Interference effect between $\phi$ and $\Lambda(1520)$ production channels in the $\gamma p \rightarrow K^+K^-p$ reaction near threshold

TL;DR

This study measures the interference between $\

Contribution

First measurement of $\\phi$-$\\Lambda(1520)$ interference in $\\gamma p \\to K^+K^-p$, revealing phase relations and implications for exotic states near threshold.

Findings

Constructive interference at forward angles for $K^+K^-$ pairs.

Destructive interference at forward angles for proton emission.

Interference does not explain the 2.1 GeV bump in cross sections.

Abstract

The $\phi$-$\Lambda(1520)$ interference effect in the $\gamma p\to K^+K^-p$ reaction has been measured for the first time in the energy range from 1.673 to 2.173 GeV. The relative phases between $\phi$ and $\Lambda(1520)$ production amplitudes were obtained in the kinematic region where the two resonances overlap. The measurement results support strong constructive interference when $K^+K^-$ pairs are observed at forward angles, but destructive interference for proton emission at forward angles. Furthermore, the observed interference effect does not account for the $\sqrt{s}=2.1$ GeV bump structure in forward differential cross sections for $\phi$ photoproduction. This fact suggests possible exotic structures such as a hidden-strangeness pentaquark state, a new Pomeron exchange and rescattering processes via other hyperon states.