JHEP 1311 (2013) 094

LHCb: INSPIRE

ParameterMeasurement
\(\frac{{\cal{B}} ( B_c^- \to J/\psi K^- K^+ \pi^- )} { {\cal{B}} ( B_c^- \to J/\psi \pi^- )}\)\([0.53 \pm 0.10\mbox{ (stat)} \pm 0.05\mbox{ (syst)}]\)