# $\chi _{\boldsymbol b}$ AT HIGH ENERGY INSPIRE search

For a discussion of ${{\mathit B}}-{{\overline{\mathit B}}}$ mixing, see the note on ${{\mathit B}^{0}}-{{\overline{\mathit B}}^{0}}$ Mixing'' in the ${{\mathit B}^{0}}$ Particle Listings.

${{\mathit \chi}_{{b}}}$ is the average ${{\mathit B}}-{{\overline{\mathit B}}}$ mixing parameter at high-energy ${{\mathit \chi}_{{b}}}$= ${{\mathit f}_{{d}}^{\,'}}{{\mathit \chi}_{{d}}}{+}$ ${{\mathit f}_{{s}}^{\,'}}{{\mathit \chi}_{{s}}}$ where ${{\mathit f}_{{d}}^{\,'}}$ and ${{\mathit f}_{{s}}^{\,'}}$ are the fractions of ${{\mathit B}^{0}}$ and ${{\mathit B}_{{s}}^{0}}$ hadrons in an unbiased sample of semileptonic ${{\mathit b}}$-hadron decays.

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/. The averaging/rescaling procedure takes into account correlations between the measurements.

VALUE EVTS DOCUMENT ID TECN  COMMENT
$\bf{ 0.1284 \pm0.0069}$ OUR EVALUATION
$\bf{ 0.129 \pm0.004}$ OUR AVERAGE
$0.132$ $\pm0.001$ $\pm0.024$ 1
 2006 S
D0 ${{\mathit p}}{{\overline{\mathit p}}}$ at 1.96 TeV
$0.152$ $\pm0.007$ $\pm0.011$ 2
 2004 A
CDF ${{\mathit p}}{{\overline{\mathit p}}}$ at $1.8$ TeV
$0.1312$ $\pm0.0049$ $\pm0.0042$ 3
 2003 P
OPAL ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$
$0.127$ $\pm0.013$ $\pm0.006$ 4
 2001 L
DLPH ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$
$0.1192$ $\pm0.0068$ $\pm0.0051$ 5
 1999 D
L3 ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$
$0.121$ $\pm0.016$ $\pm0.006$ 6
 1994 J
DLPH ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$
$0.114$ $\pm0.014$ $\pm0.008$ 7
 1994 G
ALEP ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$
$0.129$ $\pm0.022$ 8
 1992 B
ALEP ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$
$0.176$ $\pm0.031$ $\pm0.032$ 1112 9
 1991 G
CDF ${{\mathit p}}{{\overline{\mathit p}}}$ $1.8$ TeV
$0.148$ $\pm0.029$ $\pm0.017$ 10
 1991 D
UA1 ${{\mathit p}}{{\overline{\mathit p}}}$ 630 GeV
• • • We do not use the following data for averages, fits, limits, etc. • • •
$0.131$ $\pm0.020$ $\pm0.016$ 11
 1997 I
CDF Repl. by ACOSTA 2004A
$0.1107$ $\pm0.0062$ $\pm0.0055$ 12
 1996
OPAL Rep. by ABBIENDI 2003P
$0.136$ $\pm0.037$ $\pm0.040$ 13
 1996
AMY ${{\mathit e}^{+}}{{\mathit e}^{-}}$ at $57.9$ GeV
$0.144$ $\pm0.014$ ${}^{+0.017}_{-0.011}$ 14
 1994 F
DLPH Sup. by ABREU 1994J
$0.131$ $\pm0.014$ 15
 1994 J
DLPH ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$
$0.123$ $\pm0.012$ $\pm0.008$
 1994 D
L3 Repl. by ACCIARRI 1999D
$0.157$ $\pm0.020$ $\pm0.032$ 16
 1994
UA1 $\sqrt {\mathit s }$ = 630 GeV
$0.121$ ${}^{+0.044}_{-0.040}$ $\pm0.017$ 1665 17
 1993 C
DLPH Sup. by ABREU 1994J
$0.143$ ${}^{+0.022}_{-0.021}$ $\pm0.007$ 18
 1993 B
OPAL Sup. by ALEXANDER 1996
$0.145$ ${}^{+0.041}_{-0.035}$ $\pm0.018$ 19
 1992 C
OPAL ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$
$0.121$ $\pm0.017$ $\pm0.006$ 20
 1992 C
L3 Sup. by ACCIARRI 1994D
