PRL 108, 251802 (2012)

LHCb: INSPIRE

ParameterMeasurement
\(\frac{{\cal{B}} ( B_c^- \to J/\psi \pi^+ \pi^- \pi^- )} {{\cal{B}} ( B_c^- \to J/\psi \pi^- )}\)\([2.41 \pm 0.30\mbox{ (stat)} \pm 0.33\mbox{ (syst)}]\)