Measurement of beauty and charm production in pp collisions at $\sqrt{s}$ = 5.02 TeV via non-prompt and prompt D mesons

The collaboration
JHEP 05 (2021) 220, 2021.

Abstract (data abstract)
The $p_{\mathrm{T}}$-differential production cross sections of prompt and non-prompt (produced in beauty-hadron decays) D mesons were measured by the ALICE experiment at midrapidity ($|y|<0.5$) in proton--proton collisions at $\sqrt{s}=5.02~\mathrm{TeV}$. The data sample used in the analysis corresponds to an integrated luminosity of $(19.3\pm0.4)~\mathrm{nb^{-1}}$. D mesons were reconstructed from their decays $\mathrm{D^0 \to K^-\pi^+}$, $\mathrm{D^+\to K^-\pi^+\pi^+}$, and $\mathrm{D_s^+\to \phi\pi^+\to K^-K^+\pi^+}$ and their charge conjugates. Compared to previous measurements in the same rapidity region, the cross sections of prompt $\mathrm{D^+}$ and $\mathrm{D_s^+}$ mesons have an extended $p_{\mathrm{T}}$ coverage and total uncertainties reduced by a factor ranging from 1.05 to 1.6, depending on $p_{\mathrm{T}}$, allowing for a more precise determination of their $p_{\mathrm{T}}$-integrated cross sections. The results are well described by perturbative QCD calculations. The fragmentation fraction of heavy quarks to strange mesons divided by the one to non-strange mesons, $f_\mathrm{s}/(f_\mathrm{u}+f_\mathrm{d})$, is compatible for charm and beauty quarks and with previous measurements at different centre-of-mass energies and collision systems. The $\mathrm{b\overline{b}}$ production cross section per rapidity unit at midrapidity, estimated from non-prompt D-meson measurements, is $\mathrm{d}\sigma_\mathrm{b\overline{b}}/\mathrm{d} y|_\mathrm{|y|<0.5} = 34.5 \pm 2.4 (\mathrm{stat}) ^{+4.7}_{-2.9} (\mathrm{tot.~syst})~\mathrm{\mu b}$. It is compatible with previous measurements at the same centre-of-mass energy and with the cross section predicted by perturbative QCD calculations.