Publications
Publication Information
| Title | On-shell representations of two-body transition amplitudes: single external current |
| Authors | Raul Briceno, Andrew Jackura, Felipe Ortega Gama, Keegan Sherman |
| JLAB number | JLAB-THY-20-3298 |
| LANL number | arXiv:2012.13338 |
| Other number | DOE/OR/23177-5094 |
| Document Type(s) | (Journal Article) |
| Associated with EIC: | No |
| Supported by Jefferson Lab LDRD Funding: | No |
| Funding Source: | Nuclear Physics (NP) |
|
Journal Compiled for Physical Review D Volume 103 Page(s) 114512 Refereed | |
| Publication Abstract: | Our understanding of many QCD phenomena relies on determining energy-dependent form-factors of few-body systems, from the structure of hadrons to extensions beyond the standard model. We obtain constraints on these two-body form-factors by using all-orders perturbation theory to study the analytic form of amplitudes for two-particle asymptotic states coupled via a single external current. The results presented hold for any external current, $\mathcal{J}$, with any quantum numbers. We consider asymptotic states which carry no intrinsic spin, and we make no assumptions about the underlying dynamics of their interactions. We verify the previously known form for the analytic structure of $1+\mathcal{J}\to2$ reactions with any number of intermediate two-particle states. Furthermore, we present previously unknown expressions of $2+\mathcal{J}\to2$ amplitudes, which can in turn be computed via lattice QCD. We identify the exact form of all singularities of these amplitudes near the real-energy axis of the initial and final states, including the triangle singularity. In addition to explaining the relation between the derived amplitudes and the elastic form factors of resonances, we explore the consequences of the narrow-width limit of the amplitudes as well as the role of the Ward-Takahashi identity for conserved vector currents. |
| Experiment Numbers: | other |
| Group: | THEORY CENTER |
| Document: | |
| DOI: | https://doi.org/10.1103/PhysRevD.103.114512 |
| Accepted Manuscript: | PhysRevD.103.114512.pdf |
| Supporting Documents: | |
| Supporting Datasets: | |