Combinatorics in tensor-integral reduction. (16th January 2017)

• Record Type: Journal Article
• Authors: Ee, June-Haak; Jung, Dong-Won; Kim, U-Rae; Lee, Jungil
• Is Part Of: European journal of physics. Volume 38:Number 2(2017:Mar.)
• Publication Date: 2017-01-16
• Subjects: combinatorics -- tensor angular integral -- tensor-integral reduction -- isotropic tensor -- Feynman integral; Physics -- Periodicals; Physics -- Study and teaching (Higher) -- Europe -- Periodicals; 530
• DOI: 10.1088/1361-6404/aa54ce
• Languages: English
• ISSNs: 0143-0807

Abstract

Abstract: We illustrate a rigorous approach to express the totally symmetric isotropic tensors of arbitrary rank in the n -dimensional Euclidean space as a linear combination of products of Kronecker deltas. By making full use of the symmetries, one can greatly reduce the efforts to compute cumbersome angular integrals into straightforward combinatoric counts. This method is generalised into the cases in which such symmetries are present in subspaces. We further demonstrate the mechanism of the tensor-integral reduction that is widely used in various physics problems such as perturbative calculations of the gauge-field theory in which divergent integrals are regularised in d = 4 − 2 ϵ space–time dimensions. The main derivation is given in the n -dimensional Euclidean space. The generalisation of the result to the Minkowski space is also discussed in order to provide graduate students and researchers with techniques of tensor-integral reduction for particle physics problems.