论文标题
QED和QCD螺旋幅度在Parton-Shower仪表中
QED and QCD helicity amplitudes in parton-shower gauge
论文作者
论文摘要
我们介绍了光子和Gluon繁殖器，其中通过利用从物理上壳状状态产生的非壳矢量玻色子的BRST不变性来系统地减去标量极化成分。繁殖器具有轻度仪表形式，仪表矢量的空间分量沿离壳载体玻色子动量的负数指向。我们将量规称为parton-shower仪表，因为在共线构型中，每个feynman振幅的绝对值平方均重现了该仪表中相应的parton淋浴的所有奇异行为。我们引入了新的HELAS代码，可用于计算使用Madgraph的任意QED和QCD过程的树级螺旋幅度。 Feynman振幅之间没有微妙的仪表取消仪表可以使数值代码准确地评估奇异行为，并帮助我们获得对干扰模式的物理见解。
We introduce photon and gluon propagators in which the scalar polarization component is subtracted systematically by making use of the BRST invariance of the off-shell vector boson created from physical on-shell states. The propagator has the light-cone gauge form, where the spacial component of the gauge vector points along the negative of the off-shell vector boson momentum. We call the gauge as parton-shower gauge, since in collinear configurations the absolute value squared of each Feynman amplitude reproduces all the singular behaviors of the corresponding parton shower in this gauge. We introduce new HELAS codes that can be used to calculate the tree-level helicity amplitudes of arbitrary QED and QCD processes by using MadGraph. The absence of subtle gauge cancellation among Feynman amplitudes allows numerical codes to evaluate singular behaviors accurately, and helps us gaining physical insights on interference patterns.
