Experiment
Measurement
Reference
LHCb
< \(5.2 \times 10^{-7}\)
JHEP 09 (2013) 006
Belle
< \(8.3 \times 10^{-7}\)
PRD 72, 051105(R) (2005)
BaBar
< \(1.9 \times 10^{-6}\)
PRL 90 231801 (2003)
Average
< \(\mathbf{5.2 \times 10^{-7}}\)
