In this paper,I review recent progress in the study of the XYZ particles at Belle.I only focus on studies with charmonium and one or more light mesons in the final states.This covers the X(3872),X(3915),Y(4140),X(4350),and the charged Z states.
The cross sections of e+e-→π+π-hc at center-of-mass energies from 3.90 to 4.42 GeV were measured by the BES and the CLEO-c experiments. Resonant structures are evident in the e+e-→π+π-hc line shape. The fit to the line shape results in a narrow structure at a mass of(4216±18) MeV/c2and a width of(39±32) MeV, and a possible wide structure of mass(4293±9) MeV/c2and width(222±67) MeV. Here, the errors are combined statistical and systematic errors. This may indicate that the Y(4260) state observed in e+e-→π+π-J/ψ has a fine structure in it.
The beam energy measurement system is of great importance for both BEPC-Ⅱ accelerator and BES-III detector. The system is based on measuring the energies of Compton back-scattered photons. In order to meet the requirements of data taking and improve the measurement accuracy, the system has continued to be upgraded, which involves the updating of laser and optics subsystems, replacement of a view-port of the laser to the vacuum insertion subsystem, the use of an electric cooling system for a high purity germanium detector, and improvement of the data acquisition and processing subsystem. The upgrade system guarantees the smooth and efficient measurement of beam energy at BEPC-II and enables accurate offline energy values for further physics analysis at BES-Ⅲ.
To achieve a high precision τ mass measurement at the high luminosity experiment BESIII,Monte Carlo simulation and sampling technique are utilized to simulate various data taking cases for single and multiparameter fits by virtue of which the optimal scheme is determined. The optimized proportion of luminosity distributed at selected points and the relation between precision and luminosity are obtained. In addition,the optimization of the fit scheme is confirmed by scrutinizing a variety of fit possibilities.
The beam energy measurement system at BEPCII is composed of there parts:laser source and optics system,laser-electron interaction system and High Purity Germanium(HPGe) detector system.The special components and construction of each part are introduced,especially about radiation background measurement in the storage ring,which is of great importance for the safe commissioning of HPGe detector.
The kinematic properties of two-body decay near τ threshold are studied according to the special capacity of the BEPC accelerator and the BESⅢ detector.Explicitly presented are the transformations of energy and momentum of hadronic particles between different reference frames,and the corresponding distributions.A brand new method is proposed to obtain the energy spread of the accelerator by fitting the energy distribution of hadron from τ semi-leptonic decays.
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 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
