Shedding light on the nature of ϕ(2170) state in the e⁺e^- → ϕπ⁺π^- reaction

2025/09/16 by Wei, Xiang, Shen, Qing-Hua, Liu, Xiao-Hai +1
#FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph)

paper · doi:10.48550/arxiv.2509.12552

Abstract

We investigate the production of ϕ(2170) state in the e⁺e^- → ϕπ⁺π^- reaction with the effective Lagrangian approach. In addition to the tree level contributions from the ϕ(1680) meson and a possible X(1750) state, we consider also the K₁-K-K intermediate state process from the perspective of triangular singularity. Based on the one-photon exchange approximation, a pair of K₁ K mesons was firstly produced, and then the K₁ meson subsequently decays into ϕ and K, and the KK pair produce the π⁺ π^- through the final state interactions, in which the scalar meson f₀(980) is dynamically generated. We show that the inclusion of the triangle loop diagrams leads to a good description of the new BESIII measurements, especially for the structure of ϕ(2170). This provides a novel interpretation of the ϕ(2170) state, offering new insights into its fundamental nature which is still unclear. Furthermore, it is found that these measurements on the e⁺e^- → ϕπ⁺π^- reaction can be used to determine some of the properties of two K₁ mesons with masses around 1610 MeV and 1895 MeV, which are crucial to reproduce the experimental data.

Related

• The properties of ϕ(2170) and its three-body nature
• Measurement of e⁺e^- → K⁺K^-π⁰ cross section and observation of a resonant structure
• Roles of a₀(980) and a₀(1710) in Cabibbo-suppressed process D⁺→ π⁰π⁺η
• a₀(980) production, triangle singularity, and non-ϕ background in the J/ψ→ ϕηπ⁰ reaction
• Decoding the role of ρ mesonic states for elucidating the e⁺e^-→ a₂(1320)π data and other reactions