Université Paris Diderot Paris 7, Laboratoire APC, Bâtiment Condorcet, Case 7020, 75205 Paris Cedex 13, France.
Phys Rev Lett. 2011 Jul 8;107(2):021101. doi: 10.1103/PhysRevLett.107.021101. Epub 2011 Jul 6.
We study the infrared (long-distance) behavior of the free photon field in de Sitter spacetime. Using a two-parameter family of gauge-fixing terms, we show that the infrared (IR) behavior of the two-point function is highly gauge-dependent and ranges from vanishing to growing. This situation is in disagreement with its counterpart in flat spacetime, where the two-point function vanishes in the IR region for any choice of the gauge-fixing parameters. A criterion to isolate the physical part of the two-point function is given and is shown to lead to a well-behaved two-point function in the IR region.
我们研究了德西特时空中自由光子场的红外（远距离）行为。使用一族带有两个参数的规范固定项，我们表明，两点函数的红外（IR）行为高度依赖于规范，范围从消失到增长。这种情况与平坦时空中的对应情况不同，在平坦时空中，无论规范固定参数如何选择，两点函数在红外区域都为零。我们给出了一个分离两点函数物理部分的准则，并表明该准则在红外区域会导致两点函数表现良好。
