分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-11-10
摘要: A detailed theoretical derivation of the cross sections of e+e− → e+e− and e+e− → µ+µ− around the J/ψ resonance is reported. The resonance and interference parts of the cross sections, related to J/ψ resonance parameters, are calculated. Higher-order corrections for vacuum polarization and initial-state radiation are consid-ered. An arbitrary upper limit of radiative correction integration is involved. Full and simplified versions of analytic formulae are given with precision at the level of 0.1% and 0.2%, respectively. Moreover, the results obtained in the paper can be applied to the case of the ψ(3686) resonance.
分类: 物理学 >> 凝聚态:结构、力学和热性能 提交时间: 2017-03-26
摘要: On the basis of the study of inclusive hadronic events, two methods are adopted to determine the number of produced ψ(2S) events collected by BES in 2001-2002 run, which is 14:0 £ 106 with the uncertainty of 4%.
分类: 物理学 >> 核物理学 提交时间: 2016-09-13
摘要: A high luminosity Circular Electron Positron Collider (CEPC) as a Higgs Factory will be helpful to the precision measurement of the Higgs mass. The signal-background interference effect is carefully studied for the Higgs diphoton decay mode in the associated Z boson production at the future e+e− colliders at energy 246GeV. The mass shifts go up from about 20MeV to 50MeV for the experimental mass resolution ranging from 0.8GeV to 2GeV.
分类: 物理学 >> 核物理学 提交时间: 2016-08-30
摘要: The Circular Electron Positron Collider (CEPC) is a future Higgs factory proposed by the Chinese high energy physics community. Using Monte Carlo samples of 5 ab−1 at 250 GeV center-of-mass energy, the benchmark luminosity of CEPC Higgs runs, model independent (MI) analyses on Higgsstrahlung (ZH) cross section σZH and Higgs mass mH are performed with ZH events where the Z boson decays into a pair of muons. The relative precision of σZH could reach 0.92\% and the mH could be measured to an accuracy of 6.5 MeV. Using information from Higgs decay final states, the backgrounds could be further reduced, leading to a mass precision of 5.4 MeV. The impacts of tracker size are investigated and parameterized for these measurements. Using similar analysis technology, we analyzed the capability of CEPC in measuring the Higgs invisible decay. Using ZH (Z→μ+μ−) events at 5 ab−1, the upper limit of invisible decay cross section beyond the standard model (SM) σBSMZH,H→inv can be determined to be 2.0 fb at 95\% confidence level.
提交时间: 2017-05-02
摘要: The electroplating pretreatment of NdFeB magnets was simulated in this study, and the effect of the pickling process on element, matrix morphology and texture was discussed. The results showed that in the ordinary circumstance the acid solution concentrat