摘要翻译：
在小温度展开下，计算了三角形晶格上具有O(N)不变性的sigma模型在N=-1处的二圈重整化常数和第一非普适项β函数的三圈系数。对于负温度，相应的Grassmann理论的配分函数是这样一个格子上无根森林的母函数，其中温度作为森林中树木数量的化学势。为了计算Feynman图，我们将坐标空间方法推广到三角形格子。
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英文标题：
《Renormalization flow for unrooted forests on a triangular lattice》
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作者：
Sergio Caracciolo (Milan U. & INFN, Milan), Claudia De Grandi (Boston
  U.), Andrea Sportiello (Milan U. & INFN, Milan)
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最新提交年份：
2007
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分类信息：

一级分类：Physics        物理学
二级分类：Statistical Mechanics        统计力学
分类描述：Phase transitions, thermodynamics, field theory, non-equilibrium phenomena, renormalization group and scaling, integrable models, turbulence
相变，热力学，场论，非平衡现象，重整化群和标度，可积模型，湍流
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一级分类：Physics        物理学
二级分类：High Energy Physics - Lattice        高能物理-晶格
分类描述：Lattice field theory. Phenomenology from lattice field theory. Algorithms for lattice field theory.  Hardware for lattice field theory.
晶格场论。从晶格场论到现象学。格场论的算法。晶格场论硬件。
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英文摘要：
  We compute in small temperature expansion the two-loop renormalization constants and the three-loop coefficient of the beta-function, that is the first non-universal term, for the sigma-model with O(N) invariance on the triangular lattice at N=-1. The partition function of the corresponding Grassmann theory is, for negative temperature, the generating function of unrooted forests on such a lattice, where the temperature acts as a chemical potential for the number of trees in the forest. To evaluate Feynman diagrams we extend the coordinate space method to the triangular lattice.
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PDF链接：
https://arxiv.org/pdf/705.3891