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arXiv 2209.01079hep-thgr-qc
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带电标量场的绝热展开与Hadamard重整化的等价性

Equivalence of the adiabatic expansion and Hadamard renormalization for a charged scalar field

Silvia Pla, Elizabeth Winstanley

AI总结:

本文研究带电标量场在FLRW宇宙中三种重整化方法的关系,证明DeWitt-Schwinger表示是Hadamard表示的特例,并在偶数维时空中证明DeWitt-Schwinger展开与绝热展开等价,而奇数维情形仍需进一步研究。

摘要:

我们考察了作用于带电量子标量场的场算符期望值重整化的三种方法(Hadamard、DeWitt-Schwinger和绝热方法)之间的关系。首先,我们证明Feynman Green函数的DeWitt-Schwinger表示是Hadamard表示的一个特例。接着,我们将注意力限制在空间平坦的Friedmann-Lemaitre-Robertson-Walker宇宙中,背景电磁场为纯电场且随时间变化,考虑二维、三维和四维时空。在达到应力-能量张量(SET)重整化所需的阶数下,我们求出了时空点空间分离时Green函数的绝热展开和DeWitt-Schwinger展开。在二维和四维中,所得的DeWitt-Schwinger展开与绝热展开完全相同。在三维中,DeWitt-Schwinger展开包含绝热四阶项,这些项对于SET的重整化并非必要,因此在绝热展开中不存在。由此证明了在所考虑的情形下,DeWitt-Schwinger方法与绝热方法在偶数维中对于重整化是等价的。在奇数维中情况尚不明确,需要进一步研究以确定绝热重整化是否是一种局域协变的重整化方案。

英文摘要:

We examine the relationship between three approaches (Hadamard, DeWitt-Schwinger and adiabatic) to the renormalization of expectation values of field operators acting on a charged quantum scalar field. First, we demonstrate that the DeWitt-Schwinger representation of the Feynman Green's function is a particular case of the Hadamard representation. Next, we restrict attention to a spatially flat Friedmann-Lemaitre-Robertson-Walker universe with time-dependent, purely electric, background electromagnetic field, considering two, three and four-dimensional space-times. Working to the order required for the renormalization of the stress-energy tensor (SET), we find the adiabatic and DeWitt-Schwinger expansions of the Green's function when the space-time points are spatially separated. In two and four dimensions, the resulting DeWitt-Schwinger and adiabatic expansions are identical. In three dimensions, the DeWitt-Schwinger expansion contains terms of adiabatic order four which are not necessary for the renormalization of the SET and hence absent in the adiabatic expansion. The equivalence of the DeWitt-Schwinger and adiabatic approaches to renormalization in the scenario considered is thereby demonstrated in even dimensions. In odd dimensions the situation is less clear and further investigation is required in order to determine whether adiabatic renormalization is a locally covariant renormalization prescription.

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