An alternative explanation for the $\Theta (1540)$ pentaquark peak

Abstract

We have studied the $\gamma d\to K^{+}{K}^{-}np$ reaction in which the LEPS collaboration found a signal in the $K^{+}n$ invariant mass for the claimed $\Theta (1540)$ pentaquark peak. Our study reveal that the procedure used at LEPS to reconstruct the $K^{+}n$ invariant mass generates an artificial strength in the $\Theta (1540)$ region and that the LEPS collaboration underestimated the background in that region, such that the signal observed for the $\Theta (1540)$ is compatible with a fluctuation of $2\sigma$ over the calculated background.

Comments: Proceeding for the CHIRAL 10 workshop, Valencia (Spain), June 21-24 2010