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Author(s)
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Amsler, C ; Armstrong, D.S. ; Baker, C.A. ; Barnett, B.M. ; Batty, C.J. ; Benayoun, Maurice ; Beuchert, K. ; Birien, P. ; Blum, P. ; Bossingham, R. ; Braune, K. ; Brose, J. ; Bugg, D.V. ; Case, T. ; Cooper, A.R. ; Cramer, O. ; Crowe, K.M. ; Degener, T. ; Dietz, H.P. ; Dzhaoshvili, N.G. ; von Dombrowski, S. ; Doser, M. (CERN) ; Dunnweber, Wolfgang ; Engelhardt, D. ; Englert, M. ; Faessler, M.A. ; Felix, C. ; Giarritta, P. ; Hackmann, R. ; Haddock, R.P. ; Heinsius, F.H. ; Herz, M. ; Hessey, N.P. ; Hidas, P. ; Holtzhaussen, C. ; Illinger, P. ; Jamnik, D. ; Kalinowsky, H. ; Kalteyer, B. ; Kaemmle, B. ; Kiel, T. ; Kisiel, J. ; Klempt, E. ; Koch, H. ; Kobel, M. ; Kolo, C. ; Kunze, M. ; Lakata, M. ; Landua, R. ; Luedemann, J. ; Matthaey, H. ; McCrady, R. ; Merlo, J.P. ; Meyer, C.A. ; Montanet, L. ; Noble, A. ; Ouared, R. ; Ould-Saada, F. ; Peters, K. ; Pinder, C.N. ; Pinter, G. ; Ravndal, S. ; Regenfus, Christian ; Schaefer, E. ; Schmidt, P. ; Schuetrumpf, M. ; Seibert, R. ; Spanier, S. ; Stoeck, H. ; Strassburger, C. ; Strohbusch, U. ; Suffert, M. ; Thoma, U. ; Tischhaeuser, M. ; Urner, D. ; Voelcker, C. ; Walter, F. ; Walther, D. ; Wiedner, U. ; Winter, N. ; Zoll, J. ; Zou, B.S. ; Zupancic, C. |
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Abstract
| Upper limits for the production of new light gauge bosons in π0, η and η′ decays have been obtained with the Crystal Barrel detector. The kinematically well-constrained reactions p̅p → π0π0 P have been studied, where P ? π 0, η, η′ decays through the emission of a single photon recoiling against a missing state X. X can be a long-lived weakly interacting particle or it decays into ??̅. The resulting branching ratio upper limits (90 % C.L.) are: 6 × 10−5 for masses M X of the missing particle X lying between 65 MeV/c2 and 125 MeV/c2 (π0 decay), 6 × 10−5 for M X between 200 MeV/c2 and 525 MeV/c2 (gh decay), and 4 × 10−5 for M X between 50 MeV/c2 and 925 MeV/c2 (η′ decay). The π0-decay limit represents an improvement by a factor of 4 to 8 (depending on M X) when compared to the existing limit, whereas the η and η′ decay limits have been measured for the first time, thereby extending the M X range from 125 MeV/c2 up to 925 MeV/c2. |