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Quantum gravity corrections to sequestering

对隔离的量子引力修正

基本信息

批准号：
1793013
负责人：
金额：
--
依托单位：
University of Nottingham
依托单位国家：
英国
项目类别：
Studentship
财政年份：
2016
资助国家：
英国
起止时间：
2016 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=studentship-1793013
关键词：
Quantum gravity corrections sequestering

项目摘要

The sequestering proposal is a modification of gravity that provides a partial solution to the cosmological constant problem, inasmuch as it prevents the standard model contributions to vacuum energy from gravitating. Classical sequestering is locally equivalent to classical General Relativity on shell, although globally the theories differ. Nevertheless, Quantum gravity (QG) corrections are expected to break the (local) equivalence between the two. By adopting Donoghue's effective field theory (EFT) approach to QG below some cut-off (usually taken to be the Planck scale) we will study the leading order corrections coming from graviton loops in sequestering. Of course, to test the robustness of the proposal against graviton loops, our main interest lies in the corrections to the relevant operators that dominate the low energy dynamics. Consider, for example, the graviton corrections to the cosmological constant: at one loop we do not expect there to be any such corrections, so we will need to go to two loops for a non-trivial result. We then ask whether or not vacuum loops of gravitons sequester as efficiently as the matter loops. Initially we will ask this in the context of the classical model of sequestering. Naively we do not expect the graviton vacuum energy to cancel as readily as their standard model counterparts. It is important to quantify the size of this effect, and if it is a problem, to get some insight into what is required from a QG improved version of our model. We also need to consider the other leading order low energy QG corrections as these could potentially alter the desired structure of the low energy EFT. This could spoil the cancellation mechanism even in the matter sector, and although such an effect will surely be Planck suppressed, it is imperative we quantify this properly. Furthermore, QG corrections are also expected to alter the local equivalence to GR. This is because the equivalence is only true on shell, and not off shell, so one could imagine loops yielding distinct QG corrections to Newton's law.

隔离方案是对引力的修正，提供了宇宙常数问题的部分解决方案，因为它防止了标准模型对真空能量的贡献受到引力的影响。经典隔离在局部上等同于壳层上的经典广义相对论，尽管在全球范围内这两种理论是不同的。然而，量子引力(QG)修正有望打破两者之间的(局部)等价性。通过采用Donoghue的有效场论(EFT)方法，在一定的截止点(通常为普朗克标度)下，我们将研究闭锁过程中引力子环的主导级次修正。当然，为了测试该提议对引力子环路的稳健性，我们主要感兴趣的是对主导低能动力学的相关算符的修正。例如，考虑引力子对宇宙常数的修正：在一个循环中，我们预计不会有任何这样的修正，所以我们需要去两个循环才能得到一个不平凡的结果。然后我们问，引力子的真空圈是否像物质圈一样有效地隔离。最初，我们将在经典的自动减支模型的背景下提出这个问题。我们天真地认为，引力子真空能量不会像它们的标准模型能量那样容易抵消。重要的是要量化这种影响的大小，如果这是一个问题，就可以深入了解我们的模型的QG改进版本需要什么。我们还需要考虑其他先导阶低能量QG校正，因为这些校正可能会潜在地改变低能量EFT的所需结构。即使是在物质领域，这也可能破坏取消机制，尽管这种影响肯定会被普朗克压制，但我们必须对此进行适当的量化。此外，QG校正也有望改变GR的局部等价性。这是因为等价性只在壳层上是正确的，而不是在壳层下，所以人们可以想象产生对牛顿定律的明显QG修正的环路。