Jun 13 – 17, 2011
Europe/Berlin timezone
Proceedings are now available online at <a href="http://www.slac.stanford.edu/econf/C110613/">eConf</a>

Determination of the eta transition form-factor from the eta --> e+ e- gamma decay

Jun 14, 2011, 5:10 PM
Festsaal (Künstlerhaus)



talk Light Mesons Light Mesons


Prof. Volker Metag Metag (II. Physikalisches Institut)


Volker Metag University of Giessen, Germany for the A2 collaboration The Dalitz decay η → γe+e− has been investigated in photo-nuclear reactions with the Crystal Ball/TAPS detector system at the electron accelerator MAMI-C. The Dalitz decay events were identified in an exclusive analysis exploiting the full kinematic information. Statistics improved by an order of magnitude compared to the most recent measurement in the e+e− channel allowed to determine the slope bη of the electromagnetic transition form factor F (q2) = (1 − q2/Λ2)−1 to bη = Λ−2 = (1.89 ± 0.35(stat) ± 0.1(syst)) GeV−2. This value is in good agreement with a recent measurement of the η Dalitz decay in the μ+μ− channel and with recent form-factor calculations. An improved branching ratio BR(η → γe+e−) = (6.21 ± 0.50) · 10−3 has been determined. Funded by DFG(SFB/TR-16)

Primary author

Prof. Volker Metag Metag (II. Physikalisches Institut)

Presentation materials