https://researchconnect.stonybrook.edu/en/publications/soft-photon-theorem-in-qcd-with-massless-quarks/
Soft Photon Theorem in QCD with Massless Quarks - Stony Brook University
stony brook universitysoft photontheoremqcdmassless
https://dr.iiserpune.ac.in/items/abe4bf12-ac5c-4472-8bf7-908f8806793a
Ward identity for loop level soft photon theorem for massless QED coupled to gravity
Motivated by Campiglia and Laddha [1], we show that the Sahoo-Sen soft photon theorem [2] for loop amplitudes is equivalent to an asymptotic conservation law....
ward identityfor loopsoft photonleveltheorem