The prompt production of the charm baryon Lambda(c+) and the A(c)(+)/D-0 production ratios were measured at midrapidity with the ALICE detector in pp and (p)-Pb collisions at root S-NN = 5.02 TeV. These new measurements show a clear decrease of the Lambda(+)(c)/D-0 ratio with increasing transverse momentum (p(T)) in both collision systems in the range 2 < P-T < 12 GeV/c, exhibiting similarities with the light-flavor baryon-tomeson ratios p/pi and Lambda/K-S(0). At low p(T), predictions that include additional color-reconnection mechanisms beyond the leading-color approximation, assume the existence of additional higher-mass charm-baryon states, or include hadronization via coalescence can describe the data, while predictions driven by charmquark fragmentation processes measured in e(+) e(-) and e(-) p collisions significantly underestimate the data. The results presented in this Letter provide significant evidence that the established assumption of universality (colliding-system independence) of parton-to-hadron fragmentation is not sufficient to describe charm-baryon production in hadronic collisions at LHC energies.

Λ_{c}^{+} Production and Baryon-to-Meson Ratios in pp and p-Pb Collisions at √s_{NN}=5.02  TeV at the LHC

Buckland, M D;Camerini, P;Contin, G;De Martin, C;Fragiacomo, E;Luparello, G;Margagliotti, G V;Piano, S;Rui, R;Zaccolo, V;
2021

Abstract

The prompt production of the charm baryon Lambda(c+) and the A(c)(+)/D-0 production ratios were measured at midrapidity with the ALICE detector in pp and (p)-Pb collisions at root S-NN = 5.02 TeV. These new measurements show a clear decrease of the Lambda(+)(c)/D-0 ratio with increasing transverse momentum (p(T)) in both collision systems in the range 2 < P-T < 12 GeV/c, exhibiting similarities with the light-flavor baryon-tomeson ratios p/pi and Lambda/K-S(0). At low p(T), predictions that include additional color-reconnection mechanisms beyond the leading-color approximation, assume the existence of additional higher-mass charm-baryon states, or include hadronization via coalescence can describe the data, while predictions driven by charmquark fragmentation processes measured in e(+) e(-) and e(-) p collisions significantly underestimate the data. The results presented in this Letter provide significant evidence that the established assumption of universality (colliding-system independence) of parton-to-hadron fragmentation is not sufficient to describe charm-baryon production in hadronic collisions at LHC energies.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11368/3028024
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