#### ${{\mathit \Lambda}_{{c}}^{+}}$ MASS

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
 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
 1991
CLEO Six modes
$2281.7$ $\pm2.7$ $\pm2.6$ 29
 1990 B
NA14 ${{\mathit p}}{{\mathit K}^{-}}{{\mathit \pi}^{+}}$
$2285.8$ $\pm0.6$ $\pm1.2$ 101
 1989
NA32 ${{\mathit p}}{{\mathit K}^{-}}{{\mathit \pi}^{+}}$
$2284.7$ $\pm2.3$ $\pm0.5$ 5
 1988 B
LEBC ${{\mathit p}}{{\mathit K}^{-}}{{\mathit \pi}^{+}}$
$2283.1$ $\pm1.7$ $\pm2.0$ 628
 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
 1988 B
E691 ${{\mathit p}}{{\mathit K}^{-}}{{\mathit \pi}^{+}}$
$2281$ $\pm3$ 2
 1987
HBC ${{\mathit p}}{{\mathit K}^{-}}{{\mathit \pi}^{+}}$
$2283$ $\pm3$ 3
 1982
HBC ${{\mathit p}}{{\mathit K}^{-}}{{\mathit \pi}^{+}}$
$2290$ $\pm3$ 1
 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 ${{\mathit \Sigma}_{{c}}^{+}}$