Determination of the eta-transition form factor in the gamma p -< p eta -< p gamma e(+)e(-) reaction

Berghaeuser, H. and Metag, V. and Starostin, A. and Bartolome, P. Aguar and Akasoy, L. K. and Annand, J. R. M. and Arends, H. J. and Bantawa, K. and Beck, R. and Bekrenev, V. and Braghieri, A. and Branford, D. and Briscoe, W. J. and Brudvik, J. and Cherepnya, S. and Demissie, B. T. and Downie, E. J. and Drexler, P. and Dieterle, M. and Fil`kov, L. V. and Fix, A. and Glazier, D. I. and Heid, E. and Hornidge, D. and Jahn, O. and Jude, T. C. and Kashevarov, V. L. and Knezevic, A. and Kondratiev, R. and Korolija, M. and Kotulla, M. and Koulbardis, A. and Kruglov, S. and Krusche, B. and Lemmer, B. and Lisin, V. and Livingston, K. and MacGregor, I. J. D. and Maghrbi, Y. and Manley, D. M. and Martinez-Fabregate, M. and McGeorge, J. C. and McNicoll, E. F. and Mekterovic, D. and Micanovic, S. and Mushkarenkov, A. and Nefkens, B. M. K. and Nikolaev, A. and Novotny, R. and Ostrick, M. and Owens, R. O. and Pedroni, P. and Pheron, F. and Polonski, A. and Robinson, J. and Prakhov, S. N. and Rosner, G. and Rostomyan, T. and Schumann, S. and Sober, D. and Suarez, I. M. and Supek, I. and Tarbert, C. M. and Thiel, M. and Thomas, A. and Unverzagt, M. and Watts, D. P. and Werthmueller, D. and Zamboni, I. and Zehr, F.. (2011) Determination of the eta-transition form factor in the gamma p -< p eta -< p gamma e(+)e(-) reaction. Physics Letters B, 701 (5). pp. 562-567.

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Abstract

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.

Faculties and Departments:	05 Faculty of Science > Departement Physik > Former Organization Units Physics > Hadronenphysik (Krusche)
UniBasel Contributors:	Krusche, Bernd
Item Type:	Article, refereed
Article Subtype:	Research Article
Publisher:	Elsevier
ISSN:	0370-2693
e-ISSN:	1873-2445
Note:	Publication type according to Uni Basel Research Database: Journal article
Language:	English
Identification Number:	doi: 10.1016/j.physletb.2011.06.069 isi: 000293438100007
edoc DOI:	10.5451/unibas-ep47290
Last Modified:	30 Jan 2017 08:41
Deposited On:	30 Jan 2017 08:41

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