Charmed Meson Reconstruction In The D D 0 K Pi Pi Decay Channel In P P Collisions At S PDF Download

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.