Measurement of Γ(η-> π^+π^-γ)/Γ(η-> π^+π^-π^0) with the KLOE Detector

Abstract

The ratio R_η=Γ(η-> π^+π^-γ)/Γ(η-> π^+π^-π^0) has been measured by analyzing 22 million ϕ\to ηγdecays collected by the KLOE experiment at DA\PhiNE, corresponding to an integrated luminosity of 558 pb^{-1}. The η\to π^+π^-γproceeds both via the ρresonant contribution, and possibly a non-resonant direct term, connected to the box anomaly. Our result, R_η= 0.1856\pm 0.0005_{stat} \pm 0.0028_{syst}, points out a sizable contribution of the direct term to the total width. The di-pion invariant mass for the η-> π^+π^-γdecay could be described in a model-independent approach in terms of a single free parameter, α. The determined value of the parameter αis α= (1.32 \pm 0.08_{stat} +0.10/-0.09_{syst}\pm 0.02_{theo}) GeV^{-2}

arXiv commentPaper in press, accepted by PLB

References in corpus (9)

• Big-Bang nucleosynthesis (Particle Data Group mini-review)
• The Cosmological Parameters 2006
• Data handling, reconstruction, and simulation for the KLOE experiment
• Model-independent approach to eta -> pi+ pi- gamma and eta' -> pi+ pi- gamma
• Chiral Anomaly and Eta-Eta' Mixing
• Exclusive Measurement of the eta --> pi+ pi- gamma Decay
• Anomalous $\eta /{\eta }^{\prime }$ Decays: The Triangle and Box Anomalies
• Measurement of Prominent eta Decay Branching Fractions
• eta, eta-prime -> pi^+ pi^- gamma with coupled channels

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