标题： CMB功率谱中重物理的特征 显示英文标题

标题： Features of heavy physics in the CMB power spectrum

摘要： 多场暴胀模型中原始功率谱的计算要求我们正确地考虑视界内外绝热模式和非绝热模式之间的一切相关相互作用。 一个特定的复杂性来源于由暴胀子在多维场空间中的曲率轨迹诱导的导数相互作用。 在这项工作中，我们计算了通用多场模型中的功率谱，并表明某些暴胀子轨迹可能导致原始功率谱中出现可观察到的重要印记，即“重”物理的影响，如果暴胀子轨迹足够快地转弯（即穿过弯曲），即使在正常模态的质量接近我们理论的截止值的情况下也是如此。 我们强调，转弯是相对于西格玛模型度规的测地线定义的，无论这是否是规范的或非平凡的。 这些印记通常表现为功率谱上的阻尼叠加振荡。 在两场模型的特殊情况下，如果其中一个场相对于暴胀尺度足够大，则我们可以计算出绝热模式的有效低能理论，其中包含了全多场动力学的一些相关算符。 正如预期的那样，这种有效理论的一个特征是对绝热模式的速度进行了修改，该速度是背景暴胀子轨迹和暴胀期间经历的转弯的泛函。 因此，我们还期望与功率谱中留下的特征直接相关的非高斯信号。 显示英文摘要

摘要： The computation of the primordial power spectrum in multi-field inflation models requires us to correctly account for all relevant interactions between adiabatic and non-adiabatic modes around and after horizon crossing. One specific complication arises from derivative interactions induced by the curvilinear trajectory of the inflaton in a multi-dimensional field space. In this work we compute the power spectrum in general multi-field models and show that certain inflaton trajectories may lead to observationally significant imprints of `heavy' physics in the primordial power spectrum if the inflaton trajectory turns, that is, traverses a bend, sufficiently fast (without interrupting slow roll), even in cases where the normal modes have masses approaching the cutoff of our theory. We emphasise that turning is defined with respect to the geodesics of the sigma model metric, irrespective of whether this is canonical or non-trivial. The imprints generically take the form of damped superimposed oscillations on the power spectrum. In the particular case of two-field models, if one of the fields is sufficiently massive compared to the scale of inflation, we are able to compute an effective low energy theory for the adiabatic mode encapsulating certain relevant operators of the full multi-field dynamics. As expected, a particular characteristic of this effective theory is a modified speed of sound for the adiabatic mode which is a functional of the background inflaton trajectory and the turns traversed during inflation. Hence in addition, we expect non-Gaussian signatures directly related to the features imprinted in the power spectrum.