Observation of an ExoticS=+1Baryon in Exclusive Photoproduction from the Deuteron

In an exclusive measurement of the reaction $\ensuremath{\gamma}d\ensuremath{\rightarrow}{K}^{+}{K}^{\ensuremath{-}}pn$, a narrow peak that can be attributed to an exotic baryon with strangeness $S=+1$ is seen in the ${K}^{+}n$ invariant mass spectrum. The peak is at $1.542\ifmmode\pm\else\textpm\fi{}0.005\text{ }\text{ }\mathrm{G}\mathrm{e}\mathrm{V}/{c}^{2}$ with a measured width of $0.021\text{ }\text{ }\mathrm{G}\mathrm{e}\mathrm{V}/{c}^{2}$ FWHM, which is largely determined by experimental mass resolution. The statistical significance of the peak is $(5.2\ifmmode\pm\else\textpm\fi{}0.6)\ensuremath{\sigma}$. The mass and width of the observed peak are consistent with recent reports of a narrow $S=+1$ baryon by other experimental groups.

Observation of an ExoticS=+1Baryon in Exclusive Photoproduction from the Deuteron | Litlas