Chinese Physics C > 2007, Vol. 31 > Issue(3): 229-231

Extract Signals by Fitting χ²Distribution of the Kinematic Fit

Institute of High Energy Physics, CAS, Beijing 100049, China

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Abstract：
In measuring the ψ(2S) radiative decays at BESⅡ, contribution of the background is serious in most of the final states. To extract the number of signal events, a fit to the χ ²distribution of kinematic fit using signal and background components is proposed. Extensive Monte-Carlo simulations (MCS) are performed, and the results show that the shape of χ ²distribution of the signal channel looks different from those of the background channels, thus it provides us by fitting the χ ²distribution of the data to extract the number of signal events. An input-output test is performed using MCS, and the uncertainty of the fit method is found to be less than 2%.

References

[1]	. Particl Data Group. Phys. Lett., 2004, B592: 612. Ablikim M et al(BES Collab.). Nucl. Instrum. Methods,2005, A552: 344

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PING Rong-Gang, MO Xiao-Hu, DU Shu-Xian, LIU Jing, MA Lian-Liang, SHEN Cheng-Ping, WANG Zhi-Yong and YUAN Chang-Zheng. Extract Signals by Fitting χ ²Distribution of the Kinematic Fit[J]. Chinese Physics C, 2007, 31(3): 229-231.

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Received: 2006-07-10
Revised: 2006-08-17

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1.
沈阳化工大学材料科学与工程学院沈阳 110142

Extract Signals by Fitting χ²Distribution of the Kinematic Fit

Corresponding author:PING Rong-Gang,

Institute of High Energy Physics, CAS, Beijing 100049, China

Received Date:2006-07-10
Accepted Date:2006-08-17
Available Online:2007-03-05

Abstract:In measuring the ψ(2S) radiative decays at BESⅡ, contribution of the background is serious in most of the final states. To extract the number of signal events, a fit to the χ²distribution of kinematic fit using signal and background components is proposed. Extensive Monte-Carlo simulations (MCS) are performed, and the results show that the shape of χ²distribution of the signal channel looks different from those of the background channels, thus it provides us by fitting the χ²distribution of the data to extract the number of signal events. An input-output test is performed using MCS, and the uncertainty of the fit method is found to be less than 2%.