超静态时空中修正色散格林函数的动量空间表示
A momentum-space representation of Green's functions with modified dispersion on ultra-static space-time
摘要：
本文研究了在弯曲超静背景上传播的标量场在修正色散关系下的格林函数。由于Klein-Gordon算子中的高阶空间导数，通常的适当时间deWitt-Schwinger方法来获得格林函数的级数表示注定要失败。我们将展示如何克服这一困难，考虑一个首选的帧，与一个单位时间的向量。对于这个坐标系，我们可以将格林函数表示为空间相关函数在所有频率上的积分。后者可以在动量空间中展开，作为具有类似于deWitt-Schwinger的几何系数的级数。通过在所有频率上积分，我们最终找到了格林函数的扩展，直到度量张量的四个导数。与适当的时间形式主义的关系也进行了讨论。
英文摘要：
We consider the Green's functions associated to a scalar field propagating on a curved, ultra-static background, in the presence of modified dispersion relations. The usual proper-time deWitt-Schwinger procedure to obtain a series representation of the Green's functions is doomed to failure, because of higher order spatial derivatives in the Klein-Gordon operator. We show how to overcome this difficulty by considering a preferred frame, associated to a unit time-like vector. With respect to this frame, we can express the Green's functions as an integral over all frequencies of a space-dependent function. The latter can be expanded in momentum space, as a series with geometric coefficients similar to the deWitt-Schwinger's ones. By integrating over all frequencies, we finally find the expansion of the Green's function up to four derivatives of the metric tensor. The relation with the proper-time formalism is also discussed.
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