Elastic Electroproduction of $\rh0$ and $J/\Psi$ Mesons at large $Q^2$ at HERA

Abstract

The total cross sections for the elastic electroproduction of $\rh0$ and $J/\Psi$ mesons for $Q^2$ $>$ 8 GeV${}^2$ and $<W>\simeq 90$ GeV/c${}^2$ are measured at HERA with the H1 detector. The measurements are for an integrated electron$-$proton luminosity of $\simeq$~3~pb${}^{-1}$. The dependences of the total virtual photon$-$proton (${\gamma }^{\ast }p$) cross sections on $Q^2$, $W$ and the momentum transfer squared to the proton ($t$), and, for the $\rho$, the dependence on the polar decay angle ($\cos {\theta }^{\ast }$), are presented. The $J/\Psi$ : $\rh0$ cross section ratio is determined. The results are discussed in the light of theoretical models and of the interplay of hard and soft physics processes.

29 pages, latex, 7 Figures appended as uuencoded file