Recent pT-integrated cross-section measurements of the ground-state charm mesons and baryons, D0, Dþ, Dþs , Λþc , and Ξ0c, are used to evaluate the charm fragmentation fractions and production cross section pffiffi per unit of rapidity at midrapidity (jyj < 0.5), in pp collisions at s 1⁄4 5.02 TeV at the LHC. The latter is dσcc ̄=dyj 1⁄4 1165 44ðstatÞþ134ðsystÞ μb. These measurements were obtained for the first time in jyj<0.5 −101 hadronic collisions at the LHC, including the charm baryon states, recently measured by ALICE at midrapidity. The charm fragmentation fractions differ significantly from the values measured in eþe− and ep collisions, providing evidence of the dependence of the parton-to-hadron fragmentation fractions on the collision system, indicating that the assumption of their universality is not supported by the measured cross sections. An increase of a factor of about 3.3 for the fragmentation fraction for the Λþc with a significance of 5σ between the values obtained in pp collisions and those obtained in eþe− (ep) collisions is reported. The fragmentation fraction for the Ξ0c was obtained for the first time in any collision system. The measured fragmentation fractions were used to update the cc ̄ cross sections per unit of rapidity at jyj < 0.5 at pffiffi s 1⁄4 2.76 and 7 TeV, which are about 40% higher than the previously published results. The data were compared with perturbative-QCD calculations and lie at the upper edge of the theoretical bands.

Charm-quark fragmentation fractions and production cross section at midrapidity in pp collisions at the LHC

P. Camerini;G. Contin;C. De Martin;M. Faggin;E. Fragiacomo;G. Luparello;G. ???V. Margagliotti;S. Piano;A. Rosano;R. Rui;V. Zaccolo;
2022-01-01

Abstract

Recent pT-integrated cross-section measurements of the ground-state charm mesons and baryons, D0, Dþ, Dþs , Λþc , and Ξ0c, are used to evaluate the charm fragmentation fractions and production cross section pffiffi per unit of rapidity at midrapidity (jyj < 0.5), in pp collisions at s 1⁄4 5.02 TeV at the LHC. The latter is dσcc ̄=dyj 1⁄4 1165 44ðstatÞþ134ðsystÞ μb. These measurements were obtained for the first time in jyj<0.5 −101 hadronic collisions at the LHC, including the charm baryon states, recently measured by ALICE at midrapidity. The charm fragmentation fractions differ significantly from the values measured in eþe− and ep collisions, providing evidence of the dependence of the parton-to-hadron fragmentation fractions on the collision system, indicating that the assumption of their universality is not supported by the measured cross sections. An increase of a factor of about 3.3 for the fragmentation fraction for the Λþc with a significance of 5σ between the values obtained in pp collisions and those obtained in eþe− (ep) collisions is reported. The fragmentation fraction for the Ξ0c was obtained for the first time in any collision system. The measured fragmentation fractions were used to update the cc ̄ cross sections per unit of rapidity at jyj < 0.5 at pffiffi s 1⁄4 2.76 and 7 TeV, which are about 40% higher than the previously published results. The data were compared with perturbative-QCD calculations and lie at the upper edge of the theoretical bands.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11368/3038502
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