Four-loop cusp anomalous dimension from obstructions

Four-Loop Cusp Anomalous Dimension From Obstructions

Freddy Cachazo, ∗ Marcus Spradlin, † and Anastasia Volovich ‡ Perimeter Institute for Theoretical Physics, Waterloo, Ontario N2J 2W9, Canada Brown University, Providence, Rhode Island 02912, USA Abstract We introduce a method for extracting the cusp anomalous dimension at L loops from four-gluon amplitudes inN = 4 Yang-Mills without evaluating any integrals that depend on the kinematical invari...

The Four-Loop Planar Amplitude and Cusp Anomalous Dimension in Maximally Supersymmetric Yang-Mills Theory

We present an expression for the leading-color (planar) four-loop four-point amplitude of N = 4 supersymmetric Yang-Mills theory in 4 − 2ǫ dimensions, in terms of eight separate integrals. The expression is based on consistency of unitarity cuts and infrared divergences. We expand the integrals around ǫ = 0, and obtain analytic expressions for the poles from 1/ǫ8 through 1/ǫ4. We give numerical...

The three-loop cusp anomalous dimension in QCD

We present the full analytic result for the three-loop angle-dependent cusp anomalous dimension in QCD. With this result, infrared divergences of planar scattering processes with massive particles can be predicted to that order. Moreover, we define a closely related quantity in terms of an effective coupling defined by the light-like cusp anomalous dimension. We find evidence that this quantity...

Cusp anomalous dimension in maximally supersymmetric

This talk is mainly based on the work [1] performed in collaboration with B. Basso1 and G. Korchemsky1, where the method of strong coupling expansion of the cusp anomalous dimension was found. The cusp anomalous dimension [2], called also the cusp, is a physical observable, which appears in many branches of particle physics. It is related with the logarithmic growth of the anomalous dimensions ...

Three-loop Cusp Anomalous Dimension and a Conjecture for N Loops