共查询到20条相似文献,搜索用时 31 毫秒
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BES Collaboration 《中国物理C(英文版)》1997,21(2):97-103
Using the BES data collected at √S=4.03GeV.the QED processes of e+e-→e+e-,μ+μ- have been studied. Our measurements agree with the QED prediction,and luminosities obtained from these two final states are compatible at a level of 4%.The total integrated luminosity of 23.1pb-1 was given for all data collected at this energy region from the calculation. 相似文献
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In this paper we examine the electroweak interference effects related to the polarized photon structure functions making use of the results of the ref.[2]. The effects provide the probability of a further test of the G-W-S model and may lead to a deep understanding to the photon structure functions. 相似文献
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BES Collaboration 《中国物理C(英文版)》2002,26(11):1093-1102
We report the results of a search for the semileptonic decays D+→e+ν,D+→K-π+e+ν,D0→K-e+ν and D0→K-μ+ν using the BES detector at the BEPC e+e- Collider. Using a data sample of 22.3pb-1 collected at the center of mass energy s=4.03GeV, we select 2472±87D 0 tag DX and 7628±149D 0 tag DX singly tagged D events, where the X could be γ, π 0 and/or π±. Based on the method of "combined D+and D0 single and double tags", we determine that 2471±218 D+X and 7629±251 D0 X are contained in the recoil side of the singly tagged neutral and charged D mesons, respectively. No events for the 4 semileptonic decay modes are observed in the recoil side of the tagged D mesons. The 90% confidence level upper limits of B(D+→e+ν)<1.38%,B(D+→K-π+e+ν)<2.01%,B(D0→K-e+ν)<0.53% and B(D0→K-μ+ν)<0.53% are determined from the search for the semileptonic decays of D+ and D0. 相似文献
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In the structure function approach,we calculate the threshold behaviours for e++e-→τ++τ-,which including QED radiative corrections from initial correction,vacuum polarization effect,Coulomb effect and final state correction.This theoretical prediction for threshold behaviours of τ-pair production is useful for BES new measurement of lepton τ mass. 相似文献
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The probability of Color Rearrangement at partonic level in e+e-→W+W-→h,s process is studied using the Color Effective Hamiltonian. The comparison between our results and those of Gutafson and Sjostrand et al. is also given. It is found that this probability cannot be neglected, and it is pointed out that to investigate the Color Rearrangements, the hadronization models should be developped and improved. 相似文献
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E. P. Solodov 《中国物理 C》2010,34(6):660-668
Experimental data from the PEP-II B-factory at 10.6 GeV center-of-mass (c.m.) energy, obtained via initial-state radiation (ISR) with the BABAR detector, are presented. The cross sections for many hadronic processes have been measured from the production threshold to 4-5 GeV of the e^+e^- c.m. energy. The obtained data allow to study a number of intermediate states and determine the parameters of known resonances and their branching fractions. The exclusive cross section for some number of hadronic sub-processes are presented. 相似文献
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FENG XiChen GUO YingXiang ZHOU XiaoHong LEI XiangGuo HUANG WenXue HE JianJun ZHU ShaoFei LIU Zhong ZHANG YuHu LUO YiXiao WEN ShuXian YUAN GuanJun WU XiaoGua 《中国物理C(英文版)》2000,24(4):359-363
The high-spin states of 206At have been studied in the 197An (12C, 3n)206At reaction at 12C energies from 60 to 80 MeV using technique of in-beam γ-ray spectroscopy. Measurements of Tray excitation functions, γ-γ-t coincidences, and y-ray angular distributions were performed. A level scheme for 206At, including a 10- isomer with a measured half-life of 908±400 ns, was established for the first the. The characteristics of the 10- isomers in doubly edd 206At nuclei were stressed. 相似文献
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WU Xiang-Yao LIU Xiao-Jing GONG Pi-Feng LI Qi-Lang SHI Zong-Hua GUO Yi-Qing 《中国物理C(英文版)》2006,30(11):1048-1052
In this paper, the D0→π-l+νl decay process is studied by applying light-cone QCD sum rules. The form factor of D→π transition is calculated by choosing a correlation function with a chiral current to eliminate the effect caused by the uncertainty of the twist-3 function of the pion. Therefore the calculated result of the form factor is improved, and the branching ratio of the D0→π-l+νl decay process is consistent with the new experimental data. 相似文献
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We present a preliminary measurement of the B(Ds→μνμ) with the Belle 相似文献
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We analyze the decay amplitudes of the process a2(1320)→π+π+π- using the tensor analysis method and show how to obtain three body amplitudes. 相似文献
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B. Golob 《中国物理C(英文版)》2008,32(6):495-498
We present a preliminary measurement of the B(Ds→μνμ) with the Belle
experiment at the KEKB collider. We select Ds→μνμ decays with a method that provides a high-purity of the selected sample and an absolute measurement of the branching fraction. The results are based on a data sample of 550fb-1 and are compared to similar measurements by other experiments as well as to the predictions of LQCD. We conclude with short prospects for improvements in the accuracy of the measurement.
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In order to convenience for the data analysis of BES some new relations which can be used to search for the 1-+ exotic state in J/ψ→ωX,X→KKπ have been obtained.How to search for the 1-+ exotic state in the three-step two-body hadronic decay process J/ψ→ωX,X→KK*,K*→Kπ is also discussed. 相似文献
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BES Collaboration 《中国物理C(英文版)》2002,26(1):8-16
The decay mode of J/ψ→π03(π+π-) was studied very little before. There are no informations except branching ratios for this channel in PDG book which based on less than 0.2×106J/ψ events of MARKⅠ. Now, BESⅠ has a data sample of 7.8×106J/ψ events, we can make more accurate results than MARKⅠ. Total of 3290±43 J/ψ→π03(π+π-) events including 1275±86 J/ψ→ω2(π+π-) events are selected. J/ψ→π03(π+π-) and J/ψ→ω2(π+π-) events have been generated with MC simulition for calculating events selection efficiency. BESⅠ result is: Br(J/ψ→π03(π+π-))=(2.52±0.06±0.43)% and Br(J/ψ→π03(π+π-))=(1.31±0.09±0.21)%. Meanwhile, we studied the invariant mass of 4π and ωππ to find interesting signals. It seems that there is a peak at about 1.74GeV in the invarianat mass spectrum of 4π, and a enhancement was also found at about 1.9GeV in the invariant mass spectrum of ωππ. It is not clear whether they are from resonances or background. Therefore, more work in detail is still going on. 相似文献
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滑伟 周小红 张玉虎 郭应祥 Oshima M. Toh Y. Koizumi M. Osa A. Hatsukawa Y. 亓斌 张双全 孟杰 Sugawara M. 《中国物理 C》2009,33(9):743-747
High-spin levels of ^189Pt have been studied with the in-beam T-spectroscopy method via the ^176Yb(^18O,5n) reaction at the beam energies of 88 and 95 MeV. The previously known "vi-1 13/2 band has been confirmed, and its unfavored signature branch extended up to the 31/2^+ state. Within the framework of the triaxial particle-rotor model, the vi-1 13/2 band is suggested to be associated with the 11/2[615] configuration, and to have triaxial deformation. 相似文献
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In this paper an important character was found that the final hadron multiplicities of direct J/ψ decays satisfy the same universal mass dependence as that in e+e-→q0q0 continuum events. This indicates that the fragmentation of quark and gluon to hadron follows the same mechanism. We give a reasonable interpretation to final baryon multiplicity that is enhanced by 2.5 times in direct Y decays compared to the continuum through our calculating results. But we cannot find this similar phenomenon in direct J/ψ decays. 相似文献
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A study of the dynamical fluctuation properties at various c.m. energies in e+e- collisions is performed using the Monte Carlo method. The results suggest that, after the normalized factorial moments of 3-dimensional phase space are analyzed using an isotropical phase space partition, the NFM describing non-linear dynamical properties show a power-law scaling, i.e., the dynamical fluctuations in higher dimensional phase space are isotropic. For c.m. energies √s≤80 GeV, the scaling exponents φq increase rapidly with the c.m. energy and for c.m. energies √s>80GeV, the φq gradually saturate. 相似文献
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本文提出一个证认宇宙线中新X粒子的分析原则:筛比较法。对目前全部已知乳胶室事例进行了判定。其中结果有D介子和∑c+重子的平均寿命和质量,τ(D&;#177;)=5.8×10-13秒,τ(D0)=2.0×10-13秒,τ(∑c+)(?)2.4×10-14秒。支持△I=1的选择规则。 相似文献
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Following perturbative QCD theory, the two-jet and three-jet angular distributions in polarized e+e- annihilation is computed using the dimensional regularization scheme. The azimuthal inhomogeneity caused by the polarization is discussed. We also compute the exact formulae of dependence on ε´,δ to the second order and discuss the correction to G.Sterman and S.Weinberg's result. 相似文献