Studying charm hadronization … Λ c /D in pp Charm baryon-to-meson ratio in pp : factor ~3 larger ( p T <5 GeV/ c ) than what expected from e + e - collisions: Challenge for universality of the fragmentation functions? -> z-value measurement needed to conclude a.grelli Nikhef Stafoverleg 17/10/2019
Studying charm hadronization … Λ c /D in pp, Pb-Pb Charm baryon-to-meson ratio in pp : factor ~3 larger ( p T <5 GeV/ c ) than what 1.2 0 / D expected from e + e - collisions: 0 10% Pb Pb − − ALICE Preliminary + c 30 50% Pb Pb − − Challenge for universality of the fragmentation functions? -> z-value measurement Λ s = 5.02 TeV, | y | < 0.5 1 NN pp needed to conclude 0.8 Charm baryon-to-meson ratio in Pb-Pb : Similar results as in pp but slightly larger 0.6 0.4 0.2 Filled markers: pp measured reference Open markers: pp p -extrapolated reference T 0 1 10 p (GeV/ c ) T ALI − PREL − 323761 a.grelli Nikhef Stafoverleg 17/10/2019
Studying charm hadronization … Λ c /D in Pb-Pb Charm baryon-to-meson ratio in pp : factor ~3 larger ( p T <5 GeV/ c ) than what expected from e + e - collisions: Challenge for universality of the fragmentation functions? -> z-value measurement needed to conclude Charm baryon-to-meson ratio in Pb-Pb : Similar results as in pp but slightly larger Charm baryon-to-meson ratio in Pb-Pb : Does hadronization via recombination play a role? or “just” fragmentation? -> need more precision to conclude (stat. and syst) a.grelli Nikhef Stafoverleg 17/10/2019
Studying charm hadronization … ALICE upgrade: new tracker Charm baryon-to-meson ratio in pp : factor ~3 larger ( p T <5 GeV/ c ) than what expected from e + e - collisions: Challenge for universality of the fragmentation functions? -> z-value measurement needed to conclude Charm baryon-to-meson ratio in Pb-Pb : Similar results as in pp but slightly larger Charm baryon-to-meson ratio in Pb-Pb : Does hadronization via recombination play a role? or “just” fragmentation? -> need more precision to conclude (stat. and syst) ALICE upgrade : Future is coming fast and soon we will be able to collect and analyse LHC run III data -> Nikhef among the main players on ALICE tracker upgrade Factor 3 improvement in r- 𝜒 resolution: ~ 20 μ m at 1 GeV/c in Pb-Pb! a.grelli Nikhef Stafoverleg 17/10/2019
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