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We compute the symbol of the first two-loop amplitudes in planar ${\cal N}=4$ SYM with algebraic letters, the eight-point NMHV amplitude (or the dual octagon Wilson loops). We show how to apply $\bar{Q}$ equations for computing the…

High Energy Physics - Theory · Physics 2020-03-25 Chi Zhang , Zhenjie Li , Song He

The $\bar{Q}$ equations, rooted in the dual superconformal anomalies, are a powerful tool for computing amplitudes in planar $\mathcal{N}=4$ supersymmetric Yang-Mills theory. By using the $\bar{Q}$ equations, we compute the symbol of the…

High Energy Physics - Theory · Physics 2022-01-05 Zhenjie Li , Chi Zhang

It is widely expected that NMHV amplitudes in planar, maximally supersymmetric Yang-Mills theory require symbol letters that are not rationally expressible in terms of momentum-twistor (or cluster) variables starting at two loops for eight…

High Energy Physics - Theory · Physics 2022-08-24 Jacob L. Bourjaily , Andrew J. McLeod , Cristian Vergu , Matthias Volk , Matt von Hippel , Matthias Wilhelm

We study a scalar component of the 8-point next-to-next-to-maximally-helicity-violating (N${}^2$MHV) amplitude at two-loop level in ${\cal N}=4$ super-Yang-Mills theory; it has a leading singularity proportional to the inverse of the…

High Energy Physics - Theory · Physics 2023-01-18 Song He , Zhenjie Li , Chi Zhang

In this sequel to arXiv:1711.11507 we classify the boundaries of amplituhedra relevant for determining the branch points of general two-loop amplitudes in planar $\mathcal{N}=4$ super-Yang-Mills theory. We explain the connection to on-shell…

High Energy Physics - Theory · Physics 2018-05-17 Igor Prlina , Marcus Spradlin , James Stankowicz , Stefan Stanojevic

We bootstrap the two-loop four-point next-to-maximally helicity-violating (NMHV) ratio function for the chiral stress-tensor form factor in planar maximally supersymmetric Yang-Mills theory (sYM) at the symbol level. Starting from an ansatz…

High Energy Physics - Theory · Physics 2026-05-29 Song He , Jiahao Liu , Qinglin Yang

We study Feynman integrals and scattering amplitudes in ${\cal N}=4$ super-Yang-Mills by exploiting the duality with null polygonal Wilson loops. Certain Feynman integrals, including one-loop and two-loop chiral pentagons, are given by…

High Energy Physics - Theory · Physics 2021-06-16 Song He , Zhenjie Li , Qinglin Yang , Chi Zhang

Symbol alphabets of n-particle amplitudes in N=4 super-Yang-Mills theory are known to contain certain cluster variables of Gr(4,n) as well as certain algebraic functions of cluster variables. In this paper we suggest an algorithm for…

High Energy Physics - Theory · Physics 2020-12-02 Jorge Mago , Anders Schreiber , Marcus Spradlin , Anastasia Volovich

We study the symbol of the two-loop n-gluon MHV amplitude for all Mandelstam regions in multi-Regge kinematics in N=4 super Yang-Mills theory. While the number of distinct Mandelstam regions grows exponentially with n, the increase of…

High Energy Physics - Theory · Physics 2018-01-18 Till Bargheer , Georgios Papathanasiou , Volker Schomerus

We derive analytic results for the symbol of certain two-loop Feynman integrals relevant for seven- and eight-point two-loop scattering amplitudes in planar $\mathcal{N}=4$ super-Yang--Mills theory. We use a bootstrap inspired strategy,…

High Energy Physics - Theory · Physics 2018-11-14 Johannes Henn , Enrico Herrmann , Julio Parra-Martinez

Two-loop MHV amplitudes in planar ${\cal N} = 4$ supersymmetric Yang Mills theory are known to exhibit many intriguing forms of cluster-algebraic structure. We leverage this structure to upgrade the symbols of the eight- and nine-particle…

High Energy Physics - Theory · Physics 2021-07-14 John Golden , Andrew J. McLeod

We describe a general algorithm which builds on several pieces of data available in the literature to construct explicit analytic formulas for two-loop MHV amplitudes in N=4 super-Yang-Mills theory. The non-classical part of an amplitude is…

High Energy Physics - Theory · Physics 2015-06-19 John Golden , Marcus Spradlin

I present a conjecture that all two-loop MHV amplitudes in planar $\mathcal{N} = 4$ super-Yang-Mills theory possess an antipodal symmetry when evaluated on parity-even kinematics. The symmetry acts as a change of basis on the symbol…

High Energy Physics - Theory · Physics 2022-09-28 Yu-Ting Liu

We compute the six-particle maximally-helicity-violating (MHV) amplitude in planar ${\cal N}=4$ super-Yang-Mills theory at eight loops, using antipodal duality and the recently computed eight-loop three-point form factor for the chiral…

High Energy Physics - Theory · Physics 2023-08-17 Lance J. Dixon , Yu-Ting Liu

In this paper we consider multi-loop integrals appearing in MHV scattering amplitudes of planar N=4 SYM. Through particular differential operators which reduce the loop order by one, we present explicit equations for the two-loop…

High Energy Physics - Theory · Physics 2015-06-04 L. Ferro

We introduce a method to extract the symbol of the coefficient of $(2\pi i)^2$ of MHV remainder functions in planar N=4 Super Yang-Mills in multi-Regge kinematics region directly from the symbol in full kinematics. At two loops this symbol…

High Energy Physics - Theory · Physics 2019-02-20 Vittorio Del Duca , Claude Duhr , Falko Dulat , Brenda Penante

We present an explicit analytic calculation of the differential of the planar n-particle, two-loop MHV scattering amplitude in N=4 super Yang-Mills theory. The result is expressed only in terms of the polylogarithm functions Li_k(-x), for…

High Energy Physics - Theory · Physics 2015-06-16 John Golden , Marcus Spradlin

We revisit the symbol bootstrap program for the seven-particle MHV and NMHV amplitudes in planar $\mathcal{N}=4$ super-Yang-Mills (SYM) based on the alphabet associated with the $E_6$ cluster algebra. After imposing integrability, cluster…

High Energy Physics - Theory · Physics 2025-11-24 Song He , Xuhang Jiang , Xiang Li , Jiahao Liu

We present an all-loop dispersion integral, well-defined to arbitrary logarithmic accuracy, describing the multi-Regge limit of the 2->5 amplitude in planar N=4 super Yang-Mills theory. It follows from factorization, dual conformal symmetry…

We provide a simple analytic formula for the two-loop six-point ratio function of planar N = 4 super Yang-Mills theory. This result extends the analytic knowledge of multi-loop six-point amplitudes beyond those with maximal helicity…

High Energy Physics - Theory · Physics 2015-06-03 Lance J. Dixon , James M. Drummond , Johannes M. Henn
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