2016/04/30 by Humberto Gomez · 1 citation
Physics and Astronomy · #hep-th
paper · pdf · doi:10.1007/jhep06(2016)101
published as JHEP 1606 (2016) 101 · v3: ref added, minor typos fixed
arxiv created 2016/06/22 · arxiv updated 2016/06/23
The CHY representation of scattering amplitudes is based on integrals over the moduli space of a punctured sphere. We replace the punctured sphere by a double-cover version. The resulting scattering equations depend on a parameter Λ controlling the opening of a branch cut. The new representation of scattering amplitudes possesses an enhanced redundancy which can be used to fix, modulo branches, the location of four punctures while promoting Λ to a variable. Via residue theorems we show how CHY formulas break up into sums of products of smaller (off-shell) ones times a propagator. This leads to a powerful way of evaluating CHY integrals of generic rational functions, which we call the Λ algorithm.