Photoproduction of $K^+K^-$ meson pairs on the proton

TL;DR

This study investigates the photoproduction of $K^+K^-$ pairs on the proton, analyzing angular distributions and cross sections to understand meson production mechanisms, including the first measurement of the $S$-wave contribution's $t$-dependence.

Contribution

It provides new measurements of the $t$-dependent cross section of the $S$-wave in $K^+K^-$ photoproduction and compares these with Regge-inspired model predictions.

Findings

Evidence for $S-P$ interference in $K^+K^-$ production.

First measurement of the $t$-dependent $S$-wave cross section.

Dominant $ ext{phi}$ meson contribution in $P$-wave.

Abstract

The exclusive reaction $\gamma p \to p K^+ K^-$ was studied in the photon energy range $3.0 - 3.8 \mbox{ GeV}$ and momentum transfer range $0.6<-t<1.3 \mbox{ GeV}^2$. Data were collected with the CLAS detector at the Thomas Jefferson National Accelerator Facility. In this kinematic range the integrated luminosity was approximately 20 pb$^{-1}$. The reaction was isolated by detecting the $K^+$ and the proton in CLAS, and reconstructing the $K^-$ via the missing-mass technique. Moments of the di-kaon decay angular distributions were extracted from the experimental data. Besides the dominant contribution of the $\phi$ meson in the $P$-wave, evidence for $S-P$ interference was found. The differential production cross sections $d\sigma/dt$ for individual waves in the mass range of the $\phi$ resonance were extracted and compared to predictions of a Regge-inspired model. This is the first time the $t$-dependent cross section of the $S$-wave contribution to the elastic $K^+K^-$ photoproduction has been measured.