Intrinsic charm in the nucleon and charm production at large rapidities in collinear, hybrid and k T -factorization approaches
Abstract We discuss the role of intrinsic charm (IC) in the nucleon for forward production of c-quark (or c ¯ $$ \overline{c} $$ -antiquark) in proton-proton collisions for low and high energies. The calculations are performed in collinear-factorization approach with on-shell partons, k T -factoriza...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
SpringerOpen
2020-10-01
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| Series: | Journal of High Energy Physics |
| Subjects: | |
| Online Access: | http://link.springer.com/article/10.1007/JHEP10(2020)135 |
| Summary: | Abstract We discuss the role of intrinsic charm (IC) in the nucleon for forward production of c-quark (or c ¯ $$ \overline{c} $$ -antiquark) in proton-proton collisions for low and high energies. The calculations are performed in collinear-factorization approach with on-shell partons, k T -factorization approach with off-shell partons as well as in a hybrid approach using collinear charm distributions and unintegrated (transverse momentum dependent) gluon distributions. For the collinear-factorization approach we use matrix elements for both massless and massive charm quarks/antiquarks. The distributions in rapidity and transverse momentum of charm quark/antiquark are shown for a few different models of IC. Forward charm production is dominated by gc-fusion processes. The IC contribution dominates over the standard pQCD (extrinsic) gg-fusion mechanism of c c ¯ $$ c\overline{c} $$ -pair production at large rapidities or Feynman-x F . We perform similar calculations within leading-order and next-to-leading order k T -factorization approach. The k T -factorization approach leads to much larger cross sections than the LO collinear approach. At high energies and large rapidities of c-quark or c ¯ $$ \overline{c} $$ -antiquark one tests gluon distributions at extremely small x. The IC contribution has important consequences for high-energy neutrino production in the Ice-Cube experiment and can be, to some extent, tested at the LHC by the SHIP and FASER experiments by studies of the ν τ neutrino production. |
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| ISSN: | 1029-8479 |