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

ExperimentMeasurement [10-9]$\Delta\chi^2$ReferenceComments
Average$< 2.5$
PDG$< 2.5$pdgLive
LHCb$< 2.5$Phys.Rev.Lett. 124,211802 (2020)
CDF$< 83$Phys.Rev.Lett. 102,201801 (2009)
BaBar$< 113$Phys.Rev.D 77,032007 (2008)
Belle$< 190$Phys.Rev.D 68,111101 (2003)
Quoted upper limits are at 90% confidence level (CL), unless mentioned otherwise.