Seventy-one events containing charmed-particle decays have been observed in an experiment using the SLAC Hybrid Facility exposed to a backward-scattered photon beam. Several improvements were made to the apparatus since the previous experiment on charm photoproduction. Results for the charmed-meson lifetimes are consistent with the published results from the previous experiment and the two data samples have been combined yielding a total sample of 136 charm events. After imposing rigorous cuts, 50 neutral, 48 charged, and 2 charged/neutral ambiguous decays remain. From these, the charmed-meson lifetimes are measured to be &=(8.61.3-0.3+0. 7)×10-13 sec, &=(220.127.116.11)×10 -13 sec, and their ratio &=1.40.3- 0.1+0.2. The total charm cross section at a photon energy of 20 GeV has been measured to be (628-10+15) nb. There is evidence for both DDX and Dc+X production with Dc+X/charm=(71 116)%.
ASJC Scopus subject areas
- Nuclear and High Energy Physics