ITMP Seminar "Null Wilson loop with Lagrangian insertion in N=4 super Yang-Mills theory"

Dear Colleagues,

We are pleased to announce that the next ITMP seminar will be held on Wednesday, May 18, 18:00 (Moscow time). It will be arranged via zoom.

Speaker: Dmitry Chicherin, Annecy LAPTH

Title: Null Wilson loop with Lagrangian insertion in N=4 super Yang-Mills theory

Abstract:  Null Wilson loops in N = 4 super Yang-Mills are dual to planar scattering amplitudes. The duality holds at the level of their finite four-dimensional loop integrands as well as for the integrated observables with properly regularized infrared and cusp divergences. We consider a closely related infrared-finite four-dimensional observable which interpolates between the integrand and the fully loop-integrated quantity. It is defined as the null polygonal Wilson loop with a Lagrangian insertion normalized by the Wilson loop without insertion. Unlike the ratio and remainder functions of N = 4 super Yang-Mills amplitudes, this observable is non-trivial already at four points and it is reminiscent of finite parts of QCD amplitudes. We discuss the general structure of this n-point observable at weak coupling. At n>4, the loop corrections have rich kinematics. Indeed, there are several leading singularities and the accompanying loop functions are multivariable transcendental functions. We discuss a Grassmannian representation for the leading singularities and reveal their conformal and dual conformal symmetries. We conjecture a duality relation between the observable and the highest transcendentality piece of the planar all-plus amplitude in pure Yang-Mills theory. We test the duality using the one-loop n-point and two-loop four-point perturbative data for the observable. Relying on the duality, we predict the highest weight piece of the three-loop five-particle all-plus amplitude.

If you want to join the seminar please register here before 16:00, May 18.

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