Abstract
We calculate the collinear anomalous dimensions in massless four-loop QCD and N=4 supersymmetric Yang-Mills theory from the infrared poles of vertex form factors. We give very precise numerical approximations and a conjecture for the complete analytic results in both models we consider.
Highlights
Over the last several years, significant attention has been given to the calculation of cusp and collinear anomalous dimensions in massless perturbation theory
Partial results are available at four-loop order both in Quantum Chromodynamics (QCD) [3,6,7,11,8,29,30,17] and N = 4 supersymmetric Yang-Mills theory (N = 4 SYM) [31,32,33]
In QCD, the basic quark and gluon form factors are the normalized amplitudes for, respectively, a virtual photon decaying into a pair of massless quarks, γ ∗(q) → q(p1)q(p2), and a Higgs boson decaying into two gluons in the limit of infinite top quark mass, h(q) → g(p1)g(p2), whereas in N = 4 SYM, the Sudakov form factor is the normalized amplitude
Summary
Over the last several years, significant attention has been given to the calculation of cusp and collinear anomalous dimensions in massless perturbation theory. The light-like cusp anomalous dimensions [1] enter the leading infrared poles of massless scattering amplitudes and have recently been calculated to four-loop order both in Quantum Chromodynamics (QCD) and N = 4 supersymmetric Yang-Mills theory (N = 4 SYM) [2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17].
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