Triangulation-free Trivialization of 2-loop MHV Amplituhedron

Triangulation of 2-loop MHV Amplituhedron from Sign Flips

In this paper, we consider the triangulation of 2-loop MHV amplituhedron from "sign flip" definition. Using the isomorphism between $m=2, k=2$ tree amplituhedron and 1-loop MHV physical amplituhedron, we found the direct triangulation of 2-loop MHV amplituhedron from sign flip. This triangulation is different from the BCFW triangulation because of the structure of the cells. And we also found a formula of the canonical form of $n$-point 2-loop MHV amplituhedron. This formula looks like a 2-loop version of the Kermit representation of 1-loop MHV amplitude. We checked that the sum of these cells…

Positive geometry, local triangulations, and the dual of the Amplituhedron

We initiate the systematic study of \emph{local positive spaces} which arise in the context of the Amplituhedron construction for scattering amplitudes in planar maximally supersymmetric Yang-Mills theory. We show that all local positive spaces relevant for one-loop MHV amplitudes are characterized by certain sign-flip conditions and are associated with surprisingly simple logarithmic forms. In the maximal sign-flip case they are finite one-loop octagons. Particular combinations of sign-flip spaces can be glued into new local positive geometries. These correspond to local pentagon integrands t…

Cluster patterns in Landau and Leading Singularities via the Amplituhedron

We advance the exploration of cluster-algebraic patterns in the building blocks of scattering amplitudes in $\mathcal{N}=4$ super Yang-Mills theory. In particular we conjecture that, given a maximal cut of a loop amplitude, Landau singularities and poles of each Yangian invariant appearing in any representation of the corresponding Leading Singularities can be found together in a cluster. We check these adjacencies for all one-loop amplitudes up to 9 points. Along the way, we also prove that all (rational) N$^2$MHV Yangian invariants are cluster adjacent, confirming original conjectures.

双圈 MHV 动量 Amplituhedron：纤维化之纤维化

The Two-loop MHV Momentum Amplituhedron from Fibrations of Fibrations

本文提出将双圈纤维几何视为单圈运动学数据和第一圈动量位置的纤维化，刻画单圈腔室并给出典范形式，从而得到双圈 MHV 积分的新公式。

All-loop cuts from the Amplituhedron

The definition of the amplituhedron in terms of sign flips involves both one-loop constraints and the "mutual positivity" constraint. To gain an understanding of the all-loop integrand of $\mathcal{N}=4$ sYM requires understanding the crucial role played by mutual positivity. This paper is an attempt towards developing a procedure to introduce the complexities of mutual positivity in a systematic and controlled manner. As the first step in this procedure, we trivialize these constraints and understand the geometry underlying the remaining constraints to all loops and multiplicities. We present…

动量扭量图的幅面体

The Amplituhedron from Momentum Twistor Diagrams

本文提出了一种新的全环散射振幅/威尔逊圈的平面N=4 SYM的图解公式，称为“动量扭量图”。这些是通过粘合定义在动量扭量空间中的三价黑白顶点而获得的壳上图，在简化图的情况下，已知这些顶点与原始扭量空间中的图有关。新的图表是明显的杨安不变，他们自然代表因式分解和前向极限的贡献，在所有循环BCFW递归关系的动量扭量空间，在一种完全不同的方式，从那些在动量空间。我们将展示如何构建和评估动量扭量图，以及如何使用它们来获得树级振幅和循环级被积;特别是对于后者，我们确定了一个孤立的泡沫结构，每个循环变量，所产生的向前限制，或纠缠去除粒子。从一个给定的图表，可以直接读出的C，D矩阵通过一个广义的“边界测量”，这反过来又确定了一个细胞的振幅相关的振幅面体，和我们的图形表示的振幅可以提供三角形的振幅面体一般非常复杂的几何形状。为了证明该形式的计算能力，我们给出了一般双环被积函数的显式结果以及双环MHV振幅的完整振幅面的单元。