Determination of the η-transition form factor in the γp→pη→pγe+e− reaction
Physics letters : B. Bd. 701. H. 5. Amsterdam: North-Holland Publ. 2011 S. 562 - 567
Erscheinungsjahr: 2011
ISBN/ISSN: 0370-2693
Publikationstyp: Zeitschriftenaufsatz
Sprache: Englisch
Doi/URN: 10.1016/j.physletb.2011.06.069
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Inhaltszusammenfassung
The Dalitz decay eta -> gamma e(+)e(-) 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(+)e(-) channel, statistics have been improved by one order of magnitude. The e(+)e(-)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-facto...The Dalitz decay eta -> gamma e(+)e(-) 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(+)e(-) channel, statistics have been improved by one order of magnitude. The e(+)e(-)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(m(2)) = (1 - m(2)/Lambda(2))(-1), a value of Lambda(-2) = (1.92 +/- 0.35(stat) +/- 0.13(syst)) GeV-2 has been determined. This value is in good agreement with a recent measurement of the eta Dalitz decay in the mu(+)mu(-) channel and with recent form-factor calculations. An improved value of the branching ratio BR(eta -> gamma e(+)e(-)) = (6.6 +/- 0.4(stat) +/- 0.4(syst)) . 10(-3) has been determined. (C) 2011 Elsevier B.V. All rights reserved.» weiterlesen» einklappen
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Klassifikation
DFG Fachgebiet:
Teilchen, Kerne und Felder
DDC Sachgruppe:
Physik
