Measurement of the $B^{\pm}$ production cross-section in pp collisions at $\sqrt{s} =$ 7 and 13 TeV

The production of B$^{±}$ mesons is studied in pp collisions at centre-of-mass energies of 7 and 13 TeV, using B$^{±}$ → J/ψ K$^{±}$ 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$_{T}$ < 40 GeV/c and the rapidity range 2.0 < y < 4.5 are measured to be $ \begin{array}{l}\sigma \left( pp\to {B}^{\pm }X,\sqrt{s}=7\kern0.5em \mathrm{T}\mathrm{e}\mathrm{V}\right)=43.0\pm 0.2\pm 2.5\pm 1.7\kern0.5em \upmu \mathrm{b},\hfill \\ {}\sigma \left( pp\to {B}^{\pm }X,\sqrt{s}=13\kern0.5em \mathrm{T}\mathrm{e}\mathrm{V}\right)=86.6\pm 0.5\pm 5.4\pm 3.4\kern0.5em \upmu \mathrm{b},\hfill \end{array} $ where the first uncertainties are statistical, the second are systematic, and the third are due to the limited knowledge of the B$^{±}$ → J/ψ K$^{±}$ branching fraction. The ratio of the cross-section at 13 TeV to that at 7 TeV is determined to be 2.02 ± 0.02 (stat) ± 0.12 (syst). Differential cross-sections are also reported as functions of p$_{T}$ and y. All results are in agreement with theoretical calculations based on the state-of-art fixed next-to-leading order quantum chromodynamics.