The cusp anomalous dimension at three loops and beyond
Dr. Johannes Henn (IAS Princeton)

The anomalous dimension of a cusped Wilson loop appears in a number of physical situations. For example, it describes the infrared divergences of processes involving heavy quarks. In this talk, we discuss the cusp anomalous dimension in N=4 super Yang-Mills. In a small angle limit, we obtain an exact result that interpolates between weak and strong coupling.
For generic angle, we introduce a new limit that maps the computation to a quantum mechanical problem. We also describe how the cusp anomalous dimension is related to the Regge limit of massive amplitudes on the Coulomb branch of N=4 super Yang-Mills. This relation is used to obtain the full three-loop answer. We discuss the structure of this result and point out lessons that can be drawn for QCD.