# Subthreshold poles in electron-positron annihilation. DD final states

**Authors:** Peter Lichard  
**arXiv:** [2505.18540](https://arxiv.org/abs/2505.18540)  
**Date:** 2025-05-24  
**Summary page:** https://www.summarizepaper.com/en/arxiv-id/2505.18540v1/

## Key points

- The study focuses on the influence of the ${\psi(2\mathrm S)}$ subthreshold pole on electron-positron annihilation into ${\mathrm D\bar\mathrm D}$ final states.
- Statistical significance of the subthreshold pole exceeds 4$\sigma$ in all cases, as demonstrated by fitting to BESIII data and conducting two common fits.
- Previous work by various researchers such as V. ˇCern´y, P. Lichard, J.I. Kapusta, C. Gale, R.J. Eden et al., N. Isgur et al., G.J. Gounaris and J.J. Sakurai is referenced, showing a rich history of research in this area.
- Methodology for parameter estimation in fitting models to experimental data is discussed, emphasizing the importance of accurately determining statistical significance of resonances through careful analysis of free parameters and their impact on cross sections.
- Supplemental material related to the research is provided for further exploration, contributing to a comprehensive understanding of subthreshold poles and cross sections in electron-positron annihilation processes leading to ${\mathrm D\bar\mathrm D}$ final states.

## Summary

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This study explores the influence of the ${\psi(2\mathrm S)}$ subthreshold pole on the cross section of electron-positron annihilation into ${\mathrm D\bar\mathrm D}$ final states. By fitting to BESIII data and conducting two common fits, it is demonstrated that the statistical significance of the subthreshold pole exceeds 4$\sigma$ in all cases. This research builds upon previous work by V. ˇCern´y, P. Lichard, J.I. Kapusta, C. Gale, and others who have contributed to understanding subthreshold poles in various contexts. References are also made to studies by R.J. Eden et al., N. Isgur et al., G.J. Gounaris and J.J. Sakurai, among others, highlighting a rich history of research in this area. The methodology used for parameter estimation in fitting models to experimental data is delved into, emphasizing the importance of accurately determining the statistical significance of resonances through careful analysis of free parameters and their impact on cross sections. Additionally, supplemental material related to the research is provided for further exploration. Overall, this comprehensive investigation sheds light on the intricate interplay between subthreshold poles and cross sections in electron-positron annihilation processes leading to ${\mathrm D\bar\mathrm D}$ final states. The findings not only contribute to our understanding of these phenomena but also underscore the significance of rigorous statistical analysis in extracting meaningful insights from experimental data in particle physics research.