# Measurements of $B_c^+$ production and mass with the $B_c^+ \to J/\psi \pi^+$ decay

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## Abstract

Measurements of $B_c^+$ production and mass are performed with the decay mode $B_c^+ \to J/\psi \pi^+$ using 0.37 fb$^{-1}$ of data collected in $pp$ collisions at $\sqrt{s}=7$ TeV by the LHCb experiment. The ratio of the production cross-section times branching fraction between the $B_c^+ \to J/\psi \pi^+$ and the $B^+ \to J/\psi K^+$ decays is measured to be $(0.68 \pm 0.10\,({\rm stat.}) \pm 0.03\,({\rm syst.}) \pm 0.05\,({\rm lifetime}))$% for $B_c^+$ and $B^+$ mesons with transverse momenta $p_{\rm T}>4$GeV/$c$ and pseudorapidities $2.5<\eta<4.5$. The $B_c^+$ mass is directly measured to be $6273.7 \pm 1.3\,({\rm stat.}) \pm 1.6 \,({\rm syst.})$ MeV/$c^2$, and the measured mass difference with respect to the $B^+$ meson is $M(B_c^+)-M(B^+) = 994.6 \pm 1.3\,({\rm stat.}) \pm 0.6\,({\rm syst.})$ MeV/$c^2$.

## Figures and captions

 Invariant mass distributions of selected (a) $B_c^+\rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \pi^+$ candidates and (b) $B^+\rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} K^+$ candidates, used in the production measurement. The fits to the data are superimposed. Fig1a.pdf [18 KiB] HiDef png [264 KiB] Thumbnail [93 KiB] *.C file Fig1b.pdf [24 KiB] HiDef png [225 KiB] Thumbnail [79 KiB] *.C file Invariant mass distribution of $B_c^+\rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \pi^+$ decays, used in the mass measurement. The fit to the data is superimposed. Fig2.pdf [18 KiB] HiDef png [271 KiB] Thumbnail [92 KiB] *.C file Animated gif made out of all figures. PAPER-2012-028.gif Thumbnail

## Tables and captions

 Systematic uncertainties (in ${\mathrm{\,MeV\!/}c^2}$) of the $B_c^+$ mass and mass difference $\Delta M = M( B _ c ^+ )-M( B ^+ )$. Table_1.pdf [40 KiB] HiDef png [113 KiB] Thumbnail [16 KiB] tex code

Created on 09 December 2018.Citation count from INSPIRE on 18 December 2018.