$0.132$ $\pm0.22$ ${}^{+0.015}_{-0.012}$ 823 21
 1991
ALEP ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$
$0.178$ ${}^{+0.049}_{-0.040}$ $\pm0.020$ 22
 1990 P
L3 ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$
$0.17$ ${}^{+0.15}_{-0.08}$ 23, 24
 1990
MRK2 ${{\mathit e}^{+}}{{\mathit e}^{-}}$ 29 GeV
$0.21$ ${}^{+0.29}_{-0.15}$ 23
 1988
MAC ${\it{}E}^{\it{}ee}_{\rm{}cm}$= 29 GeV
$>0.02 at 90\%\mathit CL$ 23
 1988
MAC ${\it{}E}^{\it{}ee}_{\rm{}cm}$= 29 GeV
$0.121$ $\pm0.047$ 25, 23
 1987 C
UA1 Repl. by ALBAJAR 1991D
$<0.12 at 90\%\mathit CL$ 26, 23
 1985
MRK2 ${\it{}E}^{\it{}ee}_{\rm{}cm}$= 29 GeV
1  Uses the dimuon charge asymmetry. Averaged over the mix of ${{\mathit b}}$-flavored hadrons.
2  Measurement performed using events containing a dimuon or an ${{\mathit e}}/{{\mathit \mu}}$ pair.
3  The average ${{\mathit B}}$ mixing parameter is determined simultaneously with ${{\mathit b}}$ and ${{\mathit c}}$ forward-backward asymmetries in the fit.
4  The experimental systematic and model uncertainties are combined in quadrature.
5  ACCIARRI 1999D uses maximum-likelihood fits to extract ${{\mathit \chi}_{{b}}}$ as well as the $\mathit A{}^{{{\mathit b}}}_{\mathit FB}$ in ${{\mathit Z}}$ $\rightarrow$ ${{\mathit b}}{{\overline{\mathit b}}}$ events containing prompt leptons.
6  This ABREU 1994J result is from 5182 ${{\mathit \ell}}{{\mathit \ell}}$ and 279 ${{\mathit \Lambda}}{{\mathit \ell}}$ events. The systematic error includes $0.004$ for model dependence.
7  BUSKULIC 1994G data analyzed using ${{\mathit e}}{{\mathit e}}$ , ${{\mathit e}}{{\mathit \mu}}$ , and ${{\mathit \mu}}{{\mathit \mu}}$ events.
8  BUSKULIC 1992B uses a jet charge technique combined with electrons and muons.
9  ABE 1991G measurement of $\chi$ is done with ${{\mathit e}}{{\mathit \mu}}$ and ${{\mathit e}}{{\mathit e}}$ events.
10  ALBAJAR 1991D measurement of $\chi$ is done with dimuons.
11  Uses di-muon events.
12  ALEXANDER 1996 uses a maximum likelihood fit to simultaneously extract ${{\mathit \chi}}$ as well as the forward-backward asymmetries in ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$ $\rightarrow$ ${{\mathit b}}{{\overline{\mathit b}}}$ and ${{\mathit c}}{{\overline{\mathit c}}}$ .
13  UENO 1996 extracted $\chi$ from the energy dependence of the forward-backward asymmetry.
14  ABREU 1994F uses the average electric charge sum of the jets recoiling against a ${{\mathit b}}$-quark jet tagged by a high $\mathit p_{\mathit T}$ muon. The result is for ${{\overline{\mathit \chi}}}$ = ${{\mathit f}_{{d}}}{{\mathit \chi}_{{d}}}$ $+0.9$ ${{\mathit f}_{{s}}}{{\mathit \chi}_{{s}}}$ .
15  This ABREU 1994J result combines ${{\mathit \ell}}{{\mathit \ell}}$ , ${{\mathit \Lambda}}{{\mathit \ell}}$ , and jet-charge ${{\mathit \ell}}$ (ABREU 1994F) analyses. It is for ${{\overline{\mathit \chi}}}$ = $\mathit f_{\mathit d}{{\mathit \chi}_{{d}}}+0.96\mathit f_{\mathit s}{{\mathit \chi}_{{s}}}$.
