Data Quality Check And Beam Energy Calibration For ψ/(3770) Data And Dalitz Analysis Of The Decay D~0â†'Kπη

From Jan2010to May2011, BESIII has accumulated an integrated data sample of～2.9fb-1around center-of-mass energy of3.773GeV at BEPCII for analyzing Ψ(3770) and D physics systematically. Statistic errors can be decreased for increasing the number of D meson from Ψ(3770) decay. However, many measurements are depended on the systematic error, so the quality of Ψ(3770) data is important to get an accurate measurement. In this paper, we check the quality of offline Ψ(3770) data by the accuracy of integrated luminosity, the stability of the ratio between signal yield and luminosity and the performance of vertex, dE/dx, TOF and EMC. The result shows that the quality of all Ψ(3770) data in BESIII is well. It is necessary to make a correction of dE/dx offline calibration and TOF correction. To analyze these data, it is necessary that we calibrate the BEPCII beam energy (Eb). An expected beam energy1.8865GeV was used to calculate the beam constraint mass (mbc) of mKnÏ€ combination, then fitting the mbc distribution to calibrate the beam energy using the fitted mass of D meson (mD(fit)). We calibrate all the Ψ(3770) data and use this calibrated beam energy to get the mass of D meson as well as the resolution (σD). The result shows that the fitted mass of D meson with calibrated beam energy is closer to the true mass of D meson given by PDG2010, and the resolution is further improved.Double tag D meson was used to analyze the Dalitz plot of D0â†'Ï€+η. At first, we use exclusive Monte Carlo to calculate the efficiency of event reconstruction and event selection. With no regard for the affection of mis-reconstruction, the efficiency of event reconstruction and event selection is12.90%. Then, we use inclusive Monte Carlo and all of BESIII Ψ(3770) data to analyze the construction of signal and background in the selected events. For all BESIII Ψ(3770) data, the number of signal events and background in side band are2517±58and451±21, respectively. Furthermore, we have calculated the efficiency by Dalitz plot analysis.