Charm fragmentation fractions and $\mathrm{c}\overline{\mathrm{c}}$ cross section in p$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV

Abstract

The total charm-quark production cross section per unit of rapidity $\mathrm{d}\sigma (\mathrm{c}\overline{\mathrm{c}})/\mathrm{d}y$, and the fragmentation fractions of charm quarks to different charm-hadron species $f(\mathrm{c}\to {\mathrm{h}}_{\mathrm{c}})$, are measured for the first time in p$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV at midrapidity ($-0.96<y<0.04$ in the centre-of-mass frame) using data collected by ALICE at the CERN LHC. The results are obtained based on all the available measurements of prompt production of ground-state charm-hadron species: ${\mathrm{D}}^0$, ${\mathrm{D}}^{+}$, ${\mathrm{D}}_{\mathrm{s}}^{+}$, and $J/\psi$ mesons, and ${\Lambda }_{\mathrm{c}}^{+}$ and ${\Xi }_{\mathrm{c}}^0$ baryons. The resulting cross section is $\mathrm{d}\sigma (\mathrm{c}\overline{\mathrm{c}})/\mathrm{d}y=219.6\pm 6.3(stat.){}_{-11.8}^{+10.5}(syst.){}_{-2.9}^{+8.3}(extr.)\pm 5.4(\mathrm{BR})\pm 4.6(lumi.)\pm 19.5(\text{rapidity shape})+15.0({\Omega }_{\mathrm{c}}^0)$ mb, which is consistent with a binary scaling of pQCD calculations from pp collisions. The measured fragmentation fractions are compatible with those measured in pp collisions at $\sqrt{s}=5.02$ and $13$ TeV, showing an increase in the relative production rates of charm baryons with respect to charm mesons in pp and p$-$Pb collisions compared with ${\mathrm{e}}^{+}{\mathrm{e}}^{-}$ and ${\mathrm{e}}^{-}\mathrm{p}$ collisions. The $p_{\mathrm{T}}$-integrated nuclear modification factor of charm quarks, $R_{\mathrm{pPb}}(\mathrm{c}\overline{\mathrm{c}})=0.91\pm 0.04(stat.){}_{-0.09}^{+0.08}(syst.){}_{-0.03}^{+0.05}(extr.)\pm 0.03(lumi.)$, is found to be consistent with unity and with theoretical predictions including nuclear modifications of the parton distribution functions.

21 pages, 2 captioned figures, 2 tables, authors from page 15, published version, figures at http://alice-publications.web.cern.ch/node/10966

References in corpus (17)

• PYTHIA 6.4 Physics and Manual
• Implications of CTEQ global analysis for collider observables
• Measurement of visible cross sections in proton-lead collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV in van der Meer scans with the ALICE detector
• Triple parton scatterings in high-energy proton-proton collisions
• Nuclear PDFs After the First Decade of LHC Data
• Observation of a multiplicity dependence in the $p_{\mathrm{T}}$-differential charm baryon-to-meson ratios in proton-proton collisions at $\sqrt{s}=13$ TeV
• Measurement of $B^{+}$, $B^0$ and ${\Lambda }_b^0$ production in $p\mathrm{Pb}$ collisions at $\sqrt{s_{\mathrm{NN}}}=8.16\mathrm{TeV}$
• Charm production and fragmentation fractions at midrapidity in pp collisions at $\sqrt{s}=13$ TeV
• First measurement of ${\Lambda }_{\mathrm{c}}^{+}$ production down to $p_{\mathrm{T}}=0$ in pp and p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV
• Enhanced production of ${\Lambda }_b^0$ baryons in high-multiplicity $pp$ collisions at $\sqrt{s}=13$ TeV
• Measurements of inclusive J/$\psi$ production at midrapidity and forward rapidity in Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV
• $\psi (2S)$ suppression in Pb-Pb collisions at the LHC
• Study of flavor dependence of the baryon-to-meson ratio in proton-proton collisions at $\sqrt{s}=13$ TeV
• Production of light flavor and single-charmed hadrons in $pp$ collisions at $\sqrt{s}=5.02$ TeV in an equal-velocity quark combination model
• Measurement of the ${\Lambda }_c^{+}$ to $D^0$ production cross-section ratio in peripheral PbPb collisions
• Measurement of ${\Xi }_c^{+}$ production in $p$Pb collisions at $\sqrt{s_{NN}}=8.16$ TeV at LHCb
• Inclusive, prompt and non-prompt $\mathrm{J}/\psi$ production at midrapidity in p$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV