# Loop-corrected soft photon theorems and large gauge transformations

### APA

Choi, S. (2023). Loop-corrected soft photon theorems and large gauge transformations. Perimeter Institute. https://pirsa.org/23100115

### MLA

Choi, Sangmin. Loop-corrected soft photon theorems and large gauge transformations. Perimeter Institute, Oct. 24, 2023, https://pirsa.org/23100115

### BibTex

@misc{ pirsa_PIRSA:23100115, doi = {10.48660/23100115}, url = {https://pirsa.org/23100115}, author = {Choi, Sangmin}, keywords = {Quantum Fields and Strings}, language = {en}, title = {Loop-corrected soft photon theorems and large gauge transformations}, publisher = {Perimeter Institute}, year = {2023}, month = {oct}, note = {PIRSA:23100115 see, \url{https://pirsa.org}} }

Sangmin Choi University of Amsterdam

**Collection**

**Talk Type**Scientific Series

**Subject**

## Abstract

In the last few years, a remarkable link has been established between the soft theorems and asymptotic symmetries of quantum field theories: soft theorems are Ward identities of the asymptotic symmetry generators. In quantum electrodynamics, Weinberg's soft photon theorem is nothing but the Ward identity of a gauge transformation whose parameter is non-trivial at infinity. Likewise, Low's tree-level subleading soft photon theorem is the Ward identity of a gauge transformation whose parameter diverges linearly at infinity. More recently, it has been shown that Low's theorem receives loop corrections that are logarithmic in soft photon energy. Then, it is natural to ask whether such corrections are associated with some asymptotic symmetry of the S-matrix. There have been proposals for conserved charges whose Ward identities yield the loop-corrected soft theorems, but a clear symmetry interpretation remains elusive. We explore this question in the context of scalar QED, in hopes of shedding light on the connection between asymptotic symmetries and loop-corrected soft theorems.

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