An extended segment pattern dictionary for pattern matching tracking algorithm at BESIII

A pattern matching based tracking algorithm, named MdcPatRec, is used for the reconstruction of charged tracks in the drift chamber of the BESIII detector. This paper addresses the shortage of segment finding in MdcPatRec algorithm. An extended segment construction scheme and the corresponding pattern dictionary are presented. Evaluation with Monte-Carlo and experimental data show that the new method can achieve higher efficiency for low transverse momentum tracks.

Observation of chi_{cJ} Decays to Lambda Lambda barpi^{+}pi^{-}

Decays of the chi_{cJ} states (J=0, 1, 2) to Lambda Lambda bar pi^{+} pi^{-}, including processes with intermediate Sigma(1385), are studied through the E1 transition psi-->gamma chi_{cJ} using 106 million psi events collected with the BESIII detector at BEPCII. This is the first observation of chi_{cJ} decays to the final state LambdaLambda bar pi^{+}pi^{-}. The branching ratio of the intermediate process chi_{cJ}-->Sigma(1385)^{+/-} bar{Sigma}(1385)^{-/+} is also measured for the first time, and the results agree with the theoretical predictions based on the color-octet effect.