Leptoproduction of J/ψ

Abstract

I review the status of the extraction of NRQCD color-octet $J/\psi$ production matrix elements. Large theoretical uncertainties in current extractions from hadroproduction and photoproduction are emphasized. Leptoproduction of $J/\psi$ is calculated within the NRQCD factorization formalism. Color-octet contributions dominate the cross section, allowing for a reliable extraction of $<{\mathcal{O}}_8^{J/\psi }{(}^1{S}_0)>$ and $<{\mathcal{O}}_8^{J/\psi }{(}^3{P}_0)>$. A comparison with preliminary data from the H1 collaboration shows that leading order color-octet mechanisms agree with the measured total cross section for $Q^2>4m_c^2$, while the color-singlet model underpredicts the cross section by a factor of 5.

5 pages, 2 figures, Talk given at XXIX International Conference on High Energy Physics, Vancouver