High-statistics measurements of differential cross sections and spin density matrix elements for the reaction γp → ϕp have been made using the CLAS detector at Jefferson Lab. We cover center-of-mass energies (√s) from 1.97 to 2.84 GeV, with an extensive coverage in the ϕ production angle. The high statistics of the data sample made it necessary to carefully account for the interplay between the ϕ natural lineshape and effects of the detector resolution, that are found to be comparable in magnitude. We study both the charged- (ϕ → K⁺K^-) and neutral- (ϕ → K[0 over S]K[0 over L]) K[⎯⎯⎯ over K] decay modes of the ϕ. Further, for the charged mode, we differentiate between the cases where the final K^- track is directly detected or its momentum reconstructed as the total missing momentum in the event. The two charged-mode topologies and the neutral-mode have different resolutions and are calibrated against each other. Extensive usage is made of kinematic fitting to improve the reconstructed ϕ mass resolution. Our final results are reported in 10- and mostly 30-MeV-wide √s bins for the charged- and the neutral-modes, respectively. Possible effects from K⁺Λ^* channels with pK[⎯⎯⎯ over K] final states are discussed. These present results constitute the most precise and extensive ϕ photoproduction measurements to date and in conjunction with the ω photoproduction results recently published by CLAS, will greatly improve our understanding of low energy vector meson photoproduction.

Exclusive neutral-pion electroproduction (ep → e^'p^'π⁰) was measured at Jefferson Lab with a 5.75-GeV electron beam and the CLAS detector. Differential cross sections d⁴σ/dtdQ²dx_Bdϕ_π and structure functions σ_T + εσ_L, σ_TT, and σ_LT as functions of t were obtained over a wide range of Q² and x_B. The data are compared with Regge and handbag theoretical calculations. Analyses in both frameworks find that a large dominance of transverse processes is necessary to explain the experimental results. For the Regge analysis it is found that the inclusion of vector meson rescattering processes is necessary to bring the magnitude of the calculated and measured structure functions into rough agreement. In the handbag framework, there are two independent calculations, both of which appear to roughly explain the magnitude of the structure functions in terms of transversity generalized parton distributions.