Charm fragmentation fractions and cc ̄ cross section in p–Pb collisions at sNN=5.02TeV

The total charm-quark production cross section per unit of rapidity dσ(cc¯)/dy, and the fragmentation fractions of charm quarks to different charm-hadron species f(c→hc), are measured for the first time in p–Pb collisions at sNN=5.02TeV 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: D0, D+, Ds+, and J/ψ mesons, and Λc+ and Ξc0 baryons. The resulting cross section is dσ(cc¯)/dy=219.6±6.3(stat.)-11.8+10.5(syst.)-2.9+8.3(extr.)±5.4(BR)±4.6(lumi.)±19.5(rapidity shape)+15.0(Ωc0)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 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 e+e- and e-p collisions. The pT-integrated nuclear modification factor of charm quarks, RpPb(cc¯)=0.91±0.04(stat.)-0.09+0.08(syst.)-0.03+0.05(extr.)±0.03(lumi.), is found to be consistent with unity and with theoretical predictions including nuclear modifications of the parton distribution functions.