Charmed Meson and Onium Production at the Tevatron

We report recent results of D meson, J== and production at the Fermilab Tevatron. We observe about 8000 D mesons reconstructed in the decay chain of D ! D 0 ; D 0 ! K+X. We measure the integrated D + production cross section to be 34765(stat:)58(sys:) nb for the rapidity range j(D +)j < 1:0 and the transverse momentum range pT (D +) > 10 GeV/c. The measurement is slightly higher than the theoretical prediction, especially at lower pT range. We also measure the polarization of J== at production and nd that the measured transverse polarization is not well explained by the color-octet model proposed to explain the anomalously high J== production cross section. We also present a new result on production and polarization. Production of the is consistent with being unpolarized. The charmed meson production cross section gives complementary information on high energy heavy quark production mechanisms to the previously measured b-quark cross sections. In this paper, we present the rst measurement of charmed meson production in pp collisions at p s = 1:8 TeV. A D meson is reconstructed through the decay chain D ! D 0 ; D 0 ! K+X, where we triggered the event on a muon of p T greater than 7:5 GeV=c. The D meson signature is the small mass diierence between the D meson and the daughter D 0 meson. In this analysis, we identify the D events from the mass diierence between (K; ;) and (K;). We denote M as this mass diierence hereafter. In Figure 1, we show the M distributions for events with the right-sign combination (RS) and events with the wrong-sign combination (WS). The RS represents a combination of K , and the WS is K. In Figure 1, we observe a clear peak for D events in RS. The M distribution for WS is used to estimate the background distribution. We