As part of a measurement [E. Anciant et al., Phys. Rev. Lett. 85, 4682 (2000)] of the cross section of ϕ meson photoproduction to high momentum transfer, we measured the polar angular decay distribution of the outgoing K+ in the channel ϕ→K+K− in the ϕ center-of-mass frame (the helicity frame). We find that s-channel helicity conservation (SCHC) holds in the kinematical range where t-channel exchange dominates (up to −t∼2.5GeV2 for Eγ=3.6GeV). Above this momentum, u-channel production of a ϕ meson dominates and induces a violation of SCHC. The deduced value of the ϕNN coupling constant lies in the upper range of previously reported values.
Physical Review C
McCormick, K.; Biselli, Angela; and CLAS Collaboration, "Tensor polarization of the ϕ meson photoproduced at high t" (2004). Physics Faculty Publications. 92.
K. McCormick et al. [CLAS Collaboration], "Tensor polarization of the ϕ meson photoproduced at high t", Physical Review C 69.3 (2004) DOI: 10.1103/PhysRevC.69.032203