Heavy quark and quarkonium production at CERN LEP2: k T-factorization versus data

• Published in: The European physical journal. C, Particles and fields Vol. 41; no. 2; pp. 163 - 172
• Main Authors: Lipatov, A. V., Zotov, N. P.
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer Nature B.V 01.05.2005
• Subjects: CERN; Error analysis; Factorization; Gluons; Photons; Quantum chromodynamics; Quarks
• ISSN: 1434-6044; 1434-6052
• DOI: 10.1140/epjc/s2005-02176-2

We present calculations of heavy quark and quarkonium production at CERN LEP2 in the kT-factorization QCD approach. Both direct and resolved photon contributions are taken into account. A conservative error analysis is performed. The unintegrated gluon distribution in the photon is obtained from the full CCFM evolution equation. The traditional color-singlet mechanism to describe the non-perturbative transition of a \(Q\bar{Q}\)-pair into a final quarkonium is used. Our analysis covers the polarization properties of heavy quarkonia at moderate and large transverse momenta. We find that the total and differential open charm production cross sections are consistent with the recent experimental data taken by the L3, OPAL and ALEPH collaborations. At the same time the DELPHI data for the inclusive \(J/\psi\) production exceed our predictions, but experimental uncertainties are too large to claim a significant inconsistency. The bottom production in photon-photon collisions at CERN LEP2 is hard to explain within the kT-factorization formalism.