The and mass difference measurements presented here are competitive with the world's best measurements and will improve further when systematics due to the momentum scale are reduced. While the errors on the mass are larger than those from CLEO, a later analysis may be able to include other decay modes, thereby decreasing the statistical error. In order to reduce systematic uncertainties, it is instructive to have measurements of all three mass differences from a single experiment.
and Width Measurementssc_width
In this chapter, we present preliminary measurements of and which are compared with the existing theoretical predictions and a recent CLEO report . We find and . Low statistics and a width similar to the experimental resolution37 combine to make this a challenging measurement. These results are obtained with a sample of decays and decays.
Most theoretical predictions of are in the 1-3 range, as shown in sc_width:theory, which is in the measurement range of FOCUS. In sc_width:motivation we show that a comparison of the FOCUS and data suggests . This observation motivates further analysis. In sc_width:samples we discuss the reconstruction and simulation methods used in the analysis. In sc_width:method we explain the measurement and fitting methods and present preliminary values with statistical errors. sc_width:syst is concerned with various sources of possible systematic errors. In sc_width:validity we present two studies which shed light on particular problems which may occur with the measurement.