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arXiv · 1304.0671

Search for a dark photon in the $π^0 \to e^+e^-γ$ decay

COSY Collaboration·P. Adlarson·W. Augustyniak·W. Bardan·M. Bashkanov·F. S. Bergmann·M. Berłowski·H. Bhatt·A. Bondar·M. Büscher·H. Calén·I. Ciepał·H. Clement·D. Coderre·E. Czerwiński·K. Demmich·E. Doroshkevich·R. Engels·W. Erven·W. Eyrich·P. Fedorets·K. Föhl·K. Fransson·F. Goldenbaum·P. Goslawski·A. Goswami·K. Grigoryev·C. -O. Gullström·F. Hauenstein·L. Heijkenskjöld·V. Hejny·F. Hinterberger·M. Hodana·B. Höistad·A. Jany·B. R. Jany·L. Jarczyk·T. Johansson·B. Kamys·G. Kemmerling·F. A. Khan·A. Khoukaz·S. Kistryn·J. Klaja·H. Kleines·B. Kłos·M. Krapp·W. Krzemień·P. Kulessa·A. Kupść·A. Kuzmin·K. Lalwani·D. Lersch·L. Li·B. Lorentz·A. Magiera·R. Maier·P. Marciniewski·B. Mariański·U. -G. Meißner·M. Mikirtychiants·H. -P. Morsch·P. Moskal·B. K. Nandi·H. Ohm·I. Ozerianska·E. Perez del Rio·N. Piskunov·P. Pluciński·P. Podkopał·D. Prasuhn·A. Pricking·D. Pszczel·K. Pysz·A. Pyszniak·C. F. Redmer·J. Ritman·A. Roy·Z. Rudy·S. Sawant·S. Schadmand·A. Schmidt·T. Sefzick·V. Serdyuk·N. Shah·B. Shwartz·M. Siemaszko·R. Siudak·T. Skorodko·M. Skurzok·J. Smyrski·V. Sopov·R. Stassen·J. Stepaniak·E. Stephan·G. Sterzenbach·H. Stockhorst·H. Ströher·A. Szczurek·T. Tolba
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Abstract

The presently world largest data sample of pi0 --> gamma e+e- decays containing nearly 5E5 events was collected using the WASA detector at COSY. A search for a dark photon U produced in the pi0 --> gamma U --> gamma e+e- decay from the pp-->ppπ^0 reaction was carried out. An upper limit on the square of the U-gamma mixing strength parameter epsilon^2 of 5e-6 at 90% CL was obtained for the mass range 20 MeV <M_U< 100 MeV. This result together with other recent experimental limits significantly reduces the M_U vs. ε^2 parameter space preferred by the measured value of the muon anomalous magnetic moment.

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COSY Collaboration, P. Adlarson, W. Augustyniak, W. Bardan, M. Bashkanov, F. S. Bergmann, M. Berłowski, H. Bhatt, A. Bondar, M. Büscher, H. Calén, I. Ciepał, H. Clement, D. Coderre, E. Czerwiński, K. Demmich, E. Doroshkevich, R. Engels, W. Erven, W. Eyrich, P. Fedorets, K. Föhl, K. Fransson, F. Goldenbaum, P. Goslawski, A. Goswami, K. Grigoryev, C. -O. Gullström, F. Hauenstein, L. Heijkenskjöld, V. Hejny, F. Hinterberger, M. Hodana, B. Höistad, A. Jany, B. R. Jany, L. Jarczyk, T. Johansson, B. Kamys, G. Kemmerling, F. A. Khan, A. Khoukaz, S. Kistryn, J. Klaja, H. Kleines, B. Kłos, M. Krapp, W. Krzemień, P. Kulessa, A. Kupść, A. Kuzmin, K. Lalwani, D. Lersch, L. Li, B. Lorentz, A. Magiera, R. Maier, P. Marciniewski, B. Mariański, U. -G. Meißner, M. Mikirtychiants, H. -P. Morsch, P. Moskal, B. K. Nandi, H. Ohm, I. Ozerianska, E. Perez del Rio, N. Piskunov, P. Pluciński, P. Podkopał, D. Prasuhn, A. Pricking, D. Pszczel, K. Pysz, A. Pyszniak, C. F. Redmer, J. Ritman, A. Roy, Z. Rudy, S. Sawant, S. Schadmand, A. Schmidt, T. Sefzick, V. Serdyuk, N. Shah, B. Shwartz, M. Siemaszko, R. Siudak, T. Skorodko, M. Skurzok, J. Smyrski, V. Sopov, R. Stassen, J. Stepaniak, E. Stephan, G. Sterzenbach, H. Stockhorst, H. Ströher, A. Szczurek, T. Tolba. 2013-08-27. Search for a dark photon in the $π^0 \to e^+e^-γ$ decay. https://doi.org/10.1016/j.physletb.2013.08.055

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