The production cross sections of ${\rm D^0}$ and $\Lambda^+_{\rm c}$ hadrons originating from beauty-hadron decays (i.e. non-prompt) were measured for the first time at midrapidity ($|y|<~0.5$) by the ALICE Collaboration in proton-proton collisions at a center-of-mass energy $\sqrt{s}=13$ TeV. They are described within uncertainties by perturbative QCD calculations employing the fragmentation fractions of beauty quarks to baryons measured at forward rapidity by the LHCb Collaboration. The ${\rm b\overline{b}}$ production cross section per unit of rapidity at midrapidity, estimated from these measurements, is ${\rm d}\sigma_{\rm b\overline{b}}/{\rm d}y|_{|y|<~0.5} = 83.1 \pm 3.5 (\mathrm{stat.}) \pm 5.4(\mathrm{syst.}) ^{+12.3}_{-3.2} (\mathrm{extrap.})\,\mu$b. The baryon-to-meson ratios are computed to investigate the hadronization mechanism of beauty quarks. The non-prompt $\Lambda^+_{\rm c}/{\rm D^0}$ production ratio has a similar trend to the one measured for the promptly produced charmed particles and to the p$/\pi^+$ and $\Lambda/{\rm K^0_S}$ ratios, suggesting a similar baryon-formation mechanism among light, strange, charm, and beauty hadrons. The $p_{\rm T}$-integrated non-prompt $\Lambda_{\rm c}/{\rm D^0}$ ratio is found to be significantly higher than the one measured in e$^+$e$^-$ collisions.
Phys. Rev. D 108, 112003 (2023)
HEP Data
e-Print: arXiv:2308.04873 | PDF | inSPIRE
CERN-EP-2023-159
Figure group
Figure 1
Invariant-mass distributions of the \Dzero- and \Lc-hadron candidates and their charge conjugates produced in pp collisions at $\sqrt{s}=13 \TeV$ and reconstructed at midrapidity, shown in a selected \pt range. The values for the Gaussian mean $\mu$, width $\sigma$, and raw yield $S$ are reported. Top row: \DzerotoKpi meson candidates measured in the $2 < \pt < 4 \GeV/c$ interval. Middle row: \LctopKzeros baryon candidates measured in the $2 < \pt < 4 \GeV/c$ interval. Bottom row: \LctopKpi baryon candidates measured in the $2 < \pt < 4 \GeV/c$ interval. The corresponding BDT probability minimum threshold for the candidate selection is reported. The left (right) column corresponds to the prompt (non-prompt) \Dzero- and \Lc- hadron candidates enriched sample. |    |
Figure 2
Raw-yield distribution as a function of the BDT-based selection employed in the $\chi^{2}$-minimization procedure adopted for the determination of \fnonprompt of \Dzero in $2 < \pt < 4 \GeV/c$ (top left panel), \LctopKpi in $4 < \pt < 6 \GeV/c$ (top right panel), and \LctopKzeros in $6 < \pt < 8 \GeV/c$ (bottom left panel). Bottom right panel: \fnonprompt fraction as function as \pt obtained for the set of selection criteria adopted in the analysis of for non-prompt \Dzero, \LctopKpi, and \LctopKzeros hadrons. |  |
Figure 3
\pt-differential production cross sections of non-prompt \Dzero and \Lc hadrons in pp collisions at ${\s=13 \TeV}$ compared with predictions obtained with \fonll calculations adopting \fbtoB and \fbtoLb fragmentation fractions measured in \ee collisions and LHCb Collaboration (left panel) and the \tamu model (right panel) combined with \pythia for the \HbtoHc decay kinematics. |   |
Figure 4
Beauty production cross section per rapidity unit at midrapidity obtained from from dielectron and non-prompt \Jpsi , \Dzero, and \Lc hadrons measured in pp collisions at $\s=13 \TeV$ compared to FONLL and NNLO predictions. The average $\de\sigma_\bbbar/\de y$ of the estimates from the \Dzero and \Lc hadrons is also reported. |  |
Figure 5
Left: \pt-differential ratios of non-prompt \Lc- and \Dzero-hadron cross sections compared with predictions obtained with \fonll calculations and \pythia for the \HbtoHc decay kinematics. The contributions from beauty mesons and from the \Lb baryon are depicted separately. Right: \pt-differential ratios of prompt and non-prompt \Lc- and \Dzero-hadron cross sections compared with predictions obtained with the \tamu model and \pythia for the \HbtoHc decay kinematics. |   |
Figure 6
Non-prompt $\Lc/\Dzero$, prompt $\Lc/\Dzero$ , $\lmb/\kzero$ , and p$/\pip$ ratios measured in pp collisions at $\s=13 \TeV$ at midrapidity ($|y|<0.5$) compared with the $\Lb/(\Bzero+\Bplus)$ ratio measured by the LHCb Collaboration at forward rapidity ($2.5< y and="" with="" predictions="" obtained="" the="" mc="" generator="" monash="" tune="" modes="" in="" corresponding="" rapidity="" range="" respect="" to="" data.="">< /y> |  |