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arXiv 1607.08460hep-thgr-qc
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双曲空间上$f(R)$引力的重整化群方程

Renormalization Group Equation for $f(R)$ gravity on hyperbolic spaces

Kevin Falls, Nobuyoshi Ohta

摘要:

利用度规的指数参数化,我们导出了双曲时空上$f(R)$截断中引力有效平均作用量的流方程。与以往的作品紧凑的空间,我们能够评估轨迹,正是使用优化的截止。这特别揭示了由于拉普拉斯算子的频谱中的间隙,所有模式可以被积分出截止的有限值,从而导致有效作用。研究多项式的解决方案,我们发现较差的收敛性比已经发现紧凑的时空,即使在小曲率的方程只有不同的处理某些模式。在渐近自由不动点附近,我们找到了$R^2$耦合的普适β函数,并计算了相应的涉及$R^2 \log R^2$量子修正的有效作用量.

英文摘要:

We derive the flow equation for the gravitational effective average action in an $f(R)$ truncation on hyperbolic spacetimes using the exponential parametrization of the metric. In contrast to previous works on compact spaces, we are able to evaluate traces exactly using the optimised cutoff. This reveals in particular that all modes can be integrated out for a finite value of the cutoff due to a gap in the spectrum of the Laplacian, leading to the effective action. Studying polynomial solutions, we find poorer convergence than has been found on compact spacetimes even though at small curvature the equations only differ in the treatment of certain modes. In the vicinity of an asymptotically free fixed point, we find the universal beta function for the $R^2$ coupling and compute the corresponding effective action which involves an $R^2 \log R^2$ quantum correction.

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