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arXiv 0906.3477hep-thgr-qchep-ph
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Lifshitz型理论中的重整化群

Renormalization group in Lifshitz-type theories

Roberto Iengo, Jorge G. Russo, Marco Serone

摘要:

本文研究了Lifshitz型标量场理论中耦合的单圈重整化和演化,即在空间和时间上具有不同的标度。这些理论是么正的和可重整化的,这要归功于更高的空间导数项在高能量下修改粒子传播子,但代价是显式破坏洛伦兹对称性。我们研究如果和在什么条件下洛伦兹对称性可以被认为是紧急在低能量通过研究RG演化的"光速“耦合$c^2_ϕ$,并为一个以上的领域,$δc^2\equiv c^2_{ϕ_1}-c^2_{ϕ_2}$在简单的模型。我们发现在紫外光中,$c^2_ϕ$和$δc^2$一般都随能量标度几何地流动。如果$δc^2 \neq 0$在UV中,$c^2$的对数运行也在低能量下持续。因此,洛伦兹对称性不能在低能量下以承受基本实验约束所需的精度恢复,除非所有的洛伦兹破缺项,包括$δc^2$,在紫外线下被不自然地微调到极小的值。我们期望本文的考虑将适用于Lifshitz类型的任何一般理论,包括Horava最近提出的引力量子理论。

英文摘要:

We study the one-loop renormalization and evolution of the couplings in scalar field theories of the Lifshitz type, i.e. with different scaling in space and time. These theories are unitary and renormalizable, thanks to higher spatial derivative terms that modify the particle propagator at high energies, but at the expense of explicitly breaking Lorentz symmetry. We study if and under what conditions the Lorentz symmetry can be considered as emergent at low energies by studying the RG evolution of the ``speed of light'' coupling $c^2_ϕ$ and, for more than one field, of $δc^2\equiv c^2_{ϕ_1}-c^2_{ϕ_2}$ in simple models. We find that in the UV both $c^2_ϕ$ and $δc^2$ generally flow logarithmically with the energy scale. A logarithmic running of $c^2$ persists also at low-energies, if $δc^2 \neq 0$ in the UV. As a result, Lorentz symmetry is not recovered at low energies with the accuracy needed to withstand basic experimental constraints, unless all the Lorentz breaking terms, including $δc^2$, are unnaturally fine-tuned to extremely small values in the UV. We expect that the considerations of this paper will apply to any generic theory of Lifshitz type, including a recently proposed quantum theory of gravity by Horava.

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