2019 Impact factor 4.389
Particles and Fields

Eur. Phys. J. C 25, 41-53 (2002)
DOI: 10.1007/s10052-002-01014-y

Inelastic leptoproduction of $J/\psi$ mesons at HERA

The H1 Collaboration

(Received: 21 May 2002 / Revised version: 16 June 2002 / Published online: 26 July 2002 )

The leptoproduction of $J/\psi$ mesons is studied in inelastic reactions for four momentum transfers $2<Q^2<100\mbox{GeV}^2$. The data were taken with the H1 detector at the electron proton collider HERA and correspond to an integrated luminosity of $77\,\mbox{pb}^{-1}$. Single differential and double differential cross sections are measured with increased precision compared with previous analyses. New leading order calculations within the non-relativistic QCD factorisation approach including colour octet and colour singlet contributions are compared with the data and are found to give a reasonable description of most distributions. An exception is the shape of the distribution in the $J/\psi$ fractional energy, z, which deviates significantly from that of the data. Comparisons with photoproduction are made and the polarisation of the produced $J/\psi$ meson is analysed.

© Società Italiana di Fisica, Springer-Verlag 2002