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The lepton flavor violating signal of the extra gauge boson Z′in photon-photon collision at the ILC

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Science china(physics,Mechanics & Astronomy) 2010年第11期53卷 1992-1997页

作者： LIU GuoLi 1,2 1 physics Department,Zhengzhou University,Zhengzhou 450001,china 2 Kavli Institute for Theoretical physics china,Chinese Academy of Sciences,Beijing 100190,china 1. physics Department Zhengzhou University Zhengzhou 450001 China2. Kavli Institute for Theoretical Physics China Chinese Academy of Sciences Beijing 100190 China

The hitherto unconstrained lepton flavor mixings,induced by the new gauge boson Z ,which are the prediction of many new physics models,such as topcolor-assisted technicolor (TC2) models and flavor-universal TC2 models,may lead to the lepton flavor violating productions of τμˉ,τeˉ and μeˉ in photon-photon collision at the proposed International Linear Collider (ILC).Through a comparative analysis of these processes,we find that the better channel to probe the new physics models is the production of τμˉ or τeˉ which occurs at a much higher rate than μeˉ production due to the large mixing angle and the large flavor changing coupling,and may reach the detectable level of the ILC for a large part of the parameter *** the rates predicted by the Standard Model are far below the detectable level,these processes may serve as a sensitive probe for such new physics models.

关键词： new gauge boson Z lepton flavor violating processes photon-photon

Free Volume Changes in γ-Irradiated Polyethylene and Polytetraflourethylene

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Journal of Materials Science & Technology 2000年第3期16卷 302-304页

作者： Xianyi ZHOU (Dept. of Modern physics, University of Science and Technology of china, Hefei 230027, china) Linhua ZHAI (Department of physics, Anhui Normal University, Wuhu 241000, china) Jiangfeng DU and Rongdian HAN (Department of Modern physics, Univers Department of Modern physics University of Science and Technology of China Hefei 230027 China Department of physics Anhui Normal University Wuhu 241000 China

Positron lifetime spectrum was measured and the change of the free volume was studied for commercial polyethylene (PE) and polytetrafluoroethylene (PTFE) during 7-irradiation processing up to 265 kGy. The free volume size increases but the crystallinity decreases as irradiation dose increases in PE. Both qualities (free volume size and crystallinity) in PTFE display an opposite behavior. The fractional free volume reduces monotonically with increasing irradiation dose in both PE and PTFE. The competition between the crosslinkmg and the splitting decomposition in polymers can be used to understand the free volume changes with irradiation dose.

关键词： PTFE Irradiated Polyethylene and Polytetraflourethylene

Constraints on smoothness parameter and dark energy using observational H(z) data

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Research in Astronomy and Astrophysics 2011年第2期11卷 125-136页

作者： Hao-Ran Yu1,Tian Lan1,Hao-Yi Wan2,Tong-Jie Zhang1,3 and Bao-Quan Wang4 1 Department of Astronomy,Beijing Normal University,Beijing 100875,china 2 Business Office,Beijing Planetarium,Beijing 100044,china 3 Center for High Energy physics,Peking University,Beijing 100871,china 4 Department of physics,Dezhou University,Dezhou 253023,china Department of Astronomy Beijing Normal University Beijing 100875 China Business Office Beijing Planetarium Beijing 100044 China Center for High Energy physics Peking University Beijing 100871 China Department of physics Dezhou University Dezhou 253023 China

With large-scale homogeneity,the universe is locally inhomogeneous,clustering into stars,galaxies and larger *** property is described by the smoothness parameter α which is defined as the proportion of matter in the form of intergalactic *** we consider the inhomogeneities over a small scale,there should be modifications of the cosmological distances compared to a homogenous *** and Roeder developed a second-order ordinary differential equation（D-R equation） that describes the angular diameter distance-redshift relation for inhomogeneous cosmological ***,we may obtain the D-R equation for observational H（z） data（OHD）.The density-parameter ΩM,the state of dark energy ω,and the smoothness-parameter α are constrained by a set of OHD in a spatially flat XCDM universe as well as a spatially flat XCDM *** using a χ2 minimization method,we get α = 0.81＋0.19-0.20 and ΩM = 0.32＋0.12.0.06 at the 1σ confidence *** we assume a Gaussian prior of ΩM = 0.26 ± 0.1,we get α = 0.93＋0.07-0.19 and ΩM = 0.31＋*** the XCDM model,α is constrained to α≥ 0.80 but ω is weakly constrained around-1,where ω describes the equation of state of the dark energy（pX = ωρX）.We conclude that OHD constrains the smoothness parameter more effectively than the data of SNe Ia and compact radio sources.

关键词： cosmology -- dark energy -- cosmological parameters

Spontaneous chiral-symmetry breaking of lattice QCD with massless dynamical quarks

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Science china(physics,Mechanics & Astronomy) 2007年第1期50卷 6-14页

作者： LUO XiangQian Department of physics,School of physics and Engineering,Sun Yat-Sen University,Guangzhou 510275,china 1. Department of physics School of Physics and Engineering Sun Yat-Sen University Guangzhou 510275 China

One of the most challenging issues in QCD is the investigation of spontaneous chiral-symmetry breaking, which is characterized by the non-vanishing chiral condensate when the bare fermion mass is zero. In standard methods of the lattice gauge theory, one has to perform expensive simulations at multiple bare quark masses, and employ some modeled functions to extrapolate the data to the chiral limit. This paper applies the probability distribution function method to computing the chiral condensate in lattice QCD with massless dynamical quarks, without any ambiguous mass extrapolation. The results for staggered quarks indicate that this might be a promising and efficient method for investigating the spontaneous chiral-symmetry breaking in lattice QCD, which deserves further investigation.

关键词： lattice QCD spontaneous chiral-symmetry breaking dynamical quarks

LONG TIME ASYMPTOTIC BEHAVIOR OF SOLUTION OF DIFFERENCE SCHEME FOR A SEMILINEAR PARABOLIC EQUATION (Ⅱ)

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Journal of Computational Mathematics 1998年第5期16卷 571-576页

作者： Hui Feng(Shenzhen University Normal College, Shenzhen 518060, china Laboratorp of Computational physics, Institute of Applied physics and Computational Mathematics,P.O.Box 8009, Beijing 100088, china )Long-jnn Shen(Laboratory of Computational physics, In Shenzhen Univ Wormal Coll Shenzhen 518060 Peoples R China Inst Appl Phys & Computat Math Lab Computat Phys Beijing 100088 Peoples R China

In this paper we prove the solution of explicit difference scheme for a semilinear parabolic equation converges to the solution of difference scheme for the relevant nonlinear stationary problem as t→∞. For nonlinear parabolic problem, we obtain the long time asymptotic behavior of its discrete solution which is analogous to that of its continuous solution. For simplicity, we discuss one-dimensional problem.

关键词： Asymptotic behavior Explicit difference scheme Semilinear parabolic equation.

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Theory study of shapes in ^(187,189)Tl nuclei

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Science china(physics,Mechanics & Astronomy) 2009年第6期52卷 818-821页

作者： LIU YanXin1, YU ShaoYing1,2,3, SHEN CaiWan1,5 & DONG YongSheng1,2,4 1 School of Science, Huzhou Teachers College, Huzhou 313000, china 2 School of Science and Information Engineering, Zhejiang Normal University, Jinhua 321000, china 3 Institute of Theoretical physics, Chinese Academy of Sciences, Beijing 100080, china 4 Department of physics, Jining Teachers College, Jining 012.00, china 5 Center of Theoretical Nuclear physics, National Laboratory of Heavy Ion Accelerator of Lanzhou, Lanzhou 730000, china School of Science Huzhou Teachers College Huzhou 313000 China School of Science and Information Engineering Zhejiang Normal University Jinhua 321000 China Institute of Theoretical physics Chinese Academy of Sciences Beijing 100080 China Department of physics Jining Teachers College Jining 012000 China Center of Theoretical Nuclear physics National Laboratory of Heavy Ion Accelerator of Lanzhou Lanzhou 730000 China

The nuclear shapes of 187,189Tl were investigated theoretically in this work. The total routhian surface (TRS) calculations were performed for N=106 and 108 isotopes of thallium (Z=81). The single-particle energies were obtained from the deformed Woods-Saxon potential, with the Lipkin-Nogami (LN) treatment of pairing. It is found that the collective oblate rotation coexists with the high-K prolate rotation. Superdeformed prolate rotation is included in this calculation.

关键词： nuclear shape oblate rotation prolate rotation

Electromagnetic retarded interaction and symmetry violation of time reversal in high order stimulated radiation and absorption processes of light

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Science china(physics,Mechanics & Astronomy) 2008年第3期51卷 282-298页

作者： MEI XiaoChun Department of physics,Fuzhou University,Fuzhou 350025,china 1. Department of physics Fuzhou University Fuzhou 350025 China

It has been proved that when the retarded effect (or multiple moment effect) of radiation fields is taken into account,the high order stimulated radiation and stimulated absorption probabilities of light are not the same so that time reversal symmetry would be violated,though the Hamiltonian of electromagnetic interaction is still unchanged under time reversal. The reason to cause time reversal symmetry violation is that certain filial or partial transition processes of bound atoms are forbidden or cannot be achieved due to the law of energy conservation and the special states of atoms themselves. These restrictions would cause the symmetry violation of time reversal of other filial or partial transition processes which can be actualized really. The symmetry violation is also relative to the asymmetry of initial states of bound atoms before and after time reversal. For the electromagnetic interaction between non-bound atoms and radiation field,there is no such kind of symmetry violation of time reversal. In this way,the current formula on the parameters of stimulated radiation and absorption of light with time reversal sym-metry should be revised. A more reliable foundation can be established for the theories of laser and nonlinear optics in which non-equilibrium processes are in-volved.

关键词： quantum mechanics stimulated radiation and absorption of light retarded interaction time reversal symmetry violation laser nonlinear optics non-equilibrium processes

Principle of limitation of physical quantities and cyclic universe

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Science china(physics,Mechanics & Astronomy) 2008年第5期51卷 451-458页

作者： HE GuoZhu Department of physics,Nankai University,Tianjin 300071,china 1. Department of physics Nankai University Tianjin 300071 China

A close study of Heisenberg uncertainty principles reveals many significant facts,and all four major physical quantities,energy,time,momentum and length,have both lower and upper ***,many questions come *** are these limits?Some answers may lead to the understanding of the development of our *** is the shortest limit of time?At the beginning of big bang,there exists a tre-mendously short time,the Planck *** may be just the shortest time limit in our *** longest time limit might be the lifetime of our *** longest length might be the final diameter of our expanding *** these lead to a finite *** more coupling formulae are formed for the other two pairs of physical quantities,mass and speed,thermal energy and *** four physical quantities must also have *** already knew that speed has upper limit and temperature has lower *** these two formulae,Planck and Einstein equations are derived *** most other physical quantities are somewhat related to these major physical quantities,it seems that there exists a principle of limitation