The production of $B^{ \pm}$ mesons is studied in $pp$ collisions at centre-of-mass energies of 7 and 13 TeV, using $B^{ \pm}\rightarrow J/\psi K^{ \pm}$ decays and data samples corresponding to 1.0 fb$^{ -1}$ and 0.3 fb$^{ -1}$, respectively. The production cross-sections summed over both charges and integrated over the transverse momentum range $0<p_{ \text{ T}}< 40$ GeV/$c$ and the rapidity range $2.0<y<4.5$ are measured to be $\sigma(pp \rightarrow B^{ \pm} X, \sqrt{ s} = \text{ 7 TeV}) = 43.0 \pm 0.2 \pm 2.5 \pm 1.7\mu b,$ $\sigma(pp \rightarrow B^{ \pm} X, \sqrt{ s} = \text{ 13 TeV}) = 86.6 \pm 0.5 \pm 5.4 \pm 3.4\mu b,$ where the first uncertainties are statistical, the second are systematic, and the third are due to the limited knowledge of the $B^{ \pm}\rightarrow J/\psi K^{ \pm}$ branching fraction. The ratio of the cross-section at 13 TeV to that at 7 TeV is determined to be $2.02\pm0.02\text{ (stat)}\pm0.12\text{ (syst)}$. Differential cross-sections are also reported as functions of $p_{ \text{ T}}$ and $y$. All results are in agreement with theoretical calculations based on the state-of-art fixed next-to-leading order quantum chromodynamics.
Categories: hep-ex