Upper limits for the photoproduction cross section for the ${\ensuremath{\Phi}}^{\ensuremath{-}\ensuremath{-}}(1860)$ pentaquark state off the deuteron

Upper limits for the photoproduction cross section for the $Φ^{- -} (1860)$ pentaquark state off the deuteron

H. Egiyan et al. (CLAS Collaboration)

Phys. Rev. C 85, 015205 – Published 30 January 2012

Abstract

We searched for the $Φ^{- -} (1860)$ pentaquark in the photoproduction process off the deuteron in the $Ξ^{-} π^{-}$ -decay channel using CLAS. The invariant-mass spectrum of the $Ξ^{-} π^{-}$ system does not indicate any statistically significant enhancement near the reported mass $M = 1.860$ GeV. The statistical analysis of the sideband-subtracted mass spectrum yields a $90 %$ -confidence-level upper limit of 0.7 nb for the photoproduction cross section of $Φ^{- -} (1860)$ with a consecutive decay into $Ξ^{-} π^{-}$ in the photon-energy range $4.5 G e V < E_{γ} < 5.5 G e V$ .