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arXiv 1703.01239hep-thhep-ph
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关于$\Box R$ Weyl- Anomaly的流

On the Flow of $\Box R$ Weyl-Anomaly

Vladimir Prochazka, Roman Zwicky

摘要:

外尔异常的一个重要方面是,它们编码的信息的不可逆性的重整化群流。我们认为,$Δ\bar b = \bar{b}^{\textrm{UV}} - \bar{b}^{\textrm{IR}}$,紫外和红外值的差异的$\Box R$项的Weyl异常。这个量与能量动量张量相关器的迹线的四阶矩有关,对于两端共形的理论。微妙之处出现的非共形不动点的情况下,可能是红外不动点与破手征对称。假设矩收敛,则$Δ\bar{b}$通过么正性自动为正。作为一个积分的重正化规模,流量独立性如下,因为它的被积函数是一个总的衍生物。此外,使用动量减法方案(momentum subtraction scheme),4D Zamolodchikov-度规被证明是严格正的,超出了微扰理论,等价于流两端的共形流形的度规。在这个方案中,$\bar{b}(μ)$可以扩展到不动点之外的单调递减函数。四阶矩的紫外线有限性使我们能够定义一个$δ{\cal L} \sim b_0 R^2$项的方案,其中$R^2$异常沿流动消失。在双格式和$R^2$格式中,$\bar{b}(μ)$满足梯度流方程.我们验证了我们的研究结果在自由场理论,高阶导数理论和扩展$Δ\bar{b}$和欧拉流$Δβ_a$的卡斯韦尔银行Zaks不动点的QCD类理论的下一个到下一个领导阶使用最近的$\langle G^2G^2 \rangle$相关计算。

英文摘要:

An important aspect of Weyl anomalies is that they encode information on the irreversibility of the renormalisation group flow. We consider, $Δ\bar b = \bar{b}^{\textrm{UV}} - \bar{b}^{\textrm{IR}}$, the difference of the ultraviolet and infrared value of the $\Box R$-term of the Weyl anomaly. The quantity is related to the fourth moment of the trace of the energy momentum tensor correlator for theories which are conformal at both ends. Subtleties arise for non-conformal fixed points as might be the case for infrared fixed points with broken chiral symmetry. Provided that the moment converges, $Δ\bar{b}$ is then automatically positive by unitarity. Written as an integral over the renormalisation scale, flow-independence follows since its integrand is a total derivative. Furthermore, using a momentum subtraction scheme (MOM) the 4D Zamolodchikov- metric is shown to be strictly positive beyond perturbation theory and equivalent to the metric of a conformal manifold at both ends of the flow. In this scheme $\bar{b}(μ)$ can be extended outside the fixed point to a monotonically decreasing function. The ultraviolet finiteness of the fourth moment enables us to define a scheme for the $δ{\cal L} \sim b_0 R^2$-term, for which the $R^2$-anomaly vanishes along the flow. In the MOM- and the $R^2$-scheme, $\bar{b}(μ)$ is shown to satisfy a gradient flow type equation. We verify our findings in free field theories, higher derivative theories and extend $Δ\bar{b}$ and the Euler flow $Δβ_a$ for a Caswell-Banks-Zaks fixed point for QCD-like theories to next-to-next-to leading order using a recent $\langle G^2G^2 \rangle$-correlator computation.

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