Preliminary measurement of prompt D{sup {+-}} and D*{sup {+-}} meson production and D*{sup {+-}} spin alignment in hadronic Z{sup 0} decays

The authors have measured the production rates as a function of scaled energy x of prompt charmed pseudoscalar D{sup {+-}} and vector D*{sup {+-}} mesons in hadronic Z{sup 0} decays. The prompt signal components were isolated from the background of D mesons from B hadron decays using impact parameters of reconstructed D{sup {+-}} {yields} K{sup {minus_plus}}{pi}{sup {+-}}{pi}{sup {+-}} and D*-daughter D{sup 0} {yields} K{sup {minus}}{pi}{sup +} and D{sup 0} {yields} K{sup {minus}}{pi}{sup +}{pi}{sup {minus}}{pi}{sup +} candidates. Using the combined meson production rates the authors have measured the fraction of hadronic Z{sup 0} decays into c{bar c}, R{sub c} = 0.182 {+-} 0.027 (stat.) {+-} 0.012 (syst.) (Preliminary). Comparison of the D*{sup {+-}} and D{sup {+-}} rates gives a direct probe of vector (V) vs. pseudoscalar (P) meson production for charmed quarks, and for x > 0.4 they have measured P{sub V} = V/(V + P) = 0.65 {+-} 0.09(stat.) {+-} 0.03(syst.) {+-} 0.03 (BR) (Preliminary). They have measured the degree of spin alignment of the D*{sup {+-}} mesons along their flight direction and find it to be consistent with zero. They compared the latter two results with QCD- and model-based predictions of charm-quark jet fragmentation