16  ALBAJAR 1994 uses dimuon events. Not independent of ALBAJAR 1991D.
17  ABREU 1993C data analyzed using ${{\mathit e}}{{\mathit e}}$ , ${{\mathit e}}{{\mathit \mu}}$ , and ${{\mathit \mu}}{{\mathit \mu}}$ events.
18  AKERS 1993B analysis performed using dilepton events.
19  ACTON 1992C uses electrons and muons. Superseded by AKERS 1993B.
20  ADEVA 1992C uses electrons and muons.
21  DECAMP 1991 done with opposite and like-sign dileptons. Superseded by BUSKULIC 1992B.
22  ADEVA 1990P measurement uses ${{\mathit e}}{{\mathit e}}$ , ${{\mathit \mu}}{{\mathit \mu}}$ , and ${{\mathit e}}{{\mathit \mu}}$ events from 118k events at the ${{\mathit Z}}$. Superseded by ADEVA 1992C.
23  These experiments are not in the average because the combination of ${{\mathit B}_{{s}}}$ and ${{\mathit B}_{{d}}}$ mesons which they see could differ from those at higher energy.
24  The WEIR 1990 measurement supersedes the limit obtained in SCHAAD 1985 . The 90$\%$ CL are $0.06$ and $0.38$.
25  ALBAJAR 1987C measured $\chi$ = ( ${{\overline{\mathit B}}^{0}}$ $\rightarrow$ ${{\mathit B}^{0}}$ $\rightarrow$ ${{\mathit \mu}^{+}}$ X) divided by the average production weighted semileptonic branching fraction for ${{\mathit B}}$ hadrons at 546 and 630 GeV.
26  Limit is average probability for hadron containing ${{\mathit B}}$ quark to produce a positive lepton.
References:
 ABAZOV 2006S
PR D74 092001 Measurement of the $\mathit CP$-violation Parameter of ${{\mathit B}^{0}}$ Mixing and Decay with ${{\mathit p}}$ ${{\overline{\mathit p}}}$ $\rightarrow$ ${{\mathit \mu}}{{\mathit \mu}}{{\mathit X}}$ Data
 ACOSTA 2004A
PR D69 012002 Measurement of the Average Time-Integrated Mixing Probability of ${\mathit {\mathit b}}$-Flavored Hadrons Produced at the Tevatron
 ABBIENDI 2003P
PL B577 18 Measurement of Heavy Quark Forward Backward Asymmetries and Average ${{\mathit B}}$ Mixing using Leptons in Hadronic ${{\mathit Z}}$ Decays
 ABREU 2001L
EPJ C20 455 Measurement of the Semileptonic ${\mathit {\mathit b}}$ Branching Fractions and Average ${\mathit {\mathit b}}$ Mixing Parameter in ${{\mathit Z}}$ Decays
 ACCIARRI 1999D
PL B448 152 Measurement of the ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$ $\rightarrow$ ${\mathit {\mathit b}}$ ${\mathit {\overline{\mathit b}}}$ Forward Backward Asymmetry and the ${{\mathit B}^{0}}{{\overline{\mathit B}}^{0}}$ Mixing Parameter using Prompt Leptons
 ABE 1997I
PR D55 2546 Measurement of ${\mathit {\mathit b}}{\mathit {\overline{\mathit b}}}$ Production Correlations, ${{\mathit B}^{0}}{{\overline{\mathit B}}^{0}}$ Mixing, and a Limit on ${{\mathit \epsilon}_{{b}}}$ in ${{\mathit p}}{{\overline{\mathit p}}}$ Collisions at $\sqrt {s }$ = 1.8 TeV
 ALEXANDER 1996
ZPHY C70 357 Measurement of the Heavy Quark Forward Backward Asymmetries and Average ${{\mathit B}}$ Mixing using Leptons in MultiHadronic Events
 UENO 1996
PL B381 365 Measurement of the Forward Backward Asymmetry in ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${\mathit {\mathit b}}$ ${\mathit {\overline{\mathit b}}}$ and the ${\mathit {\mathit b}}$ Quark Branching Ratio to Muons at TRISTAN using Neural Networks
