Exclusive photoproduction of the cascade (Ξ) hyperons

Abstract

We report on the first measurement of exclusive ${\ensuremath{\Xi}}^{\ensuremath{-}}(1321)$ hyperon photoproduction in $\ensuremath{\gamma}p\ensuremath{\rightarrow}{K}^{+}{K}^{+}{\ensuremath{\Xi}}^{\ensuremath{-}}$ for $3.2<{E}_{\ensuremath{\gamma}}<3.9$ GeV. The final state is identified by the missing mass in $p(\ensuremath{\gamma},{K}^{+}{K}^{+})X$ measured with the CLAS detector at Jefferson Laboratory. We have detected a significant number of the ground state ${\ensuremath{\Xi}}^{\ensuremath{-}}(1321){\frac{1}{2}}^{+}$ and have estimated the total cross section for its production. We also have strong evidence for the first excited state ${\ensuremath{\Xi}}^{\ensuremath{-}}(1530){\frac{3}{2}}^{+}$. Photoproduction provides a copious source of \ensuremath{\Xi}'s. We discuss the possibilities of a search for the recently proposed ${\ensuremath{\Xi}}_{5}^{\ensuremath{-}}$ and ${\ensuremath{\Xi}}_{5}^{+}$ pentaquarks.