Differential cross sections and spin density matrix elements for γ p → φ p from CLAS

Preliminary differential cross-sections and the ρ0 MM spin density matrix elements (SDME) for the reaction γ p → φ p for both charged- (φ → K+K−) and neutral-mode (φ → K0 LK0 S ) topologies obtained from CLAS are presented. Our kinematic coverage is from near production threshold (√s ∼ 1.97 GeV) to √s = 2.84 GeV, with a wide coverage in the production angle. As seen in previous LEPS results, the differential cross-sections show a localized “bump” between √s ∼ 2 and 2.2 GeV that is not expected from a simple Pomeron exchange picture. Comparisons between the charged- and neutral-mode results and possible effects from the K+Λ(1520) channel are discussed. Our SDME results confirm the well-known deviations from t-channel helicity conservation (TCHC) for Pomeron exchange, but s-channel helicity conservation (SCHC) is also seen to be broken.