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Measurement of \Gamma(\eta -> \pi^+\pi^-\gamma)/\Gamma(\eta -> \pi^+\pi^-\pi^0) with the KLOE Detector
- Publication Year :
- 2012
-
Abstract
- The ratio R_{\eta}=\Gamma(\eta -> \pi^+\pi^-\gamma)/\Gamma(\eta -> \pi^+\pi^-\pi^0) has been measured by analyzing 22 million \phi \to \eta \gamma decays collected by the KLOE experiment at DA\PhiNE, corresponding to an integrated luminosity of 558 pb^{-1}. The \eta \to \pi^+\pi^-\gamma proceeds both via the \rho resonant contribution, and possibly a non-resonant direct term, connected to the box anomaly. Our result, R_{\eta}= 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 \eta -> \pi^+\pi^-\gamma decay could be described in a model-independent approach in terms of a single free parameter, \alpha. The determined value of the parameter \alpha is \alpha = (1.32 \pm 0.08_{stat} +0.10/-0.09_{syst}\pm 0.02_{theo}) GeV^{-2}<br />Comment: Paper in press, accepted by PLB
- Subjects :
- High Energy Physics - Experiment
Subjects
Details
- Database :
- arXiv
- Publication Type :
- Report
- Accession number :
- edsarx.1209.4611
- Document Type :
- Working Paper
- Full Text :
- https://doi.org/10.1016/j.physletb.2012.11.032