 ABREU 1994F
PL B322 459 Measurement of the ${{\mathit B}^{0}}−{{\overline{\mathit B}}^{0}}$ Mixing using the Average Electric Charge of Hadron-Jets in ${{\mathit Z}^{0}}$ Decays
 ABREU 1994J
PL B332 488 Measurement of the ${{\mathit B}^{0}}{{\overline{\mathit B}}^{0}}$ Mixing Parameter in DELPHI
 ACCIARRI 1994D
PL B335 542 Measurement of the ${{\mathit B}^{0}}$ $\leftrightarrow$ ${{\overline{\mathit B}}^{0}}$ Mixing Parameter and the ${{\mathit Z}}$ $\rightarrow$ ${\mathit {\mathit b}}$ ${\mathit {\overline{\mathit b}}}$ Forward-Backward Asymmetry
 ALBAJAR 1994
ZPHY C61 41 Measurement of ${\mathit {\mathit b}}{\mathit {\overline{\mathit b}}}$ Correlations at the CERN ${{\mathit p}}{{\overline{\mathit p}}}$ Collider
 BUSKULIC 1994G
ZPHY C62 179 Heavy Flavor Production and Decay with Prompt Leptons in the ALEPH Detector
 ABREU 1993C
PL B301 145 A Study of ${{\mathit B}^{0}}{{\overline{\mathit B}}^{0}}$ Mixing Using Semileptonic Decays of ${{\mathit B}}$ Hadrons Produced from ${{\mathit Z}^{0}}$
 AKERS 1993B
ZPHY C60 199 Measurements of ${{\mathit B}^{0}}−{{\overline{\mathit B}}^{0}}$ Mixing, $\Gamma\mathrm {( {{\mathit Z}^{0}} \rightarrow {\mathit {\mathit b}} {\mathit {\overline{\mathit b}}})}/\Gamma\mathrm {( {{\mathit Z}^{0}} \rightarrow hadrons)}$ and Semileptonic Branching Ratios for ${{\mathit b}}$-Flavored Hadrons in Hadronic ${{\mathit Z}^{0}}$ Decays
 ACTON 1992C
PL B276 379 Measurement of ${{\mathit B}^{0}}{{\overline{\mathit B}}^{0}}$ Mixing in Hadronic ${{\mathit Z}^{0}}$ Decays
PL B288 395 An Improved Measurement of ${{\mathit B}^{0}}−{{\overline{\mathit B}}^{0}}$ Mixing in ${{\mathit Z}^{0}}$ Decays
 BUSKULIC 1992B
PL B284 177 Measurement of ${{\mathit B}^{0}}$ $\leftrightarrow$ ${{\overline{\mathit B}}^{0}}$ Mixing at the ${{\mathit Z}}$ Using a Jet Charge Method
 ABE 1991G
PRL 67 3351 Measurement of ${{\mathit B}^{0}}{{\overline{\mathit B}}^{0}}$ Mixing at the Fermilab Tevatron Collider
 ALBAJAR 1991D
PL B262 171 Measurement of ${{\mathit B}^{0}}$ $\leftrightarrow$ ${{\overline{\mathit B}}^{0}}$ Mixing at the CERN S${{\mathit p}}{{\overline{\mathit p}}}$S Collider
 DECAMP 1991
PL B258 236 Measurement of ${{\mathit B}}$ $−$ ${{\overline{\mathit B}}}$ Mixing at the ${{\mathit Z}^{0}}$
PL B252 703 A Measurement of ${{\mathit B}^{0}}{{\overline{\mathit B}}^{0}}$ Mixing in ${{\mathit Z}^{0}}$ Decays
PL B240 289 A Reanalysis of ${{\mathit B}^{0}}$ $−$ ${{\overline{\mathit B}}^{0}}$ Mixing in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Annihilation at 29 GeV
PL B200 221 Additional Evidence for ${{\mathit B}^{0}}$ $−$ ${{\overline{\mathit B}}^{0}}$ Mixing
PL B186 247 Search for ${{\mathit B}^{0}}-{{\overline{\mathit B}}^{0}}$ Oscillations at the CERN Proton Antiproton Collider. Paper 2
PL 160B 188 Upper Limit on ${{\mathit B}^{0}}{{\overline{\mathit B}}^{0}}$ Mixing in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Annihilation at 29 GeV
ZPHY C72 365 A Precise Measurement of the ${{\mathit \tau}}$ Polarization and Its Forward Backward Asymmetry at LEP