Precision Study of η^{'}→γπ^{+}π^{-} Decay Dynamics

Area of Science:

• Particle Physics
• Hadron Spectroscopy
• Quantum Chromodynamics (QCD)

Background:

• The eta-prime (η′) meson is a key player in understanding light meson spectroscopy and QCD.
• Previous studies of η′ → γπ⁺π⁻ decays lacked sufficient statistics to resolve detailed dynamics.
• The BESIII detector at BEPCII provides unprecedented data for high-precision measurements.

Purpose of the Study:

• To investigate the decay dynamics of η′ → γπ⁺π⁻ using a significantly larger dataset.
• To identify and characterize contributions from various intermediate states and resonances.
• To compare results from model-dependent and model-independent analyses.

Main Methods:

• Analysis of 9.7 × 10⁵ J/ψ → γη′, η′ → γπ⁺π⁻ events collected by the BESIII detector.
• Application of both model-dependent and model-independent approaches to study decay dynamics.
• Statistical analysis to determine the significance of observed contributions.

Main Results:

• The contributions of the ω meson and the ρ(770)-ω interference are observed for the first time in η′ → γπ⁺π⁻ decays.
• A contribution from the 'box anomaly' or the ρ(1450) resonance is found to be necessary in the model-dependent analysis.
• The process-specific part of the decay amplitude is determined in the model-independent approach.

Conclusions:

• This study provides the most precise measurement to date of the η′ → γπ⁺π⁻ decay dynamics.
• The observation of ω and ρ(770)-ω interference offers new insights into the decay mechanisms of the η′ meson.
• The results necessitate further theoretical investigation into the role of the box anomaly or ρ(1450) resonance.