Study Of Ψ’â†'ΛΣ+Ï€-+c.c.on BESâ…¢

Charmonium physics is an important research field in particle physics.The generation and decay processes of charmonium particles are closely related with QCD dynamics.It is very important for testing and developping QCD theory.The ψ’particle is a very important member of the charmonium family.The measurement of branching ratios to ψ’â†'A∑+Ï€-+c.c.is very signnificance.At present,BESIII collected the world’s largest(106.32士0.98)×106data samples of ψ’,and it Will provide us a good opportunity to study the charmonium decays and search for new physics.The Beijing Spectrometer III(BESIII)detector is large,general purpose,high accu-racy spectrometer which is working on Beijing Electron Positron Collider(BEPCII).BE-Sâ…¢ which is working at the energy range of tau-charm is mainly to study the electro-weak interaction.strong interaction and search for new physics. In this paper:using an (106.32土0.98)×106data samples at Ecms=3.686GeV which is collected by BES-III de-tector at BEPC-II in March and April2009. The six channels of ψ’â†'A∑+Ï€-+c.c.have been carefully studied. First,after analysis and calculation of the character of the final particles and the event selection criteria are also studied carefully. Then,for the event selection and using Roofit to fit the selected samples. Finally,get good samples. At the same time.background and error were analyzed and very elear excited baryon states signals∑(1385).∑(1660).∑(1670).A(1520).A(1670).A(1690) were observed,and so on.Their branching ratios were measured for the first time.Their branching ratios are determined to be, B(ψ’â†'A∑+Ï€-â†'pÏ€-nÏ€+Ï€-)=(6.91±0.25±0.45)×10-5, B(ψ’â†'A∑-Ï€+â†'pÏ€-nÏ€-Ï€+)=(7.93±0.36±0.44)×10-5， B(ψ’â†'A∑+Ï€-â†'pÏ€+nÏ€+Ï€-)=(7.64±0.35±0.44)×10-5, B(ψ’â†'A∑-Ï€+â†'pÏ€+nÏ€-Ï€+)=(7.05±0.33±0.36)×10-5, B(ψ’â†'A∑-Ï€+â†'pÏ€-nÏ€0Ï€+)=(7.29±0.47±0.53)×10-5, B(ψ’â†'A∑+Ï€-â†'pÏ€+nÏ€0Ï€-)=(7.68±0.67±0.47)×10-5,where the first error is statistical and the second one is systematic.