$\chi _{\boldsymbol b}$ 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 https://hflav.web.cern.ch/. 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
ABAZOV
2006S
 D0 ${{\mathit p}}{{\overline{\mathit p}}}$ at 1.96 TeV
$0.152$ $\pm0.007$ $\pm0.011$ 2
ACOSTA
2004A
 CDF ${{\mathit p}}{{\overline{\mathit p}}}$ at $1.8$ TeV
$0.1312$ $\pm0.0049$ $\pm0.0042$ 3
ABBIENDI
2003P
 OPAL ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$
$0.127$ $\pm0.013$ $\pm0.006$ 4
ABREU
2001L
 DLPH ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$
$0.1192$ $\pm0.0068$ $\pm0.0051$ 5
ACCIARRI
1999D
 L3 ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$
$0.121$ $\pm0.016$ $\pm0.006$ 6
ABREU
1994J
 DLPH ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$
$0.114$ $\pm0.014$ $\pm0.008$ 7
BUSKULIC
1994G
 ALEP ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$
$0.129$ $\pm0.022$ 8
BUSKULIC
1992B
 ALEP ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$
$0.176$ $\pm0.031$ $\pm0.032$ 1112 9
ABE
1991G
 CDF ${{\mathit p}}{{\overline{\mathit p}}}$ $1.8$ TeV
$0.148$ $\pm0.029$ $\pm0.017$ 10
ALBAJAR
1991D
 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
ABE
1997I
 CDF Repl. by ACOSTA 2004A
$0.1107$ $\pm0.0062$ $\pm0.0055$ 12
ALEXANDER
1996
OPAL Rep. by ABBIENDI 2003P
$0.136$ $\pm0.037$ $\pm0.040$ 13
UENO
1996
AMY ${{\mathit e}^{+}}{{\mathit e}^{-}}$ at $57.9$ GeV
$0.144$ $\pm0.014$ ${}^{+0.017}_{-0.011}$ 14
ABREU
1994F
 DLPH Sup. by ABREU 1994J
$0.131$ $\pm0.014$ 15
ABREU
1994J
 DLPH ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$
$0.123$ $\pm0.012$ $\pm0.008$
ACCIARRI
1994D
 L3 Repl. by ACCIARRI 1999D
$0.157$ $\pm0.020$ $\pm0.032$ 16
ALBAJAR
1994
UA1 $\sqrt {\mathit s }$ = 630 GeV
$0.121$ ${}^{+0.044}_{-0.040}$ $\pm0.017$ 1665 17
ABREU
1993C
 DLPH Sup. by ABREU 1994J
$0.143$ ${}^{+0.022}_{-0.021}$ $\pm0.007$ 18
AKERS
1993B
 OPAL Sup. by ALEXANDER 1996
$0.145$ ${}^{+0.041}_{-0.035}$ $\pm0.018$ 19
ACTON
1992C
 OPAL ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$
$0.121$ $\pm0.017$ $\pm0.006$ 20
ADEVA
1992C
 L3 Sup. by ACCIARRI 1994D
$0.132$ $\pm0.22$ ${}^{+0.015}_{-0.012}$ 823 21
DECAMP
1991
ALEP ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$
$0.178$ ${}^{+0.049}_{-0.040}$ $\pm0.020$ 22
ADEVA
1990P
 L3 ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$
$0.17$ ${}^{+0.15}_{-0.08}$ 23, 24
WEIR
1990
MRK2 ${{\mathit e}^{+}}{{\mathit e}^{-}}$ 29 GeV
$0.21$ ${}^{+0.29}_{-0.15}$ 23
BAND
1988
MAC ${\it{}E}^{\it{}ee}_{\rm{}cm}$= 29 GeV
$>0.02 at 90\%\mathit CL$ 23
BAND
1988
MAC ${\it{}E}^{\it{}ee}_{\rm{}cm}$= 29 GeV
$0.121$ $\pm0.047$ 25, 23
ALBAJAR
1987C
 UA1 Repl. by ALBAJAR 1991D
$<0.12 at 90\%\mathit CL$ 26, 23
SCHAAD
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
ADEVA 1992C
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 ${{\mathit Z}^{0}}$
ADEVA 1990P
PL B252 703 A Measurement of ${{\mathit B}^{0}}{{\overline{\mathit B}}^{0}}$ Mixing in ${{\mathit Z}^{0}}$ Decays
WEIR 1990
PL B240 289 A Reanalysis of ${{\mathit B}^{0}}$ $−$ ${{\overline{\mathit B}}^{0}}$ Mixing in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Annihilation at 29 GeV
BAND 1988
PL B200 221 Additional Evidence for ${{\mathit B}^{0}}$ $−$ ${{\overline{\mathit B}}^{0}}$ Mixing
ALBAJAR 1987C
PL B186 247 Search for ${{\mathit B}^{0}}-{{\overline{\mathit B}}^{0}}$ Oscillations at the CERN Proton Antiproton Collider. Paper 2
SCHAAD 1985
PL 160B 188 Upper Limit on ${{\mathit B}^{0}}{{\overline{\mathit B}}^{0}}$ Mixing in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Annihilation at 29 GeV