Observation of the Decay +yp " Po *

Submitted to Physical Review Letters * Work supported in part by the Department of Energy, contracts DE-AC03-76SF00515 and W-7405-ENG-48, by the UniversitH’t Bonn, Federal Republic of Germany, the Centre d’Etudes Nucleaires de Saclay, France, and the Miller Institute for Basic Research in Science, Berkeley, California. (a). Present address: Vanderbilt University, Nashville, TN 37235. (b). Present address: Harvard University, Cambridge, MA 02138. (cl. Present address: LPNHE, Ecole Polytechnique, F-91128 Palaiseau, France (d). Present address: Carnegie-Mellon University, Pittsburgh, PA 15213 tel. Present address: DESY, Hamburg, Federal Republic of Germany. tf). Present address: CERN, CH-1211 Geneva 23, Switzerland (g). Present address: California Institute of Technology, Pasadena, CA 91125. (h). Present address: CEN Saclay, F-91190 Gif-sur-Yvette, France (il. Present address: Phys. Inst. RWTH Aachen, F. R. Germany Cj>. Present address: Argonne National Laboratory, Argonne, IL 60439. The remarkably narrou uidth of the $(3095) implies a strong OZI suppression of the three gluon decay of the jSq cc bound state. Prompt photons produced in $ decays are therefore expected to be predominantly emitted from an initial charmed quark rather than from a final state quark since this requires only two gluons to mediate the decay. The possibility that gluonic bound states might be observed in these decays has led to considerable experimental effort’ at the SPEAR and DORIS electron-positron colliding beam facilities. We report in this Letter a study of the decay 9(3095) -D YlT+o-lr+11’. (1) Likelihood fits to the four-pion system provide evidence for the decay $(3095) + rpopo # (2) . with pop0 invariant masses concentrated betueen 1.4 GeV/cZ and 2.0 GeV/c*. Enhancements in the pop0 channel in this mass range have previously been reported in hadronic reactions2 and observed in final states produced by photon-photon collisions3. The data for this experiment were taken uith the Mark XI detector’ at SPEAR and correspond to “650,000 produced 9 mesons. Events were considered candidates for the prompt photon decay (11 if they contained four charged particles uith zero net charge and at least one photon detected in the electromagnetic calorimeters with energy greater than 300 MeV. Candidate events were removed from further consideration if they contained a pair of tracks that formed a secondary vertex consistent with a KS0 decay, or if any of the prongs were determined by the