Kinematic Fitting of Detached Vertices

The eg3 experiment at the Jefferson Lab CLAS detector aims to determine the existence of the $\Xi_{5}$ pentaquarks and investigate the excited $\Xi$ states. Specifically, the exotic $\Xi_{5}^{--}$ pentaquark will be sought by first reconstructing the $\Xi^{-}$ particle through its weak decays, $\Xi^{-}\to\pi^{-}\Lambda$ and $\Lambda\to\pi^{-}$. A kinematic fitting routine was developed to reconstruct the detached vertices of these decays, where confidence level cuts on the fits are used to remove background events. Prior to fitting these decays, the exclusive reaction $\gamma D\rightarrow pp\pi^{-}$ was studied in order to correct the track measurements and covariance matrices of the charged particles. The $\Lambda\rightarrow p\pi^{-}$ and $\Xi^{-}\to\pi^{-}\Lambda$ decays were then investigated to demonstrate that the kinematic fitting routine reconstructs the decaying particles and their detached vertices correctly.