Measurement of the relative $B^{\pm}_{c}/B^{\pm}$ production cross section with the ATLAS detector at $\sqrt{s}=8$ TeV

Abstract

The total cross section and differential cross sections for the production of $B_{c}^{\pm}$ mesons, times their branching fraction to $J/\psi \pi^{\pm}$, are measured relative to those for the production of $B^{\pm}$ mesons, times their branching fraction to $J/\psi K^{\pm}$. The data used for this study correspond to an integrated luminosity of $20.3\,\mathrm{fb}^{-1}$ of $pp$ collisions recorded by the ATLAS detector at the Large Hadron Collider in 2012 at a center-of-mass energy of $\sqrt{s} = 8$ TeV. The measurement is performed differentially in bins of transverse momentum $p_{\mathrm{T}}$ for $13$ GeV $<p_{\mathrm{T}}(B_{c}^{\pm})<22$ GeV and $p_{\mathrm{T}}(B_{c}^{\pm}) > 22$ GeV and in bins of rapidity $y$ for $|y| <0.75$ and $0.75<|y|<2.3$. The relative cross section times branching fraction for the full range $p_{\mathrm T} > 13$ GeV and $|y| < 2.3$ is $(0.34\,\pm\,0.04_{\text{stat}}\,^{+0.06}_{-0.02}\,_{\text{sys}}\,\pm\,0.01_{\text{lifetime}})\%$. The differential measurements suggest that the production cross section of the $B^{\pm}_c$ decreases faster with $p_{\mathrm T}$ than the production cross section of the $B^{\pm}$, while no significant dependence on rapidity is observed.