Asymptotic charges in massless QED revisited: a view from spatial infinity

• Main Authors: Miguel Campiglia, Alok Laddha
• Format: Article
• Language: English
• Published: SpringerOpen 2019-05-01
• Series: Journal of High Energy Physics
• Subjects: Gauge Symmetry; Global Symmetries; Scattering Amplitudes
• Online Access: http://link.springer.com/article/10.1007/JHEP05(2019)207

Abstract Hamada and Shiu have recently shown that tree level amplitudes in QED satisfy an infinite hierarchy of soft photon theorems, the first two of which are Weinberg and Low’s theorems respectively. In this paper we propose that in tree level massless QED, this entire hierarchy is equivalent to a hierarchy of (asymptotic) conservation laws. We prove the equivalence explicitly for the case of sub-subleading soft photon theorem and give substantial evidence that the equivalence continues to hold for the entire hierarchy. Our work also brings out the (complimentary) relationship between the asymptotic charges associated to soft theorems and the well known Newman-Penrose charges.