English

A possible explanation of the threshold enhancement in the process $e^+e^-\rightarrow \Lambda\bar{\Lambda}$

High Energy Physics - Phenomenology 2020-01-08 v2

Abstract

Inspired by the recent measurement of the process e+eΛΛˉe^+e^-\rightarrow \Lambda\bar{\Lambda}, we calculate the mass spectrum of the ϕ\phi meson with the GI model. For the excited vector strangeonium states ϕ(3S, 4S, 5S, 6S)\phi(3S,~4S,~5S,~6S) and ϕ(2D, 3D, 4D, 5D)\phi(2D,~3D,~4D,~5D), we further investigate the electronic decay width with the Van Royen-Weisskopf formula, and the partial widths of the ΛΛˉ\Lambda\bar{\Lambda}, Ξ()Ξˉ+\Xi^{-(*)}\bar{\Xi}^+, and Σ+()Σˉ()\Sigma^{+(*)}\bar{\Sigma}^{-(*)} decay modes with the extended quark pair creation model. We find that the electronic decay width of the DD-wave vector strangeonium is about 383\sim8 times larger than that of the SS-wave vector strangeonium. Around 2232 MeV the partial decay width of the ΛΛˉ\Lambda\bar{\Lambda} mode can reach up to several MeV for ϕ(33S1)\phi(3^3S_1), while the partial ΛΛˉ\Lambda\bar{\Lambda} decay width of ϕ(23D1)\phi(2^3D_1) is O(103)\mathcal{O}(10^{-3}) keV. If the threshold enhancement reported by the BESIII Collaboration arises from the strangeonium meson, this state is very likely to be the ϕ(33S1)\phi(3^3S_1) state. We also note that the ΛΛˉ\Lambda\bar{\Lambda} and Σ+Σˉ\Sigma^{+}\bar{\Sigma}^{-} partial decay widths of the states ϕ(33D1)\phi(3^3D_1) and ϕ(43S1)\phi(4^3S_1) are about several MeV, respectively, which are enough to be observed in future experiments.

Keywords

Cite

@article{arxiv.1904.06616,
  title  = {A possible explanation of the threshold enhancement in the process $e^+e^-\rightarrow \Lambda\bar{\Lambda}$},
  author = {Li-Ye Xiao and Xin-Zhen Weng and Xian-Hui Zhong and Shi-Lin Zhu},
  journal= {arXiv preprint arXiv:1904.06616},
  year   = {2020}
}

Comments

9 pages, 5 figures, to be published in Chinese Physics C

R2 v1 2026-06-23T08:38:49.907Z