  We propose that certain twists of the su(2|2) S-matrix elements describe the
beta-deformation of N=4 supersymmetric Yang-Mills theory. We compute the
perturbative four-loop anomalous dimension of the Konishi operator of the
deformed gauge theory from the Luscher formula based on these twisted S-matrix
elements. The result agrees exactly with the perturbative gauge theory
computations.
