2022 Impact factor 4.4
Particles and Fields
Eur. Phys. J. C 27, 87-99 (2003)
DOI: 10.1140/epjc/s2002-01106-2

$J/\psi$ production at HERA in the color singlet model with kT-factorization

A.V. Lipatov1 and N.P. Zotov2

1  Physical Department, M.V. Lomonosov Moscow State University, 119992 Moscow, Russia
2  D.V. Skobeltsyn Institute of Nuclear Physics, M.V. Lomonosov Moscow State University, 119992 Moscow, Russia

(Received: 31 October 2002 / Published online: 24 January 2003 )

In the framework of the kT-factorization QCD approach and the color singlet model we consider $J/\psi$ inelastic photo- and leptoproduction processes at HERA. We investigate the dependences of the single differential and double differential cross section on various forms of the unintegrated gluon distribution. The z and ${\vec p}_{\mathrm
{T}}$ dependences of the spin alignment parameter $\alpha$ are presented also. Our theoretical predictions agree well with the recent data taken by the H1 and ZEUS collaborations at HERA. It is shown that the experimental study of the polarization $J/\psi$ mesons at the low value $Q^2 < 1\,{\mathrm
{GeV}}^2$ is an additional test of BFKL gluon dynamics.

© Società Italiana di Fisica, Springer-Verlag 2003