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arXiv 1104.1392hep-thgr-qchep-ph
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广义相对论的标度不变替代

Scale-invariant alternatives to general relativity

Diego Blas, Mikhail Shaposhnikov, Daniel Zenhausern

摘要:

我们研究了基于标度不变性(因此不存在任何质量参数)和横向同形不变性(TDiff)的一般引力场理论,TDiff是4-体积守恒坐标变换。我们表明,这些理论是等价于一个特定类型的标量张量理论的重力(不变下的所有同态)与一些属性,使他们的现象学有趣。它们包含,除了原理论的无量纲耦合常数,一个任意的量纲参数$Λ_0$。这个参数与运动方程的积分常数有关,类似于出现在单模引力中的任意宇宙学常数。我们专注于牛顿常数和电弱标度出现的自发打破标度不变性和无关的$Λ_0$的理论。这些理论的无质量粒子谱包含引力子和一种新的粒子-引力子。对于$Λ_0=0$,无质量介子与物质场只有导数耦合,并且很容易满足第五种力存在的界限。至于物质场,我们确定的条件导致一个可重整化的低能理论。如果是$Λ_0\neq 0$,则标度不变性被破坏。任意常数$Λ_0$产生一个"逃逸"电势。因此,光子可以作为动态的暗能量成分。我们阐明了所考虑的理论类别中宇宙学常数的起源,并制定了导致其不存在的条件。如果满足这个条件,那么暗能量就是纯粹的动力学的,并且与暗子相关联。

英文摘要:

We study the general class of gravitational field theories constructed on the basis of scale invariance (and therefore absence of any mass parameters) and invariance under transverse diffeomorphisms (TDiff), which are the 4-volume conserving coordinate transformations. We show that these theories are equivalent to a specific type of scalar-tensor theories of gravity (invariant under all diffeomorphisms) with a number of properties, making them phenomenologically interesting. They contain, in addition to the dimensionless coupling constants of the original theory, an arbitrary dimensionful parameter $Λ_0$. This parameter is associated with an integration constant of the equations of motion, similar to the arbitrary cosmological constant appearing in unimodular gravity. We focus on the theories where Newton's constant and the electroweak scale emerge from the spontaneous breaking of scale invariance and are unrelated to $Λ_0$. The massless particle spectrum of these theories contains the graviton and a new particle -- dilaton. For $Λ_0=0$, the massless dilaton has only derivative couplings to matter fields and the bounds on the existence of a 5th force are easily satisfied. As for the matter fields, we determine the conditions leading to a renormalizable low-energy theory. If $Λ_0\neq 0$, scale invariance is broken. The arbitrary constant $Λ_0$ produces a "run-away" potential for the dilaton. As a consequence, the dilaton can act as a dynamical dark energy component. We elucidate the origin of the cosmological constant in the class of theories under consideration and formulate the condition leading to its absence. If this condition is satisfied, dark energy is purely dynamical and associated to the dilaton.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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