Exclusive Measurement of the eta --&gt; pi+ pi- gamma Decay
Creators: name: Adlarson, P.
name: Adolph, C.
name: Augustyniak, W.
name: Bardan, W.
name: Bashkanov, M.
name: Bednarski, T.
name: Bergmann, F. S.
name: Berłowski, M.
name: Bhatt, H.
name: Brinkmann, K. -T.
name: Büscher, M.
name: Calén, H.
name: Clement, H.
name: Coderre, D.
name: Czerwiński, E.
name: Doroshkevich, E.
name: Engels, R.
name: Erven, W.
name: Eyrich, W.
name: Fedorets, P.
name: Föhl, K.
name: Fransson, K.
name: Goldenbaum, F.
name: Goslawski, P.
name: Grigoryev, K.
name: Gullström, C. -O.
name: Hanhart, C.
name: Heijkenskjöld, L.
name: Heimlich, J.
name: Hejny, V.
name: Hinterberger, F.
name: Hodana, M.
name: Höistad, B.
name: Jacewicz, M.
name: Jany, A.
name: Jany, B. R.
name: Jarczyk, L.
name: Johansson, T.
name: Kamys, B.
name: Kemmerling, G.
name: Khakimova, O.
name: Khoukaz, A.
name: Kistryn, S.
name: Klaja, J.
name: Kleines, H.
name: Kłos, B.
name: Kren, F.
name: Krzemień, W.
name: Kulessa, P.
name: Kupść, A.
name: Lalwani, K.
name: Leupold, S.
name: Lorentz, B.
name: Magiera, A.
name: Maier, R.
name: Mariański, B.
name: Marciniewski, P.
name: Meißner, U. -G.
name: Mikirtychiants, M.
name: Morsch, H. -P.
name: Moskal, P.
name: Nandi, B. K.
name: Niedźwiecki, S.
name: Ohm, H.
name: Passfeld, A.
name: Pauly, C.
name: del Rio, E. Perez
name: Petri, T.
name: Petukhov, Y.
name: Piskunov, N.
name: Pluciński, P.
name: Podkopał, P.
name: Povtoreyko, A.
name: Prasuhn, D.
name: Pricking, A.
name: Pysz, K.
name: Pyszniak, A.
name: Rausmann, T.
name: Redmer, C. F.
name: Ritman, J.
name: Roy, A.
name: Rudy, Z.
name: Sawant, S.
name: Schadmand, S.
name: Schmidt, A.
name: Sefzick, T.
name: Serdyuk, V.
name: Shah, N.
name: Siemaszko, M.
name: Siudak, R.
name: Skorodko, T.
name: Skurzok, M.
name: Smyrski, J.
name: Sopov, V.
name: Stassen, R.
name: Stepaniak, J.
name: Sterzenbach, G.
name: Stockhorst, H.
name: Stollenwerk, F.
name: Szczurek, A.
name: Täschner, A.
name: Terschlüsen, C.
name: Tolba, T.
name: Trzciński, A.
name: Varma, R.
name: Vlasov, P.
name: Wagner, G. J.
name: Węglorz, W.
name: Winnemöller, A.
name: Wirzba, A.
name: Wolke, M.
name: Wrońska, A.
name: Wüstner, P.
name: Wurm, P.
name: Yuan, X.
name: Yurev, L.
name: Zabierowski, J.
name: Zheng, C.
name: Zieliński, M. J.
name: Zipper, W.
name: Złomańczuk, J.
name: Żuprański, P.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Nuclear Experiment (nucl-ex)
subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: An exclusive measurement of the decay eta --&gt; pi+ pi- gamma has been performed at the WASA facility at COSY. The eta mesons were produced in the fusion reaction pd --&gt; 3He X at a proton beam momentum of 1.7 GeV/c. Efficiency corrected differential distributions have been extracted based on 13340\pm140 events after background subtraction. The measured pion angular distribution is consistent with a relative p-wave of the two-pion system, whereas the measured photon energy spectrum was found at variance with the simplest gauge invariant matrix element of eta --&gt; pi+ pi- gamma. A parameterization of the data can be achieved by the additional inclusion of the empirical pion vector form factor multiplied by a first-order polynomial in the squared invariant mass of the pi+ pi- system.
description: 7 pages, 10 figures, submitted to Phys.Lett.B