${{\boldsymbol B}^{\pm}}/{{\boldsymbol B}^{0}}/{{\boldsymbol B}_{{s}}^{0}}/{{\boldsymbol b}}$-baryon ADMIXTURE MEAN LIFE INSPIRE search

Each measurement of the ${{\mathit B}}$ mean life is an average over an admixture of various bottom mesons and baryons which decay weakly. Different techniques emphasize different admixtures of produced particles, which could result in a different ${{\mathit B}}~$mean life.

``OUR EVALUATION'' is an average using rescaled values of the data listed below. The average and rescaling were performed by the Heavy Flavor Averaging Group (HFLAV) and are described at http://www.slac.stanford.edu/xorg/hflav/. This is a weighted average of the lifetimes of the five main ${{\mathit b}}$-hadron species (${{\mathit B}^{+}}$, ${{\mathit B}^{0}}$, ${{\mathit B}_{{sH}}^{0}}$, ${{\mathit B}_{{sL}}^{0}}$, and ${{\mathit \Lambda}_{{b}}}$) that assumes the production fractions in ${{\mathit Z}}$ decays (given at the end of this section) and equal production fractions of ${{\mathit B}_{{sH}}^{0}}$ and ${{\mathit B}_{{sL}}^{0}}$ mesons.
VALUE ($ 10^{-12} $ s) EVTS DOCUMENT ID TECN  COMMENT
$\bf{ 1.5662 \pm0.0029}$ OUR EVALUATION
• • • We do not use the following data for averages, fits, limits, etc. • • •
$1.570$ $\pm0.005$ $\pm0.008$ 1
ABDALLAH
2004E
DLPH ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$
$1.533$ $\pm0.015$ ${}^{+0.035}_{-0.031}$ 2
ABE
1998B
CDF ${{\mathit p}}{{\overline{\mathit p}}}$ at $1.8$ TeV
$1.549$ $\pm0.009$ $\pm0.015$ 3
ACCIARRI
1998
L3 ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$
$1.611$ $\pm0.010$ $\pm0.027$ 4
ACKERSTAFF
1997F
OPAL ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$
$1.582$ $\pm0.011$ $\pm0.027$ 4
ABREU
1996E
DLPH ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$
$1.575$ $\pm0.010$ $\pm0.026$ 5
ABREU
1996E
DLPH ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$
$1.533$ $\pm0.013$ $\pm0.022$ 19.8k 6
BUSKULIC
1996F
ALEP ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$
$1.564$ $\pm0.030$ $\pm0.036$ 7
ABE,K
1995B
SLD ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$
$1.542$ $\pm0.021$ $\pm0.045$ 8
ABREU
1994L
DLPH ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$
$1.50$ ${}^{+0.24}_{-0.21}$ $\pm0.03$ 9
ABREU
1994P
DLPH ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$
$1.46$ $\pm0.06$ $\pm0.06$ 5344 10
ABE
1993J
CDF Repl. by ABE 1998B
$1.23$ ${}^{+0.14}_{-0.13}$ $\pm0.15$ 188 11
ABREU
1993D
DLPH Sup. by ABREU 1994L
$1.49$ $\pm0.11$ $\pm0.12$ 253 12
ABREU
1993G
DLPH Sup. by ABREU 1994L
$1.51$ ${}^{+0.16}_{-0.14}$ $\pm0.11$ 130 13
ACTON
1993C
OPAL ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$
$1.523$ $\pm0.034$ $\pm0.038$ 5372 14
ACTON
1993L
OPAL ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$
$1.535$ $\pm0.035$ $\pm0.028$ 7357 14
ADRIANI
1993K
L3 Repl. by ACCIARRI 1998
$1.511$ $\pm0.022$ $\pm0.078$ 15
BUSKULIC
1993O
ALEP ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$
$1.28$ $\pm0.10$ 16
ABREU
1992
DLPH Sup. by ABREU 1994L
$1.37$ $\pm0.07$ $\pm0.06$ 1354 17
ACTON
1992
OPAL Sup. by ACTON 1993L
$1.49$ $\pm0.03$ $\pm0.06$ 18
BUSKULIC
1992F
ALEP Sup. by BUSKULIC 1996F
$1.35$ ${}^{+0.19}_{-0.17}$ $\pm0.05$ 19
BUSKULIC
1992G
ALEP ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$
$1.32$ $\pm0.08$ $\pm0.09$ 1386 20
ADEVA
1991H
L3 Sup. by ADRIANI 1993K
$1.32$ ${}^{+0.31}_{-0.25}$ $\pm0.15$ 37 21
ALEXANDER
1991G
OPAL ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$
$1.29$ $\pm0.06$ $\pm0.10$ 2973 22
DECAMP
1991C
ALEP Sup. by BUSKULIC 1992F
$1.36$ ${}^{+0.25}_{-0.23}$ 23
HAGEMANN
1990
JADE ${\it{}E}^{\it{}ee}_{\rm{}cm}$= 35 GeV
$1.13$ $\pm0.15$ 24
LYONS
1990
RVUE
$1.35$ $\pm0.10$ $\pm0.24$
BRAUNSCHWEIG
1989B
TASS ${\it{}E}^{\it{}ee}_{\rm{}cm}$= 35 GeV
$0.98$ $\pm0.12$ $\pm0.13$
ONG
1989
MRK2 ${\it{}E}^{\it{}ee}_{\rm{}cm}$= 29 GeV
