Abstract
An exclusive measurement of the decay η→π +π -γ has been performed at the WASA facility at COSY. The η mesons were produced in the fusion reaction pd→He3 X at a proton beam momentum of 1.7 GeV/c. Efficiency corrected differential distributions have been extracted based on 13960±140 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 η→π +π -γ. 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 π +π - system.
Original language | English |
---|---|
Pages (from-to) | 243-249 |
Number of pages | 7 |
Journal | Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics |
Volume | 707 |
Issue number | 2 |
DOIs | |
Publication status | Published - 20 Jan 2012 |
Keywords
- η meson
- Box anomaly
- Exclusive measurement
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In: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, Vol. 707, No. 2, 20.01.2012, p. 243-249.
Research output: Contribution to journal › Article › peer-review
TY - JOUR
T1 - Exclusive measurement of the η→π +π -γ decay
AU - Adlarson, P.
AU - Adolph, C.
AU - Augustyniak, W.
AU - Bardan, W.
AU - Bashkanov, M.
AU - Bednarski, T.
AU - Bergmann, F. S.
AU - Berłowski, M.
AU - Bhatt, H.
AU - Brinkmann, K. T.
AU - Büscher, M.
AU - Calén, H.
AU - Clement, H.
AU - Coderre, D.
AU - Czerwiński, E.
AU - Doroshkevich, E.
AU - Engels, R.
AU - Erven, W.
AU - Eyrich, W.
AU - Fedorets, P.
AU - Föhl, K.
AU - Fransson, K.
AU - Goldenbaum, F.
AU - Goslawski, P.
AU - Grigoryev, K.
AU - Gullström, C. O.
AU - Hanhart, C.
AU - Heijkenskjöld, L.
AU - Heimlich, J.
AU - Hejny, V.
AU - Hinterberger, F.
AU - Hodana, M.
AU - Höistad, B.
AU - Jacewicz, M.
AU - Jany, A.
AU - Jany, B. R.
AU - Jarczyk, L.
AU - Johansson, T.
AU - Kamys, B.
AU - Kemmerling, G.
AU - Khakimova, O.
AU - Khoukaz, A.
AU - Kistryn, S.
AU - Klaja, J.
AU - Kleines, H.
AU - Kłos, B.
AU - Kren, F.
AU - Krzemień, W.
AU - Kulessa, P.
AU - Kupść, A.
AU - Lalwani, K.
AU - Leupold, S.
AU - Lorentz, B.
AU - Magiera, A.
AU - Maier, R.
AU - Mariański, B.
AU - Marciniewski, P.
AU - Meißner, U. G.
AU - Mikirtychiants, M.
AU - Morsch, H. P.
AU - Moskal, P.
AU - Nandi, B. K.
AU - Niedźwiecki, S.
AU - Ohm, H.
AU - Passfeld, A.
AU - Pauly, C.
AU - Perez del Rio, E.
AU - Petri, T.
AU - Petukhov, Y.
AU - Piskunov, N.
AU - Pluciński, P.
AU - Podkopał, P.
AU - Povtoreyko, A.
AU - Prasuhn, D.
AU - Pricking, A.
AU - Pysz, K.
AU - Pyszniak, A.
AU - Rausmann, T.
AU - Redmer, C. F.
AU - Ritman, J.
AU - Rudy, Z.
AU - Sawant, S.
AU - Schadmand, S.
AU - Schmidt, A.
AU - Sefzick, T.
AU - Serdyuk, V.
AU - Siemaszko, M.
AU - Siudak, R.
AU - Skorodko, T.
AU - Skurzok, M.
AU - Smyrski, J.
AU - Sopov, V.
AU - Stassen, R.
AU - Stepaniak, J.
AU - Sterzenbach, G.
AU - Stockhorst, H.
AU - Stollenwerk, F.
AU - Ströher, H.
AU - Szczurek, A.
AU - Täschner, A.
AU - Terschlüsen, C.
AU - Tolba, T.
AU - Trzciński, A.
AU - Varma, R.
AU - Vlasov, P.
AU - Wagner, G. J.
AU - Weglorz, W.
AU - Winnemöller, A.
AU - Wirzba, A.
AU - Wolke, M.
AU - Wrońska, A.
AU - Wüstner, P.
AU - Wurm, P.
AU - Yuan, X.
AU - Yurev, L.
AU - Zabierowski, J.
AU - Zieliński, M. J.
AU - Zipper, W.
AU - Złomańczuk, J.
AU - Zuprański, P.
PY - 2012/1/20
Y1 - 2012/1/20
N2 - An exclusive measurement of the decay η→π +π -γ has been performed at the WASA facility at COSY. The η mesons were produced in the fusion reaction pd→He3 X at a proton beam momentum of 1.7 GeV/c. Efficiency corrected differential distributions have been extracted based on 13960±140 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 η→π +π -γ. 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 π +π - system.
AB - An exclusive measurement of the decay η→π +π -γ has been performed at the WASA facility at COSY. The η mesons were produced in the fusion reaction pd→He3 X at a proton beam momentum of 1.7 GeV/c. Efficiency corrected differential distributions have been extracted based on 13960±140 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 η→π +π -γ. 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 π +π - system.
KW - η meson
KW - Box anomaly
KW - Exclusive measurement
UR - http://www.scopus.com/inward/record.url?scp=84855333594&partnerID=8YFLogxK
U2 - 10.1016/j.physletb.2011.12.027
DO - 10.1016/j.physletb.2011.12.027
M3 - Article
AN - SCOPUS:84855333594
SN - 0370-2693
VL - 707
SP - 243
EP - 249
JO - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
JF - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
IS - 2
ER -