Search for Charmed Mesons Produced in Hadronic Interactions

The hadronic production of charmed states was studied in a two-arm spectrometer using a 205-GeV/c negative-pion beam incident upon a beryllium target. One arm, filled with dense absorber, triggered the detectors upon the passage of a muon with a moderate transverse momentum and a total momentum of at least 4 GeV/c. The other arm was an open-geometry magnetic spectrometer which had both neutral- and charged-particle identification capabilities. The apparatus, the data, and an invariant-mass-plot search for evidence of charmed-meson production through several charged-particle decay modes are described. The K..pi.., K..pi pi.., and K..pi pi pi.. mass plots fail to reveal significant D-meson signals. Based upon the K..pi.. mass plots, the 95%-confidence upper limit on the DD-bar production cross section is found to be less than 51 ..mu..b per nucleon for the production models tested. A search for evidence of charged-D/sup */ production yields 30 +- 16 combinations above background in association with the expected trigger muon charge. Interpreted as a D/sup */ signal, this excess corresponds to a model-dependent inclusive DD-bar production cross section of 34 +- 18/sub -9//sup +14/ ..mu..b per nucleon. Model-dependent upper limits on the ratio of the F to D cross sections are also presented.