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arXiv 2008.05346hep-thhep-ph
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能量动量张量的两点函数与广义共形结构

Two-point function of the energy-momentum tensor and generalised conformal structure

Claudio Corianò, Luigi Delle Rose, Kostas Skenderis

摘要:

具有广义共形结构的理论包含一个量纲参数,它在作用中表现为一个整体的乘法因子。这种理论的例子是规范理论耦合到无质量标量和费米子与汤川相互作用和四次耦合的标量在时空维度以外。这种理论的许多性质与共形场论(CFT)相似,特别是它们的两点函数与CFT的形式相同,但归一化常数现在被有效无量纲耦合$g$的函数所取代,该有效无量纲耦合是由量纲参数和两个算子之间的距离构造的。这样的理论出现在涉及非共形膜的全息对偶中,并且在强耦合下已经观察到了这种行为。在这里,我们提出了一个微扰计算的两点函数的能量动量张量的两个循环的尺寸$d= 3, 5$,确认预期的结构和确定相应的功能$g$这个顺序,包括重整化的影响。我们还讨论了d=4的情况进行比较。$d=3$的结果是相关的全息宇宙学,在这种情况下,我们还研究了一个$Φ^6$耦合,而边际在通常意义上是无关紧要的广义共形结构的角度。事实上,这种耦合在2点函数中的效果在IR中被洗掉,但它修改了UV。

英文摘要:

Theories with generalised conformal structure contain a dimensionful parameter, which appears as an overall multiplicative factor in the action. Examples of such theories are gauge theories coupled to massless scalars and fermions with Yukawa interactions and quartic couplings for the scalars in spacetime dimensions other than 4. Many properties of such theories are similar to that of conformal field theories (CFT), and in particular their 2-point functions take the same form as in CFT but with the normalisation constant now replaced by a function of the effective dimensionless coupling $g$ constructed from the dimensionful parameter and the distance separating the two operators. Such theories appear in holographic dualities involving non-conformal branes and this behaviour of the correlators has already been observed at strong coupling. Here we present a perturbative computation of the two-point function of the energy-momentum tensor to two loops in dimensions $d= 3, 5$, confirming the expected structure and determining the corresponding functions of $g$ to this order, including the effects of renormalisation. We also discuss the d=4 case for comparison. The results for $d=3$ are relevant for holographic cosmology, and in this case we also study the effect of a $Φ^6$ coupling, which while marginal in the usual sense it is irrelevant from the perspective of the generalised conformal structure. Indeed, the effect of such coupling in the 2-point function is washed out in the IR but it modifies the UV.

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