Abstract
The p_{T}-differential production cross sections of prompt D^{0}, Λ_{c}^{+}, and Σ_{c}^{0,++}(2455) charmed hadrons are measured at midrapidity (|y|<0.5) in pp collisions at sqrt[s]=13 TeV. This is the first measurement of Σ_{c}^{0,++} production in hadronic collisions. Assuming the same production yield for the three Σ_{c}^{0,+,++} isospin states, the baryon-to-meson cross section ratios Σ_{c}^{0,+,++}/D^{0} and Λ_{c}^{+}/D^{0} are calculated in the transverse momentum (p_{T}) intervals 2<p_{T}<12 and 1<p_{T}<24 GeV/c. Values significantly larger than in e^{+}e^{-} collisions are observed, indicating for the first time that baryon enhancement in hadronic collisions also extends to the Σ_{c}. The feed-down contribution to Λ_{c}^{+} production from Σ_{c}^{0,+,++} is also reported and is found to be larger than in e^{+}e^{-} collisions. The data are compared with predictions from event generators and other phenomenological models, providing a sensitive test of the different charm-hadronization mechanisms implemented in the models.
Highlights
The formation of hadrons out of quarks (“hadronization”) represents a fundamental process in nature that can be investigated at particle colliders where, at high collision energies, quarks represent the relevant degrees of freedom for a very short time on the order of 10−23 s
Recent measurements of Λpþcffiffi, Ξ0c, and Λ0b-baryon production in pp collisions at s 1⁄4 5.02, 7, and 13 TeV [1,2,3,4,5,6,7,8] indicate that the production of charm and beauty baryons relative to that of charm and beauty mesons is enhanced in pp with respect to eþe− and ep collisions [9,10,11,12,13,14,15]
In eþe− collisions, while in the light-flavor sector the mass dependence of the yields of the Σ and Λ states is well described by a single exponential function, the yields of the Σ0c;þ;þþ states are about a factor 4 smaller than those of the Λþc states [24]
Summary
The formation of hadrons out of quarks (“hadronization”) represents a fundamental process in nature that can be investigated at particle colliders where, at high collision energies, quarks represent the relevant degrees of freedom for a very short time on the order of 10−23 s. The following hadronic decay channels are reconstructed to measure the production of the Σ0c;þþ, Λþc , and D0 particles and their antiparticles. The measurements of the D0 and Λþc cross sections are based on an invariant-mass analysis of signal candidates selected for having the proper daughter-particle identities and a displaced decay topology.
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