# Pomeron, nucleon-resonance, and $(0^+,0^-,1^+)$-meson contributions in $\phi$-meson photoproduction

## TL;DR

This paper models the reaction mechanism of $\, ext{phi}$-meson photoproduction off protons up to 2.8 GeV, incorporating various meson exchanges and nucleon resonances to explain experimental cross sections and spin observables.

## Contribution

It introduces a comprehensive effective Lagrangian model including Pomeron, meson exchanges, and nucleon resonances to analyze $\, ext{phi}$-meson photoproduction, providing detailed numerical results.

## Key findings

- Pomeron and meson-resonance contributions are crucial for matching experimental data.
- Interference effects between mesonic and baryonic contributions are significant.
- The model successfully reproduces differential cross sections and spin-density matrices.

## Abstract

We investigate the reaction mechanism of the $\phi$-meson photoproduction off the proton target, i.e., $\gamma p\to\phi p$, up to $\sqrt{s}=2.8$ GeV. For this purpose, we employ an effective Lagrangian approach in the tree-level Born approximation, and we employ various experimental and theoretical inputs. As a theoretical setup, the vectorlike Pomeron ($C=+1$) is taken into account as a parameterized two-gluon exchange contribution. We also consider $f_1(1285)$ axial-vector-meson, ($\pi,\eta$) pseudoscalar-meson, and ($a_0,f_0$) scalar-meson exchanges in the $t$ channel, in addition to the experimentally confirmed nucleon resonances, such as $N^*(2000,5/2^+)$ and $N^*(2300,1/2^+)$, for the direct $\phi$-meson radiations in the $s$ and $u$ channels. We provide numerical results for the total and differential cross sections as well as the spin-density matrices in the Gottfried-Jackson, Adair, and helicity frames. We observe that, together with the universally accepted pomeron contribution, the considered meson and nucleon-resonance contributions play significant roles in reproducing the experimental data for the forward and backward $\phi$-meson scattering-angle regions, respectively, indicating the nontrivial interferences between mesonic and baryonic contributions.