| We studied the reaction ep → e 'p'&phis; with a 4.2 GeV incident electron beam in the region of the electroproduction variables Q 2 from 0.7 to 2.2 GeV2 and W from 2.0 to 2.6 GeV. The data were taken and analyzed at the Thomas Jefferson National Accelerator Facility. For the first time, we observe the expected t-slope dependence on Q2 and Deltatau in &phis; vector meson production. We find that the width of the forward &phis;-meson diffraction peak increases rapidly as the interaction time decreases below cDeltatau ≈ 1 fm. Within a simple optical model framework, the data show that &phis; meson has a smaller size than the rho. The measured &phis; cross-section dependence on Q2 is in a good agreement with previous measurements and well-described by the phenomenological Pomeron-exchange model. Our cross-section data do not favor the standard Vector Meson Dominance and ss-knockout model predictions. From the angular distribution of the decay &phis; → K+K--, assuming the s-channel helicity conservation, we extracted the longitudinal-to-transverse cross-section ratio, R, and Vector Meson Dominance scaling parameter, xi2, which are consistent with the previous measurements and the model expectations.; This work was supported by the TJNAF and SURA Graduate Student Fellowship Program. |
