Ac+ Production and Baryon-to-Meson Ratios in pp and p-Pb Collisions at √SNN=5.02 TeV at the LHC

Acharya, S.; Adamova, D.; Adler, A.; Adolfsson, J.; Rinella, G. Aglieri; Agnello, M.; Agrawal, N.; Ahammed, Z.; Ahmad, S.; Ahn, S. U.; Akbar, Z.; Akindinov, A.; Al-Turany, M.; Albuquerque, D. S. D.; Aleksandrov, D.; Alessandro, B.; Alfanda, H. M.; Alfaro Molina, R.; Ali, B.; Ali, Y.; Alici, A.; Alizadehvandchali, N.; Alkin, A.; Alme, J.; Alt, T.; Altenkamper, L.; Altsybeev, I.; Anaam, M. N.; Andrei, C.; Andreou, D.; Andronic, A.; Angeletti, M.; Anguelov, V.; Anticic, T.; Antinori, F.

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摘要

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.

关键词

MULTIPLICITY DEPENDENCE RAPIDITY PROTON KAON PION