Spin effects and baryon resonance dynamics in phi-meson photoproduction at few GeV

Abstract

The diffractive $\varphi$-meson photoproduction amplitude is dominated by the Pomeron exchange process and contains the terms that govern the spin-spin and spin-orbital interactions. We show that these terms are responsible for the spin-flip transitions at forward photoproduction angles and appear in the angular distributions of $\varphi \to K^{+}{K}^{-}$ -decay in reactions with unpolarized and polarized photon beams. At large momentum transfers, the main contribution to the $\varphi$-meson photoproduction is found to be due to the excitation of nucleon resonances. Combined analysis of $\omega$ and $\varphi$ photoproduction indicates strong OZI-rule violation in $\varphi N{N}^{\ast }$ - couplings. We also show that the spin observables are sensitive to the dynamics of $\varphi$-meson photoproduction at large angles and could help distinguish different theoretical models of nucleon resonances. Predictions for spin effects in $\varphi$-meson photoproduction are presented for future experimental tests.

39 pages, 21 figures. Submitted to the Physical Review C