A photon conversion finder （PCF） based on track information from the main drift chamber （MDC） of the Beijing Spectrometer （BESⅢ） at the Beijing Electron Positron Collider （BEPCⅡ） is developed. The validation of the PCF is done by reconstructing π 0 and measuring the branching fraction of J/ψ→γη . Using the developed PCF tool, we mapped the materials from the interaction point through the BEPCII beam pipe up to the inner wall of the MDC.
Using data samples collected at center-of-mass energies of √s=4.009, 4.230, 4.260, and 4.360 GeV with the BES0 detector operating at the BEPC/ collider, we perform a search for the process e＋e-→γχc,j （J =0, 1, 2） and find evidence for e＋e-→γχc1 and e＋e-→γχc2 with statistical significances of 3.0σ and 3.4σ, respectively. The Born cross sections σB（e＋e-→γχc,j）, as well as their upper limits at the 90% con dence level （C.L.） are determined at each center-of-mass energy.
The numbers of ψ（3686） events accumulated by the BESⅢ detector for the data taken during 2009 and 2012 are determined to be（107.0±0.8）×10^6 and（341.1±2.1）×10^6, respectively, by counting inclusive hadronic events,where the uncertainties are systematic and the statistical uncertainties are negligible. The number of events for the sample taken in 2009 is consistent with that of the previous measurement. The total number of ψ（3686） events for the two data taking periods is（448.1±2.9）×10^6.
We propose to understand the mixing angles and CP-violating phases from the A（48） family symmetry combined with the generalized CP symmetry. A model-independent analysis is performed by scanning all the possible symmetry breaking chains. We find a new mixing pattern with only one free parameter, excellent agreement with the observed mixing angles can be achieved and all the CP-violating phases are predicted to take nontrivial values. This mixing pattern is testable in the near future neutrino oscillation and neutrinoless double-beta decay experiments. Finally, a flavor model is constructed to realize this mixing pattern.
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
By analyzing 2.93 fb-1 data collected at the center-of-mass energy v/S = 3.773 GeV with the BESIII detector, we measure the absolute branching fraction of the semileptonic decay D＋- k0e＋ ve via k0-π0π0 - （8.59 ± 0.14 ± 0.21）% using k0- k0-π0π0, where the first uncertainty is statistical and the second systematic. Our result is consistent with previous measurements within uncertainties..
Data sets were collected with the BESⅢ detector at the BEPCⅡ 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-1 and （2916.94±0.18±29.17） pb-1, respectively, where the first error is statistical and the second error is systematic.
From December 2011 to May 2014, about 5 fb^-1 of data were taken with the BESIII detector at center-of- mass energies between 3.810 GeV and 4.600 GeV to study the charmonium-like states and higher excited charmonium states. The time-integrated luminosity of the collected data sample is measured to a precision of 1% by analyzing events produced by the large-angle Bhabha scattering process.
A measurement of the number of J/ψ events collected with the BESⅢ detector in 2009 and 2012 is performed using inclusive decays of the J/ψ. The number of J/ψ events taken in 2009 is recalculated to be（223.7±1.4）×10^6, which is in good agreement with the previous measurement, but with significantly improved precision due to improvements in the BESⅢ software. The number of J/ψ events taken in 2012 is determined to be（1086.9±6.0）×10^6. In total, the number of J/ψ events collected with the BESⅢ detector is measured to be（1310.6±7.0）×10^6, where the uncertainty is dominated by systematic effects and the statistical uncertainty is negligible.
By analyzing the large-angle Bhabha scattering events e^＋e^- → （γ）e^＋e^- and diphoton events e^＋^e- → （γ）γγ for the data sets collected at center-of-mass （c.m.） energies between 2.2324 and 4.5900 GeV （131 energy points in total） with the upgraded Beijing Spectrometer （BESIII） at the Beijing Electron-Positron Collider （BEPCII）, the integrated luminosities have been measured at the different c.m. energies, individually. The results are important inputs for the R value and J/ψ resonance parameter measurements.
