Measurement of the cross-sections

Abstract

Reactions e^{ + }e^{-} \rightarrow D^{ + }D^{-}, e^{ + }e^{-} \rightarrow D^{ + }D \ast ^{-} and e^{ + }e^{-} \rightarrow D \ast ^{ + }D \ast ^{-} provide a test for QCD fragmentation models. In this paper, we report the first measurement of these processes. The cross-sections for e^{ + }e^{-} \rightarrow D \ast ^{ + }D \ast ^{-}, e^{ + }e^{-} \rightarrow D^{ + }D \ast ^{-} and e^{ + }e^{-} \rightarrow D^{ + }D^{-} are measured to be: 0.65, 0.71 pb, z and less than 0.04 pb (at 90% CL), respectively. In addition, we measure the fraction of D_{T}^{ \ast \pm } \hspace{0.167em} D_{L}^{ \ast \mp } in the e^{ + }e^{-} \rightarrow D \ast ^{ + }D \ast ^{-} reaction to be {\rm (97 \pm 5)%.} The analy..