Measuring Absolute Branching Ratios of Charmed Baryons in $B$ Decays

The $B$ factories are expected to provide huge samples of single $B$ decay events with little background by reconstructing one of the $B$ mesons produced in $\Upsilon (4S)$ decays. This represents a new experimental paradigm: such samples will allow to make measurements of a quality previously thought unrealistic. As example we discuss how absolute branching ratios for exclusive as well as inclusive charm baryon decays can be extracted. One starts out by observing decays like $B^- \to \bar p X$ as a signature for $B^- \to \Lambda _c \bar p X$ etc. and then exploits various correlations of the flavour of the $B$ meson with the baryon number of the (anti)proton and other observables like the charge of a lepton, baryon number of another baryon etc. An integrated luminosity of about 500 $fb^{-1}$ as could be available by 2005 should be sufficient for the task.