${{\mathit \chi}_{{{b}}}}$ 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. We consider here ${{\overline{\mathit \chi}}}$ for hadrons produced in ${{\mathit Z}}$ decays.

VALUE ($ 10^{-2} $) EVTS DOCUMENT ID TECN  COMMENT $\bf{ 12.59 \pm0.42}$ OUR EVALUATION  (from LEP-SLC 2006, eq. 5.39) $\bf{ 12.6 \pm0.4}$ OUR AVERAGE $13.12$ $\pm0.49$ $\pm0.42$ 1 ABBIENDI 2003 P OPAL ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$ $12.7$ $\pm1.3$ $\pm0.6$ 2 ABREU 2001 L DLPH ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$ $11.92$ $\pm0.68$ $\pm0.51$ 3 ACCIARRI 1999 D L3 ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$ $12.1$ $\pm1.6$ $\pm0.6$ 4 ABREU 1994 J DLPH ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$ $11.4$ $\pm1.4$ $\pm0.8$ 5 BUSKULIC 1994 G ALEP ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$ $12.9$ $\pm2.2$ 6 BUSKULIC 1992 B ALEP ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$ • • We do not use the following data for averages, fits, limits, etc. • • $13.2$ $\pm0.1$ $\pm2.4$ 7 ABAZOV 2006 S D0 ${{\mathit p}}{{\overline{\mathit p}}}$ at 1.96 TeV $15.2$ $\pm0.7$ $\pm1.1$ 8 ACOSTA 2004 A CDF ${{\mathit p}}{{\overline{\mathit p}}}$ at $1.8$ TeV $13.1$ $\pm2.0$ $\pm1.6$ 9 ABE 1997 I CDF Repl. by ACOSTA 2004A $11.07$ $\pm0.62$ $\pm0.55$ 10 ALEXANDER 1996 OPAL Rep. by ABBIENDI 2003P $13.6$ $\pm3.7$ $\pm4.0$ 11 UENO 1996 AMY ${{\mathit e}^{+}}{{\mathit e}^{-}}$ at $57.9$ GeV $14.4$ $\pm1.4$ ${}^{+1.7}_{-1.1}$ 12 ABREU 1994 F DLPH Sup. by ABREU 1994J $13.1$ $\pm1.4$ 13 ABREU 1994 J DLPH ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$ $12.3$ $\pm1.2$ $\pm0.8$ ACCIARRI 1994 D L3 Repl. by ACCIARRI 1999D $15.7$ $\pm2.0$ $\pm3.2$ 14 ALBAJAR 1994 UA1 $\sqrt {\mathit s }$ = 630 GeV $12.1$ ${}^{+4.4}_{-4.0}$ $\pm1.7$ 1665 15 ABREU 1993 C DLPH Sup. by ABREU 1994J $14.3$ ${}^{+2.2}_{-2.1}$ $\pm0.7$ 16 AKERS 1993 B OPAL Sup. by ALEXANDER 1996 $14.5$ ${}^{+4.1}_{-3.5}$ $\pm1.8$ 17 ACTON 1992 C OPAL ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$ $12.1$ $\pm1.7$ $\pm0.6$ 18 ADEVA 1992 C L3 Sup. by ACCIARRI 1994D $17.6$ $\pm3.1$ $\pm3.2$ 1112 19 ABE 1991 G CDF ${{\mathit p}}{{\overline{\mathit p}}}$ $1.8$ TeV $14.8$ $\pm2.9$ $\pm1.7$ 20 ALBAJAR 1991 D UA1 ${{\mathit p}}{{\overline{\mathit p}}}$ 630 GeV $13.2$ $\pm22$ ${}^{+1.5}_{-1.2}$ 823 21 DECAMP 1991 ALEP ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$ $17.8$ ${}^{+4.9}_{-4.0}$ $\pm2.0$ 22 ADEVA 1990 P L3 ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}$ $17$ ${}^{+15}_{-8}$ 23, 24 WEIR 1990 MRK2 ${{\mathit e}^{+}}{{\mathit e}^{-}}$ 29 GeV $21$ ${}^{+29}_{-15}$ 23 BAND 1988 MAC ${\it{}E}^{\it{}ee}_{\rm{}cm}$= 29 GeV $>2 at 90\%\mathit CL$ 23 BAND 1988 MAC ${\it{}E}^{\it{}ee}_{\rm{}cm}$= 29 GeV $12.1$ $\pm4.7$ 25, 23 ALBAJAR 1987 C UA1 Repl. by ALBAJAR 1991D $<12 at 90\%\mathit CL$ 26, 23 SCHAAD 1985 MRK2 ${\it{}E}^{\it{}ee}_{\rm{}cm}$= 29 GeV 1  The average ${{\mathit B}}$ mixing parameter is determined simultaneously with ${{\mathit b}}$ and ${{\mathit c}}$ forward-backward asymmetries in the fit. 2  The experimental systematic and model uncertainties are combined in quadrature. 3  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. 4  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. 5  BUSKULIC 1994G data analyzed using ${{\mathit e}}{{\mathit e}}$, ${{\mathit e}}{{\mathit \mu}}$, and ${{\mathit \mu}}{{\mathit \mu}}$ events. 6  BUSKULIC 1992B uses a jet charge technique combined with electrons and muons. 7  Uses the dimuon charge asymmetry. Averaged over the mix of ${{\mathit b}}$-flavored hadrons. 8  Measurement performed using events containing a dimuon or an ${{\mathit e}}/{{\mathit \mu}}$ pair. 9  Uses di-muon events. 10  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 ${{\mathit c}}{{\overline{\mathit c}}}$. 11  UENO 1996 extracted $\chi $ from the energy dependence of the forward-backward asymmetry. 12  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 ${{\overline{\mathit \chi}}}$ = ${{\mathit f}_{{{d}}}}{{\mathit \chi}_{{{d}}}}+0.9{{\mathit f}_{{{s}}}}{{\mathit \chi}_{{{s}}}}$. 13  This ABREU 1994J result combines ${{\mathit \ell}}{{\mathit \ell}}$, ${{\mathit \Lambda}}{{\mathit \ell}}$, and jet-charge ${{\mathit \ell}}$ (ABREU 1994F) analyses. It is for ${{\overline{\mathit \chi}}}$ = $\mathit f_{\mathit d}{{\mathit \chi}_{{{d}}}}+0.96\mathit f_{\mathit s}{{\mathit \chi}_{{{s}}}}$. 14  ALBAJAR 1994 uses dimuon events. Not independent of ALBAJAR 1991D. 15  ABREU 1993C data analyzed using ${{\mathit e}}{{\mathit e}}$, ${{\mathit e}}{{\mathit \mu}}$, and ${{\mathit \mu}}{{\mathit \mu}}$ events. 16  AKERS 1993B analysis performed using dilepton events. 17  ACTON 1992C uses electrons and muons. Superseded by AKERS 1993B. 18  ADEVA 1992C uses electrons and muons. 19  ABE 1991G measurement of $\chi $ is done with ${{\mathit e}}{{\mathit \mu}}$ and ${{\mathit e}}{{\mathit e}}$ events. 20  ALBAJAR 1991D measurement of $\chi $ is done with dimuons. 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