Forward coherent $ϕ$-meson photoproduction from deuterons near threshold

Chang, W. C.; Horie, K.; Shimizu, S.; Miyabe, M.; Ahn, D. S.; Ahn, J. K.; Akimune, H.; Asano, Y.; Date, S.; Ejiri, H.; Fukui, S.; Fujimura, H.; Fujiwara, M.; Hasegawa, S.; Hicks, K.; Hotta, T.; Imai, K.; Ishikawa, T.; Iwata, T.; Kato, Y.; Kawai, H.; Kim, Z. Y.; Kino, K.; Kohri, H.; Kumagai, N.; Lin, P. J.; Makino, S.; Matsuda, T.; Matsumura, T.; Matsuoka, N.; Mibe, T.; Miyachi, Y.; Morita, M.; Muramatsu, N.; Nakano, T.; Niiyama, M.; Nomachi, M.; Ohashi, Y.; Ohkuma, H.; Ooba, T.; Oshuev, D. S.; Rangacharyulu, C.; Sakaguchi, A.; Sasaki, T.; Shagin, P. M.; Shiino, Y.; Shimizu, A.; Shimizu, H.; Sugaya, Y.; Sumihama, M.; Toi, Y.; Toyokawa, H.; Wakai, A.; Wang, C. W.; Wang, S. C.; Yonehara, K.; Yorita, T.; Yoshimura, M.; Yosoi, M.; Zegers, R. G. T.

Forward coherent $ϕ$-meson photoproduction from deuterons near threshold

Authors

Description

Differential cross sections and decay asymmetries for coherent $ϕ$-meson photoproduction from deuterons were measured for the first time at forward angles using linearly polarized photons at $E_γ$= 1.5-2.4 GeV. This reaction offers a unique way to directly access natural-parity Pomeron dynamics and gluon exchange at low energies. The cross sections at zero degrees increase with increasing photon energy. The decay asymmetries demonstrate a complete dominance of natural-parity exchange processes, showing that isovector unnatural-parity $π$-meson exchange is small. Nevertheless the deduced cross sections of $ϕ$-mesons from nucleons contributed by isoscalar t-channel exchange processes are not well described by the conventional Pomeron model.
14 pages, 6 figures. Final published version