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Updated: May 23, 2026

Setting Limits on Supersymmetry Using Simplified Models
Published on: November 15, 2013
Puzzle of anomalously large isospin violations in η(1405/1475)→3π
Jia-Jun Wu1, Xiao-Hai Liu, Qiang Zhao
1Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.
Abstract:
The BES-III Collaboration recently reported the observation of anomalously large isospin violations in J/ψ→γη(1405/1475)→γπ(0)f(0)(980)→γ+3π, where the f(0)(980) in the ππ invariant mass spectrum appears to be much narrower (~10 MeV) than the peak width (~50 MeV) measured in other processes. We show that a mechanism, named as triangle singularity (TS), can produce a narrow enhancement between the charged and neutral KK¯ thresholds, i.e., 2m(K(±))~2m(K(0)). It can also lead to different invariant mass spectra for η(1405/1475)→a(0)(980)π and KK ¯*+c.c., which can possibly explain the long-standing puzzle about the need for two close states η(1405) and η(1475) in ηππ and KK¯π, respectively. The TS could be a key to our understanding of the nature of η(1405/1475) and advance our knowledge about the mixing between a(0)(980) and f(0)(980).
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