Measurement of the ratio of the production cross-section times branching fraction between the Bc to J/psi pi and the B+ to J/psi K and of branching fractions Bc to J/psi pi pi pi over Bc to J/psi pi in CMS at sqrt(s)=7 TeV.

The $\mathrm{B^{\pm}_c} \to J/\psi \pi^{\pm}$ and $\mathrm{B^{\pm}_c} \to J/\psi \pi^{\pm} \pi^{\pm} \pi^{\mp} $ decay modes are studied in CMS in the kinematic region where the transverse momentum of the $\mathrm{B^{\pm}_c}$ meson is greater than 15 GeV/c and within the central rapidity region $|y|<$ 1.6. Two ratios are measured: $\frac{\sigma(\mathrm{B^{\pm}_c})\times \mathrm{Br}(\mathrm{B^{\pm}_c} \to J/\psi \pi^{\pm})} {\sigma(\mathrm{B^{\pm}})\times \mathrm{Br}(\mathrm{B^{\pm}} \to J/\psi \mathrm{K^{\pm}})}= (0.48 \pm 0.05 \,(stat) \pm 0.04 \,(syst) \,{^{+0.05}_{-0.03}}\, (\tau_{Bc})) \times 10^{-2}$ and $\frac{\mathrm{Br}(\mathrm{B^{\pm}_c} \to J/\psi \pi^{\pm}\pi^{\pm}\pi^{\mp})}{\mathrm{Br}(\mathrm{B_c^{\pm}} \to J/\psi \pi^{\pm})}= 2.43\pm0.76 \,(stat) \,{^{+0.46}_{-0.44}} \,(syst).$