Photo-production of neutral kaons on 12C in the threshold region

Abstract

Kaon photo-production process on ${}^{12}$C has been studied by measuring neutral kaons in a photon energy range of 0.8$-$1.1 GeV. Neutral kaons were identified by the invariant mass constructed from two charged pions emitted in the $K_S^0\to \ddot{I}{€}^{+}\ddot{I}{€}^{-}$ decay channel. The differential cross sections as well as the integrated ones in the threshold photon energy region were obtained. The obtained momentum spectra were compared with a Spectator model calculation using elementary amplitudes of kaon photo-production given by recent isobar models. Present result provides, for the first time, the information on $n({\hat{I}}^3,K^0)\hat{I}›$ reaction which is expected to play an important role to construct models for strangeness production by the electromagnetic interaction. Experimental results show that cross section of ${}^{12}\mathrm{C}({\hat{I}}^3,K^0)$ is of the same order to that of ${}^{12}\mathrm{C}({\hat{I}}^3,K^{+})$ and suggest that slightly backward $K^0$ angular distribution is favored in the ${\hat{I}}^{3}n\to K^0\hat{I}›$ process.

6 pages, 8 figures