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arXiv 2005.11846hep-thmath-phmath.MP
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随机张量模型重整化群流局部截断的可靠性

Reliability of the local truncations for the random tensor models renormalization group flow

Vincent Lahoche, Dine Ousmane Samary

摘要:

张量模型的重整化群的标准非微扰方法通常只考虑局部势近似(即只涉及广义迹及其乘积),并严重违反了修正的沃德恒等式.本文作为我们最近的贡献[Physical Review D 101,106015(2020)]的继续,旨在研究在大$N$极限下,$2n$ -点观测量之间与沃德恒等式和约束相容的近似方案。我们分别考虑两种不同的近似:在第一个,我们试图构建一个本地潜在的近似从一个轻微的修改的Litim调节器,使其保持最佳的在通常意义上,并保留在深紫外和深红外限制的边界条件。在第二个中,我们引入衍生耦合截断和表明,与沃德恒等式的兼容性意味着强大的$β$ -功能之间的关系,允许关闭的无限层次的流方程的非分支部门,直到一个给定的顺序在衍生扩展。最后,使用大$N$ -极限的相关函数之间的精确关系,我们表明,严格的本地截断是不够的,以达到临界指数的精确值,突出这些强关系的可观的考虑到流的行为所发挥的作用;和多迹运营商所发挥的作用,讨论了两种不同的近似方案。在这两种情况下,我们比较我们的结论,在文献中得到的结果,并得出结论,在给定的顺序,考虑到像沃德恒等式在一个系统的方式,我们可以大大提高精确RG方程的近似的物理相关性的观测量之间的确切的功能关系。

英文摘要:

The standard nonperturbative approaches of renormalization group for tensor models are generally focused on a purely local potential approximation (i.e. involving only generalized traces and product of them) and are showed to strongly violate the modified Ward identities. This paper as a continuation of our recent contribution [Physical Review D 101, 106015 (2020)], intended to investigate the approximation schemes compatibles with Ward identities and constraints between $2n$-points observables in the large $N$-limit. We consider separately two different approximations: In the first one, we try to construct a local potential approximation from a slight modification of the Litim regulator, so that it remains optimal in the usual sense, and preserves the boundary conditions in deep UV and deep IR limits. In the second one, we introduce derivative couplings in the truncations and show that the compatibility with Ward identities implies strong relations between $β$-functions, allowing to close the infinite hierarchy of flow equations in the non-branching sector, up to a given order in the derivative expansion. Finally, using exact relation between correlations functions in large $N$-limit, we show that strictly local truncations are insufficient to reach the exact value for the critical exponent, highlighting the role played by these strong relations between observables taking into account the behavior of the flow; and the role played by the multi-trace operators, discussed in the two different approximation schemes. In both cases, we compare our conclusions to the results obtained in the literature and conclude that, at a given order, taking into account the exact functional relations between observables like Ward identities in a systematic way we can strongly improve the physical relevance of the approximation for exact RG equation.

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