Coupled-channel analysis of the near-threshold \(e^+e^-\to N\bar{N}\) cross sections

The possible existence of nucleon-antinucleon bound states has been studied for decades. We investigate the \(e^+e^-\to p\bar{p}\) and \(e^+e^-\to n\bar{n}\) cross sections in the nonrelativistic effective field theory framework. The proton-antiproton and neutron-antineutron coupled-channel final st...

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Bibliographic Details
Published in:arXiv.org 2024-10
Main Authors: Zhao-Sai, Jia, Zhang, Zhen-Hua, Feng-Kun, Guo, Li, Gang
Format: Article
Language:English
Subjects:
Amplitudes
Antinucleons
Antiparticles
Antiprotons
Cross-sections
Field theory
Protons
Online Access:Get full text
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Summary:The possible existence of nucleon-antinucleon bound states has been studied for decades. We investigate the \(e^+e^-\to p\bar{p}\) and \(e^+e^-\to n\bar{n}\) cross sections in the nonrelativistic effective field theory framework. The proton-antiproton and neutron-antineutron coupled-channel final state interactions are considered and found responsible for near-threshold enhancements. Both the proton-neutron mass difference and the Coulomb interaction between \(p\) and \(\bar{p}\) are considered, and the \(N\bar{N}\) strong interactions are taken into account through a short-distance optical potential. By fitting the low energy constants in the amplitudes to the data for the near-threshold \(e^+e^-\to N\bar{N}\) cross sections from the BESIII and SND Collaborations, a \(N\bar{N}\) quasi-bound state is found just above the \(p\bar{p}\) threshold, and another \(N\bar{N}\) pole is found on the unphysical Riemann sheet, farther away from the threshold. The constructed coupled-channel amplitude with Coulomb effects also offers a framework that can be used directly in experimental analyses on fine structures near the \(N\bar{N}\) thresholds.
ISSN:2331-8422