arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新,休息一下吧,周末愉快~~
arXiv 1009.4436hep-ph
收藏

单圈张量Feynman积分的完全代数约化

A complete algebraic reduction of one-loop tensor Feynman integrals

J. Fleischer, T. Riemann

摘要:

我们建立了一个新的,灵活的方法来减少单圈费曼积分的张量。将秩R=5以下的5点张量积分表示为秩R-1的4点张量积分,从而避免了5点Gram行列式的逆的出现. 4点张量系数用4点积分表示,定义在$d$维数$4-2ε\le d \le 4-2ε+2(R-1)$中,传播子具有更高的幂。它们可以进一步简化为不含逆4点格拉姆行列式的表达式,但包含仅具有标量传播子的一次幂和3点张量系数的高维4点积分。高维四点函数的直接计算将完全避免出现革兰氏行列式的逆幂。然而,最简单的方法是在这里应用维数递归关系,以便将它们减少到通用维数$d = 4-2\eps$中熟悉的2到4点函数,从而引入具有逆4点格拉姆行列式的系数,对于秩为$R$的张量,其幂为$R$。对于小的或消失的革兰氏行列式-在这种减少是不适用的-我们使用的革兰氏行列式的正幂解析展开。改进的收敛性的扩展与Padé逼近,我们接近4点张量系数的评估较大的革兰氏行列式。最后,讨论了费曼图的解析简化中可能用到的一些关系。

英文摘要:

We set up a new, flexible approach for the tensor reduction of one-loop Feynman integrals. The 5-point tensor integrals up to rank R=5 are expressed by 4-point tensor integrals of rank R-1, such that the appearance of the inverse 5-point Gram determinant is avoided. The 4-point tensor coefficients are represented in terms of 4-point integrals, defined in $d$ dimensions, $4-2ε\le d \le 4-2ε+2(R-1)$, with higher powers of the propagators. They can be further reduced to expressions which stay free of the inverse 4-point Gram determinants but contain higher-dimensional 4-point integrals with only the first power of scalar propagators, plus 3-point tensor coefficients. A direct evaluation of the higher dimensional 4-point functions would avoid the appearance of inverse powers of the Gram determinants completely. The simplest approach, however, is to apply here dimensional recurrence relations in order to reduce them to the familiar 2- to 4-point functions in generic dimension $d = 4-2\eps$, introducing thereby coefficients with inverse 4-point Gram determinants up to power $R$ for tensors of rank $R$. For small or vanishing Gram determinants - where this reduction is not applicable - we use analytic expansions in positive powers of the Gram determinants. Improving the convergence of the expansions substantially with Padé approximants we close up to the evaluation of the 4-point tensor coefficients for larger Gram determinants. Finally, some relations are discussed which may be useful for analytic simplifications of Feynman diagrams.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