Experiment	Measurement	Reference
LHCb	< \(1.5 \times 10^{-6}\)	Phys. Rev. D 92, 112002 (2015)
BaBar	< \(0.016 \times 10^{-4}\)	PRD 70 091104 (2004)
Average	< \(\mathbf{1.5 \times 10^{-6}}\)