The complete analysis of reaction gamma p -> pi^+ K^-K^+ n at JLab
Lei Guo
JLab

The reaction $\gamma p \rightarrow \pi^+K^-K^+n$ has been investigated at Jefferson Lab using a tagged photon beam with an energy range of 3-5.47~GeV. A possible narrow baryon state with strangeness S=+1 and mass $M=1555\pm 7\pm 10$~MeV/c$^2$ was observed in the $nK^+$ invariant mass spectrum. The width of peak is consistent with the CLAS resolution (FWHM=26~MeV/c$^2$), and its statistical significance is 7.8 $\pm$ 1.0 ~$\sigma$. Partial Wave Analysis was performed for the three-body mesonic background with the energy range of 4.8-5.47~GeV. The analysis demonstrates that the observed signal is unlikely to arise from meson production in the same final state. Interesting features were also observed in the $2^-$, $1^-$ and $1^+$ partial wave intensity distributions.