Search for the $\hat{I}{˜}^{+}$ pentaquark via the $\ddot{I}{€}^{-}p\to K^{-}X$ reaction at 1.92 GeV/$c$

Abstract

The $\hat{I}{˜}^{+}$ pentaquark baryon was searched for via the $\ddot{I}{€}^{-}p\to K^{-}X$ reaction in a missing-mass resolution of 1.4 MeV/$c^2$(FWHM) at J-PARC. $\ddot{I}{€}^{-}$ meson beams were incident on the liquid hydrogen target with the beam momentum of 1.92 GeV/$c$. No peak structure corresponding to the $\hat{I}{˜}^{+}$ mass was observed. The upper limit of the production cross section averaged over the scattering angle of 2${}^{\circ }$ to 15${}^{\circ }$ in the laboratory frame was obtained to be 0.26 $\hat{I}¼$b/sr in the mass region of 1.51$-$1.55 GeV/$c^2$.The upper limit of the $\hat{I}{˜}^{+}$ decay width using the effective Lagrangian approach was obtained to be 0.72 MeV/$c^2$ and 3.1 MeV/$c^2$ for $J_{\hat{I}}^P˜=1/2^{+}$ and $J_{\hat{I}}^P˜=1/2^{-}$, respectively.

5 pages, 3 figures, 1 table