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:

AUBERT,B 2005S PR D72 052006 Precision Measurement of the ${{\mathit \Lambda}_{{c}}^{+}}$ Baryon Mass AVERY 1991 PR D43 3599 Inclusive Production of the Charmed Baryon ${{\mathit \Lambda}_{{c}}^{+}}$ from ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Annihilations at $\sqrt {s }$ = 10.55 GeV ALVAREZ 1990B PL B246 256 Photoproduction of the ${{\mathit \Lambda}_{{c}}}$ Charmed Baryon BARLAG 1989 PL B218 374 Precise Determination of the Lifetime of the Charmed Baryon ${{\mathit \Lambda}_{{c}}}$ AGUILAR-BENITEZ 1988B ZPHY C40 321 Charm Hadron Properties in 400 ${\mathrm {GeV/}}\mathit c$ ${{\mathit p}}{{\mathit p}}$ Interactions Also PL B189 254 Lifetime Measurement of ${{\mathit \Lambda}_{{c}}}$ Also PL B199 462 ${{\mathit \Lambda}_{{c}}^{+}}$ Production Characteristics in Proton Proton Interactions at 400 ${\mathrm {GeV/}}\mathit c$ Also SJNP 48 833 Lifetime Measurement of ${{\mathit \Lambda}_{{c}}}$ ALBRECHT 1988C PL B207 109 Observation of the Charmed Baryon ${{\mathit \Lambda}_{{c}}}$ in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Annihilation at 10 GeV ANJOS 1988B PRL 60 1379 Measurements of the ${{\mathit \Lambda}_{{c}}^{+}}$ Lifetime JONES 1987 ZPHY C36 593 Production of Charmed Hadrons in Neutrino Proton and Antineutrino Proton Charged Current Interactions BOSETTI 1982 PL 109B 234 Observation of a Doubly Charged Charmed Baryon in the Reaction ${{\mathit \nu}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit \mu}^{-}}{{\mathit \Sigma}_{{c}}^{++}}$ CALICCHIO 1980 PL 93B 521 First Observation of the Production and Decay of the ${{\mathit \Sigma}_{{c}}^{+}}$