| Experiment | Measurement | Reference |
|---|---|---|
| Belle | \([1.39 \pm 0.18\mbox{ (stat)} \pm 0.26\mbox{ (syst)}] \times 10^{-4}\) | PRD 74, 092002 (2006) |
| BaBar | \([3.05 \pm 0.14\mbox{ (stat)} \pm 0.28\mbox{ (syst)}] \times 10^{-4}\) | PRD 84, 112007 (2011) |
| Average | \(\mathbf{[2.23 \pm 0.22\mbox{ (combined)}] \times 10^{-4}}\) |