Year: 2014
Type: article
Abstract: An infinite number of physically nontrivial symmetries are found for abelian gauge theories with massless charged particles. They are generated by large U(1) gauge transformations that asymptotically approach an arbitrary function $$ \varepsilon \left(z,\overline{z}\right) $$ on the conformal sphere at future null infinity ( ) but are independent of the retarded time. The value of ε at past null infinity ( ) is determined from that on by the condition that it take the same value at either end of any light ray crossing Minkowski space. The ε ≠ constant symmetries are spontaneously broken in the usual vacuum. The associated Goldstone modes are zero-momentum photons and comprise a U(1) boson living on the conformal sphere. The Ward identity associated with this asymptotic symmetry is shown to be the abelian soft photon theorem.
Source: Journal of High Energy Physics
Institution: Harvard University
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: diamond
Funder: U.S. Department of Energy
OpenAlex ID: W2084162291