Generalized unitarity and one-loop amplitudes in N=4 super-Yang-Mills
Generalized unitarity and one-loop amplitudes in N=4 super-Yang-Mills
复制标题
DOI：
10.1016/j.nuclphysb.2005.07.014
复制
发表时间：
2004-12
期刊：
影响因子：
--
通讯作者：
R. Britto;F. Cachazo;Bo Feng
中科院分区：
文献类型：
--
作者：
R. Britto;F. Cachazo;Bo Feng
N=4 规范理论中胶子的单环振幅可以写成已知标量箱积分与有理函数系数的线性组合。在本文中，我们展示了如何使用广义幺正性来基本上读取系数。我们使用的广义酉割是四重割。这些可以直接应用于四质量标量积分系数的计算，并且我们明确地以次一级 MHV 振幅呈现结果。对于具有至少一个无质量外腿的标量盒函数，我们表明，通过在签名 (−−++) 中进行计算，也可以从四次切割中获得系数，这在 Minkowski 签名中没有用处。作为示例，我们重现了 MHV 振幅附近的七胶子的一些一质量、二质量和三质量标量盒积分的系数，并且计算了所有多重性的 MHV 振幅附近的几类三质量和两质量硬系数。
One-loop amplitudes of gluons in N=4 gauge theory can be written as linear combinations of known scalar box integrals with coefficients that are rational functions. In this paper we show how to use generalized unitarity to basically read off the coefficients. The generalized unitarity cuts we use are quadruple cuts. These can be directly applied to the computation of four-mass scalar integral coefficients, and we explicitly present results in next-to-next-to-MHV amplitudes. For scalar box functions with at least one massless external leg we show that by doing the computation in signature (−−++) the coefficients can also be obtained from quadruple cuts, which are not useful in Minkowski signature. As examples, we reproduce the coefficients of some one-, two-, and three-mass scalar box integrals of the seven-gluon next-to-MHV amplitude, and we compute several classes of three-mass and two-mass-hard coefficients of next-to-MHV amplitudes to all multiplicities.