2025/04/23 by Ai-Chao Wang, Neng-Chang Wei, Wang, Ai-Chao +1
Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #High-Energy Particle Collisions Research #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions
paper · pdf · doi:10.48550/arxiv.2504.16444
openalex publication_date 2025/04/23 · openalex created_date 2025/10/18 · openalex updated_date 2026/07/28
The γp → π0 ηp reaction has been investigated by the CBELSA/TAPS Collaboration, revealing a narrow structure in the ηp invariant mass distributions at a mass of 1700 MeV. In this study, we explore the possibility that the narrow structure is caused by a decay cascade via an intermediate nucleon resonance decaying to ηp final states. The candidates for the intermediate nucleon resonances are N(1700)3/2- and N(1710)1/2+, with masses near the observed structure. We consider the t-channel ρ- and ω-exchange diagrams, the u-channel nucleon-pole exchange diagram, the contact term, and the s-channel pole diagrams of nucleon, Δ, and nucleon resonances when constructing the reaction amplitudes to reproduce the stripped individual contribution of the narrow structure. Our analysis indicates that the signature strength of the decay cascade γp → π0N(1700)3/2- → π0ηp is too weak to reach the experimental curve of the narrow structure due to the small decay branching ratio of N(1700)3/2- to ηp. Although the decay cascade γp → π0N(1710)1/2+ → π0ηp can qualitatively reproduce the experimental curve of the invariant mass distributions, its cross-section width is much larger than that of the corresponding experimental curve. Therefore, we conclude that the decay cascade via an intermediate nucleon resonance could not be the reason leading to the narrow structure in the ηp invariant mass distributions of the γp → π0 ηp reaction.