Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10721930 | Physics Letters B | 2011 | 6 Pages |
Abstract
The Dalitz decay ηâγe+eâ has been measured using the combined Crystal Ball and TAPS photon detector setup at the electron accelerator MAMI-C. Compared to the most recent transition form-factor measurement in the e+eâ channel, statistics have been improved by one order of magnitude. The e+eâ invariant mass distribution shows a deviation from the QED prediction for a point-like particle, which can be described by a form-factor. Using the usual monopole transition form-factor parameterization, F(m2)=(1âm2/Î2)â1, a value of Îâ2=(1.92±0.35(stat)±0.13(syst)) GeVâ2 has been determined. This value is in good agreement with a recent measurement of the η Dalitz decay in the μ+μâ channel and with recent form-factor calculations. An improved value of the branching ratio BR(ηâγe+eâ)=(6.6±0.4(stat)±0.4(syst))â
10â3 has been determined.
Keywords
Related Topics
Physical Sciences and Engineering
Physics and Astronomy
Nuclear and High Energy Physics
Authors
H. Berghäuser, V. Metag, A. Starostin, P. Aguar Bartolomé, L.K. Akasoy, J.R.M. Annand, H.J. Arends, K. Bantawa, R. Beck, V. Bekrenev, A. Braghieri, D. Branford, W.J. Briscoe, J. Brudvik, S. Cherepnya, B.T. Demissie, E.J. Downie, P. Drexler, F. Zehr,