e~+e~-湮没过程的多重数分布

本文分析了e~+e~-湮没中多重数的实验分布,指出可能是夸克数目服从四动量守恒限制下的Poisson分布,加上组合过程影响的结果.并利用一种在其他方面取得明显成功的夸克组合律作了计算,得到与实验符合的结果.还对轻夸克jet作了单独讨论.     

高能e~+e~-湮没中多粒子产生的管状袋模型

本文提出了一种研究高能e~+e~-湮没过程中多粒子产生的管状袋模型.利用袋参数β确定强子化几率密度与物质化能量的平方成正比,成功地解释了最新实验数据(TASSO,HRS)给出的近似KNO标度无关性.     

e~＋e~－湮没中L＝1激发态重子的产生比例

用一个简化模型概括的低激发态重子主要衰变分支比和我们在文献［２］中给出的基本关系，得出Ｌ＝１激发态重子对∑（１３８５），∑＋，（１５３０）和的衰变贡献，进而用γ共振能量下的实验值Ｒ１＝（１５３０），Ｒ２＝∑（１３８５）／∑和Ｒ３＝∧（１５２０）／∑（１３８５）作输入，估算了Ｌ＝１的各激发态重子的产生比例．     

ILC上e~+e~-对撞产生t~+t~-夸克对

本文结合国际直线对撞机(ILC)的实验讨论了e+e-湮灭产生t+t-对过程.在具体计算过程中,本文采用一种新的计算方式,即"混合链图传播子"修正下的反应截面,首先对QED中Dyson链图传播子理论在电弱统一标准模型(WS)中做了推广,获得WS中的光子、中间玻色子混合链图传播子,进而计算了γ,Z0混合链图修正下e+e-→t+t-反应总截面σchain,并与单圈修正下的总截面σloop和最低阶总截面σ0做了对比分析,发现在国际直线对撞机对撞能区,σchain对σloop和σ0的修正很大.此外,作者还结合国际直线对撞机的对撞亮度,讨论了每年可在ILC上产生t+t-对的事例数.     

快度近关联与e~+e~-湮没中的多重数分布

详细讨论了快度近关联的组合规则,给出了在此规则下N个夸克和N个反夸克快度随机排列时,组合成介子和重子的平均数公式及重数分布的图谱.利用普适的和模型无关的能量和平均夸克对数的关系式,计算了e~+e~-湮没中的平均介子数,平均质子数和能量的关系,计算了三个能量下的多重数分布.并且和实验及负二项分布进行了比较.     

高能e~ e~-→e~ e~- 强子过程中的电弱干涉效应

在这篇文章中,我们用[2]中的结果讨论了与极化光子结构函数相关的电弱干涉效应,这个效应提供了对G-W-s(格拉肖-温伯格-萨拉姆)模型作进一步检验的可能并且导致对光子结构函数的更深入的了解。     

高能e~+e~-→两喷注时的夸克产生律

本文利用e~+e~-→重夸克jets中,可分辨电磁激发与强作用产生的夸克的优点,对后者的产生规律作了研究,发现它产生的夸克对数满足一种简单普适规律,由此算出的、多重数分布、前后关联等等都和实验符合、本文介绍了与的比较.     

e+e－湮没过程的重子产生

本文指出(3/2)⁺与(1/2)⁺重子相对权重的改变对末态长寿命重子产额没有影响,而对(3/2)⁺重子产额改变显著.分析e⁺e^－实验资料发现对(3/2)⁺重子很强的抑制参数为0.3,由此得到的末态重子产额及产额比才能与实验符合.     

e~+e~- →charm cross sections via ISR

We discuss recent measurements of exclusive e+e-cross sections for charmed hadron final states near threshold performed by Belle and BABAR.The results are based on a study of events with initial-state-radiation photons in a large data sample collected with the Belle and BABAR detectors at the Υ(4S) resonance and nearby continuum.     

Experimental review of e~+e~-→ππh_c

We review the recent BESIII measurement of e~+e~-→ππh_c in which its line shape is studied between the center-of-mass energies of 3.9 to 4.42 Ge V and an iso-vector charmonium-like state Z_c(4020) is observed in the invariant mass of πhc at the BESIII experiment. The charged Z_c(4020)~± is the second observed Z_c state following Z_c(3900), while the Z_c(4020)~0 is the first observed neutral Z_c state. The line shape of σ(e~+e~-→ππh_c) is also reanalyzed in view of searching for the Y state and the existence of the Y(4220) state is confirmed and compared with the previous work of the BESIII experiment.     

在s~(1/2)=4.03GeV的e~+e~-湮没中D_s~+单标记的研究及D_s~+D_s~-对产生截面的测定

利用北京正负电子对撞机 (BEPC)和北京谱仪 (BES) ,基于在质心系能量s=4.0 3GeV的e+ e-湮没中 ,D+ s 单标记的分析结果 ,测定了D+ s →K 0 K+ 和D+ s →K0 K+ 衰变的分支比。其结果Br(D+ s →K 0 K+ ) =(3.0 2± 0 .94±0 .91) % ,Br(D+ s →K0 K+ ) =(3.2 8± 1.2 2± 0 .94) %与世界平均值在误差范围内一致 .用π+ ,K 0 K+ ,K0 K+ 作为单标记 ,共观测到 94± 13个D+ s 事例 ,测得在e+ e-湮没中D+ s D-s 对产生的截面为σprodD+s D-s =45 1± 6 3± 118pb .     

Z′particles and e~+ e~- → τ~+ μ~-

We analyze the cross section of e + e-→τ + μ-within the frameworks of SM and its Z extension.The theoretical prediction of the SM on the total cross section is suppressed by the tiny neutrino masses.On the other hand,the contributions from Z to the cross section are enhanced drastically because of the tree level FCNC couplings among Z and leptons.     

e~+e~-湮灭与大横动量P_⊥分布

本文从e~+c~-湮灭的次级粒子的横动量分布的表示式中,导出了当m⊥■T时横质量m⊥的平均无标度性.     

e~ e~-湮灭中的夸克组合律

本文指出,夸克组合中快度近关联与QCD的要求一致,并与慢强子先产生原则一起,完全确定夸克组合律,并自动排除重子偶素的产生.给出了N对夸克随机组成介子、重子与反重子的计算公式.把它用于e~ e~-湮灭,根本不需另引入双夸克对的真空激发等假定,即自然解释了重子的显著产生。     

Evidence for resonant structures in e~+e~-→π~+π~-h_c

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.     

PGBs对高能e~＋e~－湮没产生顶夸克对的单圈量子效应

在一代Ｔｅｃｈｎｉｃｏｌｏｒ（ＴＣ）模型中计算了ＰＧＢｓ（ＰｓｅｕｄｏＧｏｌｄｅｎｓｔｏｎｅＢｏｓｏｎｓ）对高能ｅ＋ｅ－→ｔｔ过程的单圈量子效应．给出了重整化的形状因子和矩阵元．计算了ＰＧＢｓ对总截面前后不对称参数ＡＦＢ和左右不对称参数ＡＬＲ的虚贡献，结果表明选取适当的参数值，新物理对以上可测量的贡献最大分别可达：－１２．３％、－３．３％和－１１．７％．在下一代对撞机上这一理论结果能为ＴＣ理论打开实验的窗口．同样的计算表明ＰＧＢｓ对ｅ＋ｅ－→ｂｂ过程的单圈贡献小于－１．０％．     

Study of the rare decay J/ψ→e~+e~-φ

We study the decay process of J/ψ→e~+e~-φ where the relatively clean electromagnetic(EM) transitions appear at leading order at tree level while the hadronic contributions only emerge via hadronic loop transitions. We include the low-lying scalar f_0(980) and pseudoscalar η/η as the dominant contributions in the evaluation of the hadronic loop contributions. It is found that the hadronic effects are negligible compared with the EM contributions.The decay width of J/ψ→e~+e~-φ is determined to be about 2.12 × 10~(-6) ke V if there is no other leading mechanism contributing. This result will be tested by the BESIII experiment with a large J/ψ data sample.     

干涉项对e~+e~-→q+ng两种色连接几率的影响

传统高能e+ e-→hadrons事例产生器普遍采用大Nc 近似 ,使色单态链产生几率达到 10 0 %而色分离态几率为 0 .本文在Nc=3的真实情况下 ,研究了干涉项中颜色部分和动量部分的来源及性质后发现 ,对e+ e-→qq +ng部分子末态中胶子数 2 ,3,干涉项使色单态链产生几率进一步下降到 6 7% ,5 8% ,而n =2时的色分离态几率则增大至不考虑干涉项的 2倍 .由上推断当胶子数n更大时色单态链几率将远小于 1,色分离态几率将更显著增加     

在s~(1/2)=10—178GeV的e~+e~-湮没中粲介子与美介子的产额

根据电弱统一标准模型,本文研究了e~+e~-湮没中各种味道i(i=u,d,s,c,b)的夸克喷注产生几率P_i·P_i是能量s~(1/2)的函数。计算的5种夸克喷注产生的几率之比P_u:P_d:P_s:P_c:P_b,当s~(1/2)<30 GeV时为4:1:1:4:1,当s~(1/2)=m_z=91.16 GeV时为7:9:9:7:9,而当s~(1/2)=78与117GeV时为1:1:1:1:1.利用P_c与P_b,我们计算了s~(1/2)=10-178GeV的e~+e~-湮没中粲介子与美介子的产额。     

A possible explanation of the threshold enhancement in the process e~+e~-→∧■

Inspired by the recent measurement of the process e~+e~-→∧■,we calculate the mass spectrum of the 0 meson with the GI model.For the excited vector strangeonium states ?(3 S,4 S,5 S,6 S) and ?(2 D,3 D,4 D,5 D),we investigate the electronic decay width with the Van Royen-Weisskopf formula,and the partial widths of the ∧■,■,and■ decay modes with the extended quark-pair creation model.We find that the electronic decay width of the D-wave vector strangeonium is about 3～8 times larger than of the S-wave vector strangeonium.Around 2232 Me V,the partial decay width of the ∧■ mode can be up to several MeV for ?(3~3 S_1),while the partial ∧■ decay width of ?(2~3 D_1) is O(10~(-3)) keV.If the threshold enhancement reported by the BESIII collaboration arises from the strangeonium meson,this state is very likely the ?(3~3 S_1) state.We also note that the ∧■ and∑~+■partial decay widths of the states ?(3~3 D_1) and ?(4~3 S_1) are several MeV,which is sufficient to be observed in future experiments.