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arXiv 1201.4170hep-thhep-ph
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N=4 SYM中的分析双环路形状因子

Analytic two-loop form factors in N=4 SYM

Andreas Brandhuber, Gabriele Travaglini, Gang Yang

摘要:

本文给出了N=4超Yang-Mills中半BPS算子在两个环上的三点MHV形状因子的紧表达式。我们计算的主要工具是应用于形状因子水平的广义么正性,以及超对称树级形状因子和进入切割的振幅的紧凑表达式。我们证实,红外发散指数预期,共线分解是完全捕获的ABDK/BDS的分析。接下来,我们构造通过从完整的双回路形状因子中减去该系数而获得的双回路剩余函数,并对其进行数值计算。使用符号学,结合各种物理约束和对称性,我们找到了一个独特的解决方案,其符号。有了这个输入,我们构建了一个非常紧凑的解析表达式的剩余功能,其中只包含经典的多项式,并比较我们的数值结果。此外,我们令人惊讶的观察到,我们的余数等于QCD中密切相关的双环振幅的最大超越部分。

英文摘要:

We derive a compact expression for the three-point MHV form factors of half-BPS operators in N=4 super Yang-Mills at two loops. The main tools of our calculation are generalised unitarity applied at the form factor level, and the compact expressions for supersymmetric tree-level form factors and amplitudes entering the cuts. We confirm that infrared divergences exponentiate as expected, and that collinear factorisation is entirely captured by an ABDK/BDS ansatz. Next, we construct the two-loop remainder function obtained by subtracting this ansatz from the full two-loop form factor and compute it numerically. Using symbology, combined with various physical constraints and symmetries, we find a unique solution for its symbol. With this input we construct a remarkably compact analytic expression for the remainder function, which contains only classical polylogarithms, and compare it to our numerical results. Furthermore, we make the surprising observation that our remainder is equal to the maximally transcendental piece of a closely related two-loop amplitude in QCD.

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。

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