Precision measurements of charm hadron properties at Babar

Abstract

We present preliminary results on the natural line width, $\Gamma(D^{*+})$, in the transition $D^{*}(2010)^{+} \rightarrow D^0 \pi^+$. The $D^0$ is reconstructed in two decay channels: $D^0 \rightarrow K^-\pi^+$ and $D^0 \rightarrow K^-\pi^+\pi^-\pi^+$. We use Monte Carlo to simulate our reconstruction resolution in the difference of the reconstructed $D^{*+}$ and reconstructed $D^0$ masses. We fit a relativistic P-wave Breit-Wigner form convolved with the measured resolution, together with a background function, to the mass difference distribution. For the decay mode $D^0\rightarrow K^-\pi^+$ we obtain $\Gamma = 83.5 \pm 1.7 \pm 1.2$ keV and $\Delta m = m_{D^{* +}} - m_{D^0} = 145425.5 \pm 0.6 \pm 2.6$ keV, where the quoted errors are statistical and systematic, respectively. For the $D^0\rightarrow K^-\pi^+\pi^-\pi^+$ mode, we do not quote a width measurement at this time, but measure $\Delta m = m_{D^{* +}} - m_{D^0} = 145426.5 \pm 0.4 \pm 2.6 $ keV. Additionally, we present preliminary results from the decay mode $\Lambda_c (2880)^+ \rightarrow \Lambda_c^+\pi^+\pi^-$ for the mass, width and quasi-two-body branching ratios of the $\Lambda_c(2880)^+$ baryon. We measure $m(\Lambda_c(2880)^+) - m(\Lambda_c(2286)^+) = 594.9 \pm 0.4 \pm 0.3$ MeV and $\Gamma(\Lambda_c(2880)^+) = 6.2 \pm 1.4 \pm 1.5$ MeV, where the errors are statistical and systematic, respectively.