a Study of the Asymmetry in the Photoproduction of D MESON(*+) and D MESON(*-) at Photon Energies of 40 TO 160 GEV

Evidence for an asymmetry in the photoproduction of D^*^+ and D^* ^- at photon energies of 40-160 GeV was found in Fermilab experiment E516. The experiment studied high energy gamma p interactions using the Tagged Photon Spectrometer, consisting of a sophisticated recoil detector to study the target fragments, and a large acceptance forward spectrometer. The charged D ^* signal was detected in the decay channel D^*^+ to D^0pi^{+}, with subsequent decay of the D^0 via the decay modes D^0 to K^-pi^+, D^0 to K ^-pi^+pi^+pi^ -, D^0 to K^0pi^+pi^-, or D^0 to K^-pi^+pi^0. Using the unique capabilities of the recoil detector to accurately indicate diffractive processes, the first direct measurement of the asymmetry (in the form of the ratio of anti-charmed to charmed D^* mesons) for purely non-diffractive processes was found to be 1.38 +/- 0.28. The data also showed no indication of asymmetric production for purely diffractive events. The asymmetry in the non-diffractive component of signal was interpreted as evidence for associated production of Lambda_sp{c}{+}D^* ^-, which was consistent with an earlier E516 report for the direct observation of associatively produced Lambda_sp{c}{+ }. Finally, the results were seen as consistent with previously reported photoproduction experiments conducted at different photon energy ranges.