BESIIIΨ(3770)数据的BEPCII质心系束流能量刻度

BEPCII Center-of-mass Beam Energy Calibration for Ψ(3770) Data

截至2011年5月,BESIII探测器在BEPCII对撞机质心系能量3.773 GeV附近采集了2.9fb-1积分亮度的数据。对这些数据进行物理分析,需要对BEPCII的束流能量(Eb)进行刻度。用预期束流能量计算mKnπ的束流约束质量(mbc),拟合束流约束质量谱得到D介子质量(mD(fit))来刻度Eb。对全部Ψ(3770)数据进行了束流能量刻度,并检验刻度后的D介子质量和分辨(σD)。结果表明,用刻度后的束流能量得到的D介子质量更接近D介子的真实质量,且分辨得到进一步改善。

As of May 2011, BESIII has accumulated an integrated data sample of -2.9 fb^-1 around center- of - mass energy of 3. 773 GeV at BEPCII. To analyze these data, it is needed to calibrate the BEPCII beam energy （ Eb）. The expected beam energy was used to calculate the beam constraint mass （ mbc ） of mKnπ combinations and the beam energy was obtained using the fitted mass of D meson （ mo （fit） ） by fitting mbc distribution. The beam energy calibration for all the ψ（3770） data has been performed and the calibrated beam energy has been used to check the mass of D meson as well as the resolution （σD）. The result shows that the fitted mass of D meson with the calibrated beam energy is closer to the true mass of D meson, and the resolution is further improved.