A coordinate description of partonic processes

Understand

We review a perturbative description of amplitudes in coordinate space, aiming at an intuitive perspective on the roles of "long" and "short" distances.

• We begin with coordinate-space leading regions for fixed-angle scattering amplitudes, and develop approximations and factorizations in analogy to similar procedures in momentum space.
• There are also applications to products of Wilson lines, including the familiar cusp amplitude.
• We briefly discuss cross sections from the coordinate viewpoint, and the mechanism by which infrared singularities cancel in inclusive cross sections.