Based on real data,a new parameterized model of the main drift chamber response is proposed.In this model,we tune the ratio of good hits and the residual distribution separately.By data quality checking,the diference between simulation and data in track reconstruction efciency reduces from 1%to 0.5%averagely for the pion in J/ψ→π+ππ0,and the momentum resolution agreement improves significantly for the proton in J/ψ→ppˉ.
Using experimental data, Monte Carlo tuning is implemented for performance parameters associated with the scintillation counters and readout electronics of the BESⅢ time-of-flight(TOF) system, as part of the full simulation model. The implementation of the tuning is described for simulations designed to reproduce the performance of a number of TOF system parameters, including pulse height, hit efficiency, time resolution, dead channels and background. In addition, comparisons with experimental data are presented.
The P-wave charm-strange mesons Ds0(2317) and Ds1(2460) lie below the DK and D*K threshold respectively. They are extremely narrow because their strong decays violate the isospin symmetry. We study the possible heavy molecular states composed of a pair of excited charm strange mesons. As a byproduct, we also present the numerical results for the bottonium-like analogue.
研究了BESⅢ漂移室(MDC)时间测量道的性能,包括空间分辨、动量分辨、击中效率、噪声率和Bhabha事例重建效率等。并用2011年的Bhabha事例样本对MDC性能作了run by run监测,研究了引起数据质量变化的各种因素。另外还研究了工作高压丢失(trip)对MDC性能的影响,此外,为了提高数据质量开发了相应软件包以去掉受高压丢失影响的事例。
We study possible exotic J^(PC)=0^+- states using tetraquark interpolating currents with the QCD sum rule approach. The extracted masses are around 4.85GeV for the charmonium-like states and 11.25 GeV for the bottomonium-like states. There is no working region for the light tetraquark currents, which implies that the light 0^+- state may not exist below 2GeV.
The number of ψ' events accumulated by the BESⅢ experiment from March 3 through April 14, 2009, is determined by counting inclusive hadronic events. The result is 106.41×(1.00±0.81%)×106 . The error is systematic dominant; the statistical error is negligible.
