measurements

Our measurements of the and mass differences (concl:sc_comp) are competitive with the world's best measurements and our measurement of the $\scd - \scz$ mass difference is comparable in precision to the current world average.

concl:sc_comp  

Table 10.1: Comparison of measurements of and mass differences.

	Mass difference ()
Experiment	$\scd - \lc$	$\scz - \lc$	$\scd - \scz$
CLEO II [55]	$168.20 \pm 0.30 \pm 0.20$	$167.10 \pm 0.30 \pm 0.20$	$1.10 \pm 0.40 \pm 0.10$
E791 [56]	$167.76 \pm 0.29 \pm 0.15$	$167.38 \pm 0.29 \pm 0.15$	$0.38 \pm 0.40 \pm 0.15$
PDG avg. [4]	$167.87 \pm 0.20$	$167.31 \pm 0.21$	$0.66 \pm 0.28$
FOCUS	$\ensuremath{167.59}\xspace\pm \ensuremath{0.20}\xspace\pm \ensuremath{0.27}\xspace$	$\ensuremath{167.54}\xspace\pm \ensuremath{0.19}\xspace\pm \ensuremath{0.34}\xspace$	$\ensuremath{0.05}\xspace\pm \ensuremath{0.28}\xspace\pm \ensuremath{0.09}\xspace$

The measurements of mass differences (concl:scp_comp) complete the set of mass difference measurements and represent only the second measurement of the mass.

concl:scp_comp  

Table 10.2: Comparison of measurements of mass differences.

	Mass difference ()
Experiment	$\scp - \lc$	$\scp - \scz$
CLEO II [55]	$168.5 \pm 0.4 \pm 0.2$	$1.4 \pm 0.5 \pm 0.3$
World avg. [4]	$168.7 \pm 0.6$	$1.4 \pm 0.6$
FOCUS	$\ensuremath{168.03}\xspace\pm \ensuremath{1.01}\xspace\pm \ensuremath{0.30}\xspace$	$\ensuremath{0.49}\xspace\pm \ensuremath{1.03}\xspace\pm \ensuremath{0.45}\xspace$

No theoretical model accurately predicts all of the well measured baryon mass splittings. With experiments steadily improving these values, the disagreement with theoretical predictions is, in some cases, becoming more pronounced.

Our measurements of the and natural widths may be the first published measurements of these quantities. A preliminary measurement from another experiment is also available. These measurements are summarized in concl:sc_width. Unfortunately, these measurements are not of sufficient precision to discriminate between the various theoretical models.

 

Table 10.3: Comparison of measurements of widths.

concl:sc_width

	Width ()
Experiment	$\Gamma(\scd)$	$\Gamma(\scz)$
CLEO II1 [66]	$2.98 ^{+0.38}_{-0.35} \pm 0.50$	$2.63 ^{+0.36}_{-0.33} \pm 0.50$
World avg.	--	--
FOCUS	$2.53\xspace\pm 0.77\xspace\asserror{0.51}{0.56}$	$2.58\xspace\pm 0.79\xspace\asserror{0.51}{0.55}$

¹ Preliminary result