$1.17$ ${}^{+0.27}_{-0.22}$ ${}^{+0.17}_{-0.16}$
KLEM
1988
DLCO ${\it{}E}^{\it{}ee}_{\rm{}cm}$= 29 GeV
$1.29$ $\pm0.20$ $\pm0.21$ 25
ASH
1987
MAC ${\it{}E}^{\it{}ee}_{\rm{}cm}$= 29 GeV
$1.02$ ${}^{+0.42}_{-0.39}$ 301 26
BROM
1987
HRS ${\it{}E}^{\it{}ee}_{\rm{}cm}$= 29 GeV
1  Measurement performed using an inclusive reconstruction and ${{\mathit B}}$ flavor identification technique.
2  Measured using inclusive ${{\mathit J / \psi}{(1S)}}$ $\rightarrow$ ${{\mathit \mu}^{+}}{{\mathit \mu}^{-}}$ vertex.
3  ACCIARRI 1998 uses inclusively reconstructed secondary vertex and lepton impact parameter.
4  ACKERSTAFF 1997F uses inclusively reconstructed secondary vertices.
5  Combines ABREU 1996E secondary vertex result with ABREU 1994L impact parameter result.
6  BUSKULIC 1996F analyzed using 3D impact parameter.
7  ABE,K 1995B uses an inclusive topological technique.
8  ABREU 1994L uses charged particle impact parameters. Their result from inclusively reconstructed secondary vertices is superseded by ABREU 1996E.
9  From proper time distribution of ${{\mathit b}}$ $\rightarrow$ ${{\mathit J / \psi}{(1S)}}$ anything.
10  ABE 1993J analyzed using ${{\mathit J / \psi}{(1S)}}$ $\rightarrow$ ${{\mathit \mu}}{{\mathit \mu}}$ vertices.
11  ABREU 1993D data analyzed using ${{\mathit D}}$ / ${{\mathit D}^{*}}{{\mathit \ell}}$ anything event vertices.
12  ABREU 1993G data analyzed using charged and neutral vertices.
13  ACTON 1993C analysed using ${{\mathit D}}$ / ${{\mathit D}^{*}}{{\mathit \ell}}$ anything event vertices.
14  ACTON 1993L and ADRIANI 1993K analyzed using lepton (${{\mathit e}}$ and ${{\mathit \mu}}$) impact parameter at ${{\mathit Z}}$.
15  BUSKULIC 1993O analyzed using dipole method.
16  ABREU 1992 is combined result of muon and hadron impact parameter analyses. Hadron tracks gave ($12.7$ $\pm0.4$ $\pm1.2){\times }10^{-13}~$s for an admixture of ${{\mathit B}}$ species weighted by production fraction and mean charge multiplicity, while muon tracks gave ($13.0$ $\pm1.0$ $\pm0.8){\times }10^{-13}~$s for an admixture weighted by production fraction and semileptonic branching fraction.
17  ACTON 1992 is combined result of muon and electron impact parameter analyses.
18  BUSKULIC 1992F uses the lepton impact parameter distribution for data from the 1991 run.
19  BUSKULIC 1992G use ${{\mathit J / \psi}{(1S)}}$ tags to measure the average ${{\mathit b}}$ lifetime. This is comparable to other methods only if the ${{\mathit J / \psi}{(1S)}}$ branching fractions of the different ${{\mathit b}}$-flavored hadrons are in the same ratio.
20  Using ${{\mathit Z}}$ $\rightarrow$ ${{\mathit e}^{+}}$ X or ${{\mathit \mu}^{+}}$ X, ADEVA 1991H determined the average lifetime for an admixture of ${{\mathit B}}$ hadrons from the impact parameter distribution of the lepton.
21  Using ${{\mathit Z}}$ $\rightarrow$ ${{\mathit J / \psi}{(1S)}}$ X, ${{\mathit J / \psi}{(1S)}}$ $\rightarrow$ ${{\mathit \ell}^{+}}{{\mathit \ell}^{-}}$ , ALEXANDER 1991G determined the average lifetime for an admixture of ${{\mathit B}}$ hadrons from the decay point of the ${{\mathit J / \psi}{(1S)}}$.
22  Using ${{\mathit Z}}$ $\rightarrow$ ${{\mathit e}}$ X or ${{\mathit \mu}}$ X, DECAMP 1991C determines the average lifetime for an admixture of ${{\mathit B}}$ hadrons from the signed impact parameter distribution of the lepton.
23  HAGEMANN 1990 uses electrons and muons in an impact parameter analysis.
24  LYONS 1990 combine the results of the ${{\mathit B}}$ lifetime measurements of ONG 1989 , BRAUNSCHWEIG 1989B, KLEM 1988 , and ASH 1987 , and JADE data by private communication. They use statistical techniques which include variation of the error with the mean life, and possible correlations between the systematic errors. This result is not independent of the measured results used in our average.
25  We have combined an overall scale error of 15$\%$ in quadrature with the systematic error of $\pm0.7$ to obtain $\pm2.1$ systematic error.
26  Statistical and systematic errors were combined by BROM 1987 .
  References:
ABDALLAH 2004E
EPJ C33 307 A Precise Measurement of the ${{\mathit B}^{+}}$, ${{\mathit B}^{0}}$ and Mean b-hadron Lifetime with the DELPHI Detector at LEP I
ABE 1998B
PR D57 5382 Measurement of ${{\mathit B}}$ Hadron Lifetimes using ${{\mathit J / \psi}}$ Final States at CDF
ACCIARRI 1998
PL B416 220 Measurement of the Average Lifetime of ${{\mathit b}}$-Hadrons in ${{\mathit Z}}$ Decays
ACKERSTAFF 1997F
ZPHY C73 397 A Measurement of the Average Bottom Hadron Lifetime
ABREU 1996E
PL B377 195 Updated Precision Measurement of the Average Lifetime of ${{\mathit B}}$ Hadrons
BUSKULIC 1996F
PL B369 151 A Precise Measurement of the Average ${\mathit {\mathit b}}$ Hadron Lifetime
ABE,K 1995B
PRL 75 3624 Measurement of the Average ${{\mathit B}}$ Hadron Lifetime in ${{\mathit Z}^{0}}$ Decays using Reconstructed Vertices
ABREU 1994L
ZPHY C63 3 A Precision Measurement of the Average Lifetime of ${{\mathit B}}$ Hadrons
ABREU 1994P
PL B341 109 ${{\mathit J / \psi}}$ Production in the Hadronic Decays of the ${{\mathit Z}}$
ABE 1993J
PRL 71 3421 Measurement of the Average Lifetime of ${{\mathit B}}$ Hadrons Produced in ${{\mathit p}}{{\overline{\mathit p}}}$ Collisions at $\sqrt {s }$ = 1.8 TeV
ABREU 1993G
PL B312 253 A Measurement of the Mean Lifetimes of Charged and Neutral ${{\mathit B}}$ Hadrons
ABREU 1993D
ZPHY C57 181 A Measurement of ${{\mathit B}}$ Meson Production and Lifetime using ${{\mathit D}}{{\mathit \ell}^{-}}$ Events in ${{\mathit Z}^{0}}$ Decays
ACTON 1993C
PL B307 247 Measurement of the ${{\mathit B}^{0}}$ and ${{\mathit B}^{+}}$ Lifetime
ACTON 1993L
ZPHY C60 217 Measurement of the Average ${\mathit {\mathit b}}$ Hadron Lifetime in ${{\mathit Z}^{0}}$ Decays
ADRIANI 1993K
PL B317 474 Measurement of the Average Lifetime of ${{\mathit b}}$ Hadrons
BUSKULIC 1993O
PL B314 459 Measurement of the ${\mathit {\mathit b}}$ Hadron Lifetime with the Dipole Method
ABREU 1992
ZPHY C53 567 Measurement of the Average Lifetime of ${{\mathit B}}$ Hadrons
ACTON 1992
PL B274 513 Measurement of the Average ${{\mathit B}}$ Hadron Lifetime in ${{\mathit Z}^{0}}$ Decays
BUSKULIC 1992F
PL B295 174 Updated Measurement of the Average ${\mathit {\mathit b}}$ Hadron Lifetime
BUSKULIC 1992G
PL B295 396 Measurement of Mean Lifetime and Branching Fractions of ${\mathit {\mathit b}}$ Hadrons Decaying to ${{\mathit J / \psi}}$
ADEVA 1991H
PL B270 111 Measurement of the Lifetime of ${{\mathit B}}$ Hadrons and a Determination of |$\mathit V_{cb}$|
ALEXANDER 1991G
PL B266 485 Observation of ${{\mathit J / \psi}}$ Production in Multihadronic ${{\mathit Z}^{0}}$ Decays
DECAMP 1991C
PL B257 492 Measurement of the ${{\mathit B}}$ Hadron Lifetime
HAGEMANN 1990
ZPHY C48 401 A Measurement of the Average Lifetime of ${{\mathit B}}$ Hadrons Produced by ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Collisions at $\sqrt {s }$ = 36.3 GeV
LYONS 1990
PR D41 982 On the Determination of the B Lifetime by Combining the Results of Different Experiments
BRAUNSCHWEIG 1989B
ZPHY C44 1 Measurement of the Average Lifetime of ${{\mathit B}}$ Hadrons
ONG 1989
PRL 62 1236 A Refined Measurement of the ${{\mathit B}}$ Hadron Lifetime
KLEM 1988
PR D37 41 An Improved Measurement of the Average Lifetime of Hadrons Containing Bottom Quarks
ASH 1987
PRL 58 640 Determination of the Lifetime of Bottom Hadrons
BROM 1987
PL B195 301 Measurement of the Lifetime of Hadrons Containing the ${\mathit {\mathit b}}$-Quark