Speaker
Nataliia Kovalchuk
(Hamburg University (DE))
Description
The exclusive deep inelastic electroproduction of $\psi(2S)$ and $J/\psi$ has been studied with the ZEUS detector at HERA in the kinematic range $2 \le Q^2 \le 80$ GeV$^2$, $30 \le W \le 210$ GeV and $|t| \le 1$ GeV$^2$, where $Q^2$ is the photon virtuality, $W$ is the photon-proton centre-of-mass energy and $t$ is the squared four-momentum transfer at the proton vertex. The data for $2 \le Q^2 \le 5$ GeV$^2$ were taken in the HERA I running period and correspond to an integrated luminosity of 114 pb$^{-1}$.
The data for $5 \le Q^2 \le 80$ GeV$^2$ are from both HERA I and HERA II periods and correspond to an integrated luminosity of 468 pb$^{-1}$. The decay modes analysed were $\mu^+\mu^-$ and $J/\psi \pi^+\pi^-$ for the $\psi(2S)$ and $\mu^+\mu^-$ for the $J/\psi$ and the cross-section ratio $\sigma(\psi(2S))/\sigma(J/\psi)$ has been measured as a function of $Q^2, W$ and $t$. The measurement is compared to predictions of QCD-inspired models of vector-meson production.
Author
Matthew Wing
(UCL)
