/ hep-ex CMS-BPH-12-011

Measurement of the ratio $\mathcal{B}( \mathrm{B_c^+} \rightarrow \mathrm{J}/\psi\, \pi^+ \pi^+ \pi^-)/\mathcal{B}( \mathrm{B_c^+} \rightarrow \mathrm{J}/\psi\, \pi^+)$ and the production cross sections times branching fractions of $\mathrm{ B_c^+} \rightarrow \mathrm{J}/\psi\, \pi^+$ and $\mathrm{ B^+} \rightarrow \mathrm{J}/\psi\, \mathrm{K}^+$ in pp collisions at $\sqrt{s}$ = 7 TeV

Pages: 29

Abstract: The $\mathrm{B_c^+} \rightarrow \mathrm{J}/\psi\, \pi^+$ and $\mathrm{B_c^+} \rightarrow \mathrm{J}/\psi\, \pi^+ \pi^+ \pi^-$ decay modes are studied in proton-proton collisions at a center-of-mass energy of $7~\mathrm{TeV}$ with the CMS detector at the LHC. The kinematic region investigated requires $\mathrm{B_c^+}$ mesons with transverse momentum $p_{\mathrm{T}}$ greater than $15~\mathrm{GeV}$ and rapidity $|y|$ lower than $1.6$. The data sample corresponds to an integrated luminosity of $5.1~\mathrm{fb}^{-1}$. The ratio of the branching fractions $\mathcal{B}( \mathrm{B_c^+} \rightarrow \mathrm{J}/\psi\, \pi^+ \pi^+ \pi^-)/\mathcal{B}( \mathrm{B_c^+} \rightarrow \mathrm{J}/\psi\, \pi^+)$ is measured to be $2.55 \pm 0.80~\mathrm{(stat)} \pm 0.33~\mathrm{(syst)}~^{+ 0.04}_{-0.01}~(\tau_{\mathrm{B_c^+}})$. The ratio of the production cross sections times branching fractions $(~\sigma( \mathrm{B_c^+} )~\mathcal{B} ( \mathrm{B_c^+} \rightarrow \mathrm{J}/\psi\, \pi^+ )~)/(~\sigma( \mathrm{B^+} )~\mathcal{B} ( \mathrm{B^+} \rightarrow \mathrm{J}/\psi\, \mathrm{K}^+ )~)$ is determined to be $[0.48 \pm 0.05~\mathrm{(stat)} \pm 0.03~\mathrm{(syst)} \pm 0.05~(\tau_{\mathrm{B_c^+}})]\%$.

Note: Submitted to JHEP

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