Observation of a new ηπ0π0 resonance at 1900 MeV/c2 in two-photon scattering

K. Karch, D. Antreasyan, H. W. Bartels, D. Besset, Ch Bieler, J. K. Bienlein, A. Bizzeti, E. D. Bloom, I. Brock, K. Brockmüller, R. Cabenda, A. Cartacci, M. Cavalli-Sforza, R. Clare, A. Compagnucci, G. Conforto, S. Cooper, R. Cowan, D. Coyne, A. EnglerK. Fairfield, G. Folger, A. Fridman, J. Gaiser, D. Gelphman, G. Glaser, G. Godfrey, K. Graaf, F. H. Heimlich, F. H. Heinsius, R. Hofstadter, J. Irion, Z. Jakubowski, H. Janssen, S. Keh, T. Kiel, H. Kilian, I. Kirkbride, T. Kloiber, M. Kobel, W. Koch, A. C. König, K. Königsmann, R. W. Kraemer, S. Krüger, G. Landi, R. Lee, S. Leffler, R. Lekebusch, A. M. Litke, W. Lockman, S. Lowe, B. Lurz, D. Marlow, H. Marsiske, W. Maschmann, P. McBride, F. Messing, W. J. Metzger, H. Meyer, B. Monteleoni, B. Muryn, R. Nernst, B. Niczyporuk, G. Nowak, C. Peck, P. G. Pelfer, B. Pollock, F. C. Porter, D. Prindle, P. Ratoff, M. Reidenbach, B. Renger, C. Rippich, M. Scheer, P. Schmitt, J. Schotanus, J. Schütte, A. Schwarz, D. Sievers, T. Skwarnicki, V. Stock, K. Strauch, U. Strohbusch, J. Tompkins, H. J. Trost, B. van Uitert, R. T. Van de Walle, H. Vogel, A. Voigt, U. Volland, K. Wachs, K. Wacker, W. Walk, H. Wegener, D. A. Williams, P. Zschorsch

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10 Scopus citations


Using the Crystal Ball detector at the DORIS II e+e- storage ring, we measure the ηπ0π0 mass spectrum in the reaction e+e-→e+e-ηπ 0π0→e+e-6γ from the ηπ0π0 threshold to about 2500 MeV/c2. The spectrum is dominated by the η′, for which we determine Γγγ(η′)BR(η'→6γ)=0 .36±0.02±0.03 keV. In addition, we observe an enhancement in the cross section near 1900 MeV/c2 which we attribute to the two-photon production of a new resonance X(1900). The angular distributions and the invariant mass distribution of the ηπ0 subsystem are consistent with those expected for the hypothetical η2 meson with JPC=2-+. For this JP assignment the resonance parameters are M(X) = 1876 ±35±50 MeV/c2, Γtot(X)=228±90±34 MeV/c2 and Γγγ(X)BR(X→ηππ) = 0.9±0.2±0.3 keV.

Original languageEnglish (US)
Pages (from-to)353-358
Number of pages6
JournalPhysics Letters B
Issue number2
StatePublished - Oct 18 1990
Externally publishedYes

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


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