c.l. 。我们还以枢轴比例$ k _*= 0.05 \ rm {mpc}^{ - 1} $限制了张量与量表的比例，为$ r <0.0599 $ <0.0599 $ 95％c.l.与普朗克合作提供的结果一致。多亏了张量光谱的适当小规模参数化，我们在张量倾斜$ n _ {\ rm t} = -0.084^{+0.10} _ { - 0.047} $ 68％c.l.上得出了严格的约束。并且在其运行中$α_ {\ rm t} = d \，n _ {\ rm t}/d \ log k = 0.0141^{+0.0035} _ { - 0.021} $和$β_ {\ rm t} -0.0061^{+0.010} _ { - 0.0014} $均为68％c.l.我们的结果表明，与标准慢速预测相当一致，并证明当前数据可以显着限制与通货膨胀能量尺度上GR的偏差。
Primordial Gravitational Waves, i.e. a background of metric perturbations sourced by the quantum inflationary fluctuations, if measured, could both provide a substantial evidence for primordial inflation and shed light on physics at extremely high energy scales. In this work we focus on their propagating speed. Using an effective field theory approach we introduce a time-dependent propagating speed $c_{\rm T}(t)$ showing that also small deviations from the General Relativity (GR) prediction $c_{\rm T}(t) = c$ can lead to testable consequences. We derive a set of equations that relate the propagating speed and its time dependence to the inflationary parameters and that generalize the usual slow roll consistency relations. Imposing the new generalized consistency relations and combining small and large scales data, we derive model independent constraints on inflation with non-trivial primordial tensor speed. In particular we constrain its scale dependence to be $d\log c_{\rm T} / d\log k=0.082^{+0.047}_{-0.11}$ at 68% C.L. while we only derive the lower bound $c_{\rm T}>0.22\,c$ at 95% C.L. . We also constrain the tensor-to-scalar ratio at the pivot scale $k_*=0.05\rm{Mpc}^{-1}$ to be $r<0.0599$ at 95% C.L. in agreement with the result provided by the Planck collaboration. Thanks to a proper small scale parameterization of the tensor spectrum we derive stringent constraints on the tensor tilt $n_{\rm T}=-0.084^{+0.10}_{-0.047}$ at 68% C.L. and on its runnings $α_{\rm T}=d\,n_{\rm T}/d\log k=0.0141^{+0.0035}_{-0.021}$ and $β_{\rm T}=d\,α_{\rm T}/d\log k= -0.0061^{+0.010}_{-0.0014}$ both at 68% C.L. Our results show a remarkable agreement with the standard slow roll predictions and prove that current data can significantly constrain deviations from GR on the inflationary energy scales.
