Konishi form factors and cross sections in N=4 SYM

Abstract: Form factors are quantities involving both off-shell operators and
on-shell states. It may serve as a bridge to bring the amplitude techniques to the
off-shell world of correlation functions. It also provides promising new ideas to
compute higher-loop dilation operators, as well as to understand spin chain and
integrability. In this blackboard talk, we focus on the form factor of the prime
non-protected operator, the Konishi operator. We explain the on-shell unitarity
method of computing loop form factors. A subtlety related to the dimensional
regularization and four-dimensional unitarity will be discussed.  Since the Konishi
operator is not protected by supersymmetry, a few interesting QCD-like features
appear. Finally, we present several ways to subtract the IR divergences and obtain
the anomalous dimension, including using the cross section picture