Our value in 2004, $2284.9$ $\pm0.6$ MeV, was the average of the measurements now filed below as “not used.” The BABAR measurement is so much better that we use it alone. Note that it is about 2.6 (old) standard deviations above the 2004 value.

The fit also includes ${{\mathit \Sigma}_{{{c}}}}-{{\mathit \Lambda}_{{{c}}}^{+}}$ and ${{\mathit \Lambda}_{{{c}}}^{*+}}-{{\mathit \Lambda}_{{{c}}}^{+}}$ mass-difference measurements, but this doesn't affect the ${{\mathit \Lambda}_{{{c}}}^{+}}$ mass. The new (in 2006) ${{\mathit \Lambda}_{{{c}}}^{+}}$ mass simply pushes all those other masses higher.

VALUE (MeV) EVTS DOCUMENT ID TECN  COMMENT $\bf{ 2286.46 \pm0.14}$ OUR FIT $2286.46$ $\pm0.14$ 4891 1 AUBERT,B 2005 S BABR ${{\mathit \Lambda}}{{\mathit K}_S^0}$ ${{\mathit K}^{+}}$ and ${{\mathit \Sigma}^{0}}{{\mathit K}_S^0}$ ${{\mathit K}^{+}}$ • • We do not use the following data for averages, fits, limits, etc. • • $2284.7$ $\pm0.6$ $\pm0.7$ 1134 AVERY 1991 CLEO Six modes $2281.7$ $\pm2.7$ $\pm2.6$ 29 ALVAREZ 1990 B NA14 ${{\mathit p}}{{\mathit K}^{-}}{{\mathit \pi}^{+}}$ $2285.8$ $\pm0.6$ $\pm1.2$ 101 BARLAG 1989 NA32 ${{\mathit p}}{{\mathit K}^{-}}{{\mathit \pi}^{+}}$ $2284.7$ $\pm2.3$ $\pm0.5$ 5 AGUILAR-BENIT.. 1988 B LEBC ${{\mathit p}}{{\mathit K}^{-}}{{\mathit \pi}^{+}}$ $2283.1$ $\pm1.7$ $\pm2.0$ 628 ALBRECHT 1988 C ARG ${{\mathit p}}{{\mathit K}^{-}}{{\mathit \pi}^{+}}$, ${{\mathit p}}{{\overline{\mathit K}}^{0}}$, ${{\mathit \Lambda}}$3 ${{\mathit \pi}}$ $2286.2$ $\pm1.7$ $\pm0.7$ 97 ANJOS 1988 B E691 ${{\mathit p}}{{\mathit K}^{-}}{{\mathit \pi}^{+}}$ $2281$ $\pm3$ 2 JONES 1987 HBC ${{\mathit p}}{{\mathit K}^{-}}{{\mathit \pi}^{+}}$ $2283$ $\pm3$ 3 BOSETTI 1982 HBC ${{\mathit p}}{{\mathit K}^{-}}{{\mathit \pi}^{+}}$ $2290$ $\pm3$ 1 CALICCHIO 1980 HYBR ${{\mathit p}}{{\mathit K}^{-}}{{\mathit \pi}^{+}}$ 1  AUBERT,B 2005S uses low-Q ${{\mathit \Lambda}}{{\mathit K}_S^0}$ ${{\mathit K}^{+}}$ and ${{\mathit \Sigma}^{0}}{{\mathit K}_S^0}$ ${{\mathit K}^{+}}$ decays to minimize systematic errors. The error above includes systematic as well as statistical errors. Many cross checks and adjustments to properties of the BABAR detector, as well as the large number of clean events, make this by far the best measurement of the ${{\mathit \Lambda}_{{{c}}}^{+}}$ mass.

References