Experiment	Measurement	Reference
LHCb	\([0.34 \pm 0.04\mbox{ (stat)} \pm 0.03\mbox{ (syst)} \pm 0.01\mbox{ (R(psi))}]\)	Nucl.Phys. B 871 (2013) 403-419
Average	\(\mathbf{[0.34 \pm 0.05\mbox{ (combined)}]}\)