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.
Highlights
Data on light quark mesons comes mainly from hadron induced reactions, e.g., by using K, π, p or pbeams, from decays of heavy mesons and more recently from experiments making use of electromagnetic probes
We have focused on this mass region because it is dominated by the production of the φð1020Þ resonance that decays to the two kaons in the P wave, and a partial wave analysis based on the lower (S and P) waves efficiently describes it
As a check of the analysis procedure, the differential cross section dσ=dt for the γp → pφð1020Þ meson was extracted by integrating the hY00i moment in each t bin in the range 1.005 GeV < MKþK− < 1.035 GeV after subtracting a first-order polynomial background fitted to the data
Summary
Data on light quark mesons comes mainly from hadron induced reactions, e.g., by using K, π, p or pbeams, from decays of heavy mesons and more recently from experiments making use of electromagnetic probes. The f0ð980Þ is difficult to classify and its composition is affected by proximity to the KKthreshold These states have been the subject of extensive investigations [21,22] since their observation in photon-induced reactions can provide insights into their internal structure. In this paper we present results of the analysis of KþK− photoproduction in the photon energy range 3.0–3.8 GeV and momentum transfer squared −t between 0.6 GeV2 and 1.3 GeV2, where the dikaon effective mass MKþK− varies from 0.990 to 1.075 GeV. We have focused on this mass region because it is dominated by the production of the φð1020Þ resonance that decays to the two kaons in the P wave, and a partial wave analysis based on the lower (S and P) waves efficiently describes it.
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