The calibration algorithm for RPC-based muon detector at BESⅢ has been developed. The calibration method, calibration error and algorithm performance are studied. The primary results of efficiency and noise at layer, module and strip levels have been calibrated with cosmic ray data. The calibration constants are available for simulation and reconstruction tuning. The results of Monte Carlo and data are also compared to check the validation and reliability of the algorithm.
The decay channel ψ→π+π-J/ψ(J/ψ→γp) is studied using a sample of 1.06×108 ψ events collected by the BESIII experiment at BEPCII. A strong enhancement at threshold is observed in the p invariant mass spectrum. The enhancement can be fitted with an S-wave Breit-Wigner resonance function with a resulting peak mass of M =1861+6-13 (stat)+7-26 (syst) MeV/c2 and a narrow width that is Γ <38 MeV/c2 at the 90% confidence level. These results are consistent with published BESII results. These mass and width values do not match with well established mesons.
麦迪娜M. N. Achasov安磊安琪安正华白景芝班勇N. Berger边渐鸣I. BoykoR. A. BriereV. Bytev蔡啸曹国富曹学香常劲帆G. Chelkov陈刚陈和生陈江川陈丽平陈玛丽陈鹏陈申见陈元柏初元萍D. Cronin-Hennessy代洪亮代建平D. Dedovich邓子艳I. DenysenkoM. Destefanis丁勇董燎原董明义杜书先段麦英方建封常青傅成栋傅金林高原宁耿聪K. Goetzen龚文煊M. GrecoS. Grishin顾运厅郭爱强郭立波郭玉萍韩少卿F. A. Harris何康林何苗何振亚衡月昆侯治龙胡海明胡继峰胡涛胡小为黄彬黄光明黄金书黄性涛黄燕萍姬长胜纪全季晓斌季筱璐贾卢魁姜丽丽江晓山焦健斌金大鹏金山S. KomamiyaW. KuehnS. Lange梁干庄李澄李翠李德民李飞李刚李海波李捷李家才李蕾李陆李秋菊李卫东李卫国李晓玲李小男李学潜李秀荣李玉晓李志兵梁昊梁泰然Y.T. Liang梁勇飞廖广睿廖小涛刘北江刘春秀刘春燕刘福虎刘芳刘峰刘冠川刘虎刘宏邦刘怀民刘红薇刘健刘觉平刘坤刘魁勇刘树彬刘晓海刘玉斌刘艳芳刘衍文刘勇刘振安鲁公儒吕军光吕绮雯吕晓睿卢云鹏罗成林罗民兴Zhejiang University罗涛罗小兰马长利马凤才马海龙马秋梅马想马骁妍M. Maggiora冒亚军毛泽普闵建莫晓虎N. Yu. MuchnoiY. Nefedov宁飞鹏S. L. Olsen欧阳群M. PelizaeusK. Peters
Cosmic-ray data of 90 M events have been collected and used for calibration,alignment as well as detector tuning. A special tracking algorithm for the BESⅢ muon counter is developed and verified with Monte-Carlo simulation and then further confirmed with the cosmic-ray data. The obtained strip resolutions are in good agreement with the design values. A new alignment approach for the BESⅢ muon counter is confirmed with the cosmic-ray data and proposed to be used in future analysis of experimental data.
Decays of both η and η' provide very useful information in our understanding of low-energy QCD, and experimental signatures for these decays would be extremely helpful at BES-Ⅲ. The rare decays of the η and η' mesons could serve as a low-energy test of the Standard Model and its beyond. The sensitivities of the measurements of η and η' decays are discussed at BES-Ⅲ, in which the η and η' mesons are produced in the ψ decays.
It has been conjectured that the relative phase between strong and electromagnetic amplitudes is universally -90° in charmonium decays. ψ′ decaying into a pseudoscalar pair provides a possibility to test this conjecture. However, the experimentally observed cross section for such a process is depicted by the two-fold integral, which takes into account the initial state radiative (ISR) correction and energy spread effect. Using the generalized linear regression approach, a complex energy-dependent factor is approximated by a linear function of energy. Taking advantage of this simplification, the integration of ISR correction can be performed and an analytical expression with accuracy at the level of 1% is obtained. Then, the original two-fold integral is simplified into a one-fold integral, which reduces the total computing time by two orders of magnitude. Such a simplified expression for the observed cross section usually plays an indispensable role in the optimization of scan data taking, the determination of systematic uncertainty, and the analysis of data correlation.
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.
The number of J/ψ events collected with the BES detector at the BEPC from June 12 to July 28, 2009 is determined to be (225.3 ± 2.8) × 10 6 using J/ψ→inclusive events, where the uncertainty is the systematic error and the statistical one is negligible.
麦迪娜M. N. AchasovD. J. Ambrose安芬芬安琪安正华白景芝班勇J. BeckerN. BergerM. Bertani边渐鸣E. BogerO. BondarenkoI. BoykoR. A. BriereV. Bytev蔡啸A. Calcaterra曹国富常劲帆G. Chelkov陈刚陈和生陈江川陈玛丽陈申见陈晔陈元柏程和平初元萍D. Cronin-Hennessy代洪亮代建平D. Dedovich邓子艳A. DenigI. DenysenkoM. Destefanis丁伟民丁勇董燎原董明义杜书先方建房双世L. FavaF. Feldbauer封常青R. B. Ferroli傅成栋傅金林高原宁耿聪K. Goetzen龚文煊W. GradlM. Greco顾旻皓顾运厅管颖慧郭爱强郭立波郭玉萍韩艳良郝喜庆F. A. Harris何康林何苗何振亚T. Held衡月昆侯治龙胡海明胡继峰胡涛黄彬黄光明黄金书黄性涛黄燕萍T. Hussain姬长胜纪全季晓斌季筱璐贾卢魁姜丽丽江晓山焦健斌焦铮金大鹏金山景繁凡N. Kalantar-NayestanakiM. KavatsyukW. Kuehn赖蔚J. S. Lange潘振声李春花李澄李翠李德民李飞李刚李海波李家才李康李蕾李宁博李秋菊李绍莉李卫东李卫国李晓玲李小男李学潜李秀荣李志兵梁昊梁勇飞梁羽铁廖广瑞廖小涛刘北江C. L. Liu刘春秀刘春燕刘福虎刘芳刘峰刘虎刘宏邦刘汇慧刘怀民刘红薇刘觉平刘魁勇刘凯刘坤刘佩莲刘树彬刘翔刘晓海刘勇刘豫斌刘振安刘志强刘智青H. Loehner鲁公儒吕海江吕军光
Data sets were collected with the BES detector at the BEPC collider at the center-of-mass energy of√s=3.650 GeV during May 2009 and at√s=3.773 GeV from January 2010 to May 2011.By analyzing the large angle Bhabha scattering events,the integrated luminosities of the two data sets are measured to be(44.49±0.02±0.44)pb 1and(2916.94±0.18±29.17)pb 1,respectively,where the first error is statistical and the second error is systematic.
The possibility of studying D 0-D 0 mixing at a giga-Z linear collider "Z factory" where 10 9 hadronic Z 0 decays can be accumulated is examined.We discuss the sensitivity for the measurements of neutral D mixing parameters.These results are compared to those attainable at B factories.We find that the typical decay length of the neutral D mesons at Z factory is about 10 times larger than that at B factory.In addition,the resolution of the vertex detector of a giga-Z factory is 2-3 times better than that of B factory.The proper time resolution at Z factory is about 20-30 times better than that at B factory.Therefore the determination of the mixing parameters at a giga-Z factory is more precise.
LI HaiBo 1 & YANG MaoZhi 2 1 Institute of High Energy Physics,P.O.Box 918,Beijing 100049,China
