${\cal B}(B_s^0 \to \pi^+ \pi^-)$

ExperimentMeasurement [10-7]$\Delta\chi^2$ReferenceComments
Average$7.2\,^{+1.1}_{-1.0}$9.75$p=0.94$ (ndf=18)
PDG$7.0 \pm1.0$pdgLive
Belle$< 120$Phys.Rev.D 82,072007 (2010)
CDF$( {\cal B}(B_s^0 \to \pi^+ \pi^-) / {\cal B}(B^0 \to K^+ \pi^-) ) \frac{f_s}{f_d}$0.17 Phys.Rev.Lett. 108,211803 (2012)
LHCb$( {\cal B}(B_s^0 \to \pi^+ \pi^-) / {\cal B}(B^0 \to K^+ \pi^-) ) \frac{f_s}{f_d}$0.04 Phys.Rev.Lett. 118,081801 (2017)
Quoted upper limits are at 90% confidence level (CL), unless mentioned otherwise.

Further parameters used in the fit and their correlation with the average

SourceParameterCorrelation [%]Value$\Delta\chi^2$
fit${\cal B}(B_s^0 \to K^+ K^-)$58.9$2.66\,^{+0.32}_{-0.27} \times 10^{-5}$
fit${\cal B}(B_s^0 \to K^- \pi^+)$47.8$5.90\,^{+0.87}_{-0.76} \times 10^{-6}$
fit${\cal B}(B^0 \to K^+ \pi^-)$15.5$1.946 \pm0.046 \times 10^{-5}$
fit${\cal B}(B^0 \to \pi^+ \pi^-)$3.9$5.15 \pm0.19 \times 10^{-6}$
fit${\cal B}(B^0 \to K^+ K^-)$1.9$8.0 \pm1.5 \times 10^{-8}$
fit${\cal B}(\Lambda_b^0 \to p \pi^-)$1.2$4.55\,^{+0.91}_{-0.82} \times 10^{-6}$
fit${\cal B}(\Lambda_b^0 \to p K^-)$1.0$5.4 \pm1.1 \times 10^{-6}$
fit${\cal B}(\Lambda_b^0 \to \Lambda^0 \phi(1020))$-0.2$1.01\,^{+0.29}_{-0.25} \times 10^{-5}$
fit${\cal B}(B^0 \to \phi(1020) K^0)$-0.0$7.25 \pm0.60 \times 10^{-6}$
fit${\cal B}(B_s^0 \to K^0 \bar{K}^0)$-0.0$1.74 \pm0.31 \times 10^{-5}$
external$\frac{f_s}{f_d}$-64.7$0.241 \pm0.023$0.05
external$f_{\Lambda^0_b}$0.4$8.1 \pm1.1 \times 10^{-2}$0.09
external$f_{d}$-0.0$0.4083 \pm0.0070$0.00
Parameters of interest whose average is determined from individual measurements are called fit parameters. Parameters that are needed by the fit (in particular daughter branching fraction) and whose average is not determined here, but taken from somewhere else (usually PDG) are called external parameters.