The top-pair production in association with a Z^0-boson at a photon-photon collider is an important process in probing the coupling between top-quarks and vector boson and discovering the signature of possible new phy...The top-pair production in association with a Z^0-boson at a photon-photon collider is an important process in probing the coupling between top-quarks and vector boson and discovering the signature of possible new physics. We describe the impact of the complete supersymmetric QCD （SQCD） next-to-leading order （NLO） radiative corrections on this process at a polarized or unpolarized photon collider, and make a comparison between the effects of the SQCD and the standard model （SM） QCD. We investigate the dependence of the lowest-order （LO） and QCD NLO corrected cross sections in both the SM and minimal supersymmetric standard model （MSSM） on colliding energy √s in different polarized photon collision modes. The LO, SM NLO, and SQCD NLO corrected distributions of the invariant mass of tt^--pair and the transverse momenta of final Z^0-boson are presented. Our numerical results show that the pure SQCD effects in γγ →tt^- Z^0 process can be more significant in the ＋＋ polarized photon collision mode than in other collision modes, and the relative SQCD radiative correction in unpolarized photon collision mode varies from 32.09% to -1.89% when √s goes up from 500 GeV to 1.5 TeV.展开更多
The unparticle effects on tt^- production at the future photon collider are investigated. Distributions of tt^- invariant mass and that for transverse momentum of top quark with respect to Standard Model and unparticl...The unparticle effects on tt^- production at the future photon collider are investigated. Distributions of tt^- invariant mass and that for transverse momentum of top quark with respect to Standard Model and unparticle production are predicted. An odd valley with scalar unparticle contribution appears for some values of du, which is due to the big cancellation between the contribution from SM and that from unparticle. This character may be used to study the properties of scalar unparticle. Our investigations also show that scalar unparticle may play a significant role in tt^- production at the photon collider if it exists.展开更多
对双重重子产生机制的研究有助于更好地研究微扰和非微扰QCD理论。对γγ对撞机上双重重子Ξbb的产生做了进一步研究,考虑了bb处于色三重态和色六重态的共同贡献。结果发现：质心系能量在91-1 000 Ge V变动时,Ξbb的产生率会随着质心系...对双重重子产生机制的研究有助于更好地研究微扰和非微扰QCD理论。对γγ对撞机上双重重子Ξbb的产生做了进一步研究,考虑了bb处于色三重态和色六重态的共同贡献。结果发现：质心系能量在91-1 000 Ge V变动时,Ξbb的产生率会随着质心系能量的提高而降低。但是由于积分亮度的不同,不同对撞能量下Ξbb产生的事例数大致相同。选择合适初态粒子束的极化度能有效提高Ξbb的产生率,在某些能量对撞点,初始态粒子束的极化度可以将Ξbb的产生率提高17%左右。展开更多
基金Supported in part by the National Natural Science Foundation of China under Grant Nos.10575094 and 10875112the National Science Fund for Fostering Talents in Basic Science under Grant No.J0630319+1 种基金Specialized Research Fund for the Doctoral Program of Higher Education (SRFDP) under Grant No.20050358063a Special Fund Sponsored by Chinese Academy of Sciences
文摘The top-pair production in association with a Z^0-boson at a photon-photon collider is an important process in probing the coupling between top-quarks and vector boson and discovering the signature of possible new physics. We describe the impact of the complete supersymmetric QCD （SQCD） next-to-leading order （NLO） radiative corrections on this process at a polarized or unpolarized photon collider, and make a comparison between the effects of the SQCD and the standard model （SM） QCD. We investigate the dependence of the lowest-order （LO） and QCD NLO corrected cross sections in both the SM and minimal supersymmetric standard model （MSSM） on colliding energy √s in different polarized photon collision modes. The LO, SM NLO, and SQCD NLO corrected distributions of the invariant mass of tt^--pair and the transverse momenta of final Z^0-boson are presented. Our numerical results show that the pure SQCD effects in γγ →tt^- Z^0 process can be more significant in the ＋＋ polarized photon collision mode than in other collision modes, and the relative SQCD radiative correction in unpolarized photon collision mode varies from 32.09% to -1.89% when √s goes up from 500 GeV to 1.5 TeV.
文摘讨论关于在ILC用gamma gamma到Z过程检验非对易时空能标(原文发在hep-ph/0604115).在通常时空量子场论中,由杨氏定理可知一个自旋为1的粒子不可能衰变为两个光子.但在非对易时空中此过程是允许的.因此这个过程能作为检验非对易时空的工具.ILC的光子对撞模式能实现这个过程.如果总亮度能达到500fb^(-1),我们证明对Gamma(z to gamma gamma)宽度的测量精度将比现有限制(<5.2×10^(-5)GeV)好3—4个数量级.对非对易时空能标的检测可高达几个TeV.
基金supported in part by National Natural Science Foundation of China, NCETHuo Ying-Dong Foundation
文摘The unparticle effects on tt^- production at the future photon collider are investigated. Distributions of tt^- invariant mass and that for transverse momentum of top quark with respect to Standard Model and unparticle production are predicted. An odd valley with scalar unparticle contribution appears for some values of du, which is due to the big cancellation between the contribution from SM and that from unparticle. This character may be used to study the properties of scalar unparticle. Our investigations also show that scalar unparticle may play a significant role in tt^- production at the photon collider if it exists.
文摘对双重重子产生机制的研究有助于更好地研究微扰和非微扰QCD理论。对γγ对撞机上双重重子Ξbb的产生做了进一步研究,考虑了bb处于色三重态和色六重态的共同贡献。结果发现：质心系能量在91-1 000 Ge V变动时,Ξbb的产生率会随着质心系能量的提高而降低。但是由于积分亮度的不同,不同对撞能量下Ξbb产生的事例数大致相同。选择合适初态粒子束的极化度能有效提高Ξbb的产生率,在某些能量对撞点,初始态粒子束的极化度可以将Ξbb的产生率提高17%左右。
