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${{\mathit b}}$-baryon ADMIXTURE MEAN LIFE

INSPIRE   PDGID:

S061T

Each measurement of the ${{\mathit b}}$-baryon mean life is an average over an admixture of various ${{\mathit b}}~$baryons which decay weakly. Different techniques emphasize different admixtures of produced particles, which could result in a different ${{\mathit b}}$-baryon mean life. More ${{\mathit b}}$-baryon flavor specific channels are not included in the measurement.

VALUE ($ 10^{-12} $ s) EVTS DOCUMENT ID TECN  COMMENT • • We do not use the following data for averages, fits, limits, etc. • • $1.218$ ${}^{+0.130}_{-0.115}$ $\pm0.042$ 1 ABAZOV 2007 S D0 Repl. by ABAZOV 2012U $1.22$ ${}^{+0.22}_{-0.18}$ $\pm0.04$ 1 ABAZOV 2005 C D0 Repl. by ABAZOV 2007S $1.16$ $\pm0.20$ $\pm0.08$ 2 ABREU 1999 W DLPH ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$ $1.19$ $\pm0.14$ $\pm0.07$ 3 ABREU 1999 W DLPH ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$ $1.14$ $\pm0.08$ $\pm0.04$ 4 ABREU 1999 W DLPH ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$ $1.11$ ${}^{+0.19}_{-0.18}$ $\pm0.05$ 5 ABREU 1999 W DLPH ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$ $1.29$ ${}^{+0.24}_{-0.22}$ $\pm0.06$ 5 ACKERSTAFF 1998 G OPAL ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$ $1.20$ $\pm0.08$ $\pm0.06$ 6 BARATE 1998 D ALEP ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$ $1.21$ $\pm0.11$ 5 BARATE 1998 D ALEP ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$ $1.32$ $\pm0.15$ $\pm0.07$ 7 ABE 1996 M CDF ${{\mathit p}}{{\overline{\mathit p}}}$ at 1.8 TeV $1.46$ ${}^{+0.22}_{-0.21}$ ${}^{+0.07}_{-0.09}$ ABREU 1996 D DLPH Repl. by ABREU 1999W $1.10$ ${}^{+0.19}_{-0.17}$ $\pm0.09$ 5 ABREU 1996 D DLPH ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$ $1.16$ $\pm0.11$ $\pm0.06$ 5 AKERS 1996 OPAL ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$ $1.27$ ${}^{+0.35}_{-0.29}$ $\pm0.09$ ABREU 1995 S DLPH Repl. by ABREU 1999W $1.05$ ${}^{+0.12}_{-0.11}$ $\pm0.09$ 290 BUSKULIC 1995 L ALEP Repl. by BARATE 1998D $1.04$ ${}^{+0.48}_{-0.38}$ $\pm0.10$ 11 8 ABREU 1993 F DLPH Excess ${{\mathit \Lambda}}{{\mathit \mu}^{-}}$ , decay lengths $1.05$ ${}^{+0.23}_{-0.20}$ $\pm0.08$ 157 9 AKERS 1993 OPAL Excess ${{\mathit \Lambda}}{{\mathit \ell}^{-}}$ , decay lengths $1.12$ ${}^{+0.32}_{-0.29}$ $\pm0.16$ 101 10 BUSKULIC 1992 I ALEP Excess ${{\mathit \Lambda}}{{\mathit \ell}^{-}}$ , impact parameters 1  Measured mean life using fully reconstructed ${{\mathit \Lambda}_{{b}}^{0}}$ $\rightarrow$ ${{\mathit J / \psi}}{{\mathit \Lambda}}$ decays. 2  Measured using ${{\mathit \Lambda}}{{\mathit \ell}^{-}}$ decay length. 3  Measured using ${{\mathit p}}{{\mathit \ell}^{-}}$ decay length. 4  This ABREU 1999W result is the combined result of the ${{\mathit \Lambda}}{{\mathit \ell}^{-}}$ , ${{\mathit p}}{{\mathit \ell}^{-}}$ , and excess ${{\mathit \Lambda}}{{\mathit \mu}^{-}}$ impact parameter measurements. 5  Measured using ${{\mathit \Lambda}_{{c}}}{{\mathit \ell}^{-}}$ and ${{\mathit \Lambda}}{{\mathit \ell}^{+}}{{\mathit \ell}^{-}}$ . 6  Measured using the excess of ${{\mathit \Lambda}}{{\mathit \ell}^{-}}$ , lepton impact parameter. 7  Measured using ${{\mathit \Lambda}_{{c}}}{{\mathit \ell}^{-}}$ . 8  ABREU 1993F superseded by ABREU 1996D. 9  AKERS 1993 superseded by AKERS 1996 . 10  BUSKULIC 1992I superseded by BUSKULIC 1995L.

References:

ABAZOV 2007S PRL 99 142001 Measurement of the ${{\mathit \Lambda}_{{b}}}$ Lifetime in the Exclusive Decay ${{\mathit \Lambda}_{{b}}}$ $\rightarrow$ ${{\mathit J / \psi}}{{\mathit \Lambda}}$ ABAZOV 2005C PRL 94 102001 Measurement of the ${{\mathit \Lambda}_{{b}}^{0}}$ Lifetime in the Decay $\rightarrow$ ${{\mathit J / \psi}}{{\mathit \Lambda}^{0}}$ with the ${D0}$ Detector ABREU 1999W EPJ C10 185 Measurement of the Lifetime of ${\mathit {\mathit b}}$ Baryons ACKERSTAFF 1998G PL B426 161 Measurements of the ${{\mathit B}_{{s}}}$ and ${{\mathit \Lambda}_{{b}}}$ Lifetimes BARATE 1998D EPJ C2 197 Measurement of the ${\mathit {\mathit b}}$ Baryon Lifetime and Branching Fractions in ${{\mathit Z}}$ Decays ABE 1996M PRL 77 1439 Measurement of ${{\mathit \Lambda}_{{b}}^{0}}$ Lifetime using ${{\mathit \Lambda}_{{b}}^{0}}$ $\rightarrow$ ${{\mathit \Lambda}_{{c}}^{+}}{{\mathit \ell}^{-}}{{\overline{\mathit \nu}}}$ ABREU 1996D ZPHY C71 199 Determination of the Average Lifetime of ${{\mathit b}}$-Baryons AKERS 1996 ZPHY C69 195 Measurement of the Average ${\mathit {\mathit b}}$-Baryon Lifetime and the Product Branching Ratio f(${\mathit {\mathit b}}$ $\rightarrow$ ${{\mathit \Lambda}_{{b}}})\cdot{}$B( ${{\mathit \Lambda}_{{b}}}$ $\rightarrow$ ${{\mathit \Lambda}}{{\mathit \ell}^{-}}{{\mathit \nu}}{{\mathit X}}$ ) ABREU 1995S ZPHY C68 375 Lifetime and Production Rate of Beauty Baryons from ${{\mathit Z}}$ Decays BUSKULIC 1995L PL B357 685 Measurements of the ${{\mathit b}}$ Baryon Lifetime ABREU 1993F PL B311 379 Measurement of ${{\mathit \Lambda}_{{b}}}$ Production and Lifetime in ${{\mathit Z}^{0}}$ Hadronic Decays AKERS 1993 PL B316 435 A Measurement of the Average Lifetime of ${{\mathit b}}$-Flavored Baryons Also PL B281 394 Evidence for ${\mathit {\mathit b}}$-Flavored Baryon Production in ${{\mathit Z}^{0}}$ Decays at LEP BUSKULIC 1992I PL B297 449 A Measurement of the ${\mathit {\mathit b}}$ Baryon Lifetime Also PL B278 209 Evidence for ${\mathit {\mathit b}}$ Baryons in ${{\mathit Z}}$ Decays