Generalizations of the Double-Copy: the KLT Bootstrap

Understand

We formulate a new program to generalize the double-copy of tree amplitudes.

• The approach exploits the link between the identity element of the KLT algebra and the KLT kernel, and we demonstrate how this leads to a set of KLT bootstrap equations that the double-copy kernel has to satisfy (in addition to locality constraints).
• We solve the KLT bootstrap equations perturbatively to find the most general higher-derivative corrections to the 4- and 5-point field theory KLT kernel.
• The new kernel generalizes the string KLT kernel and its associated monodromy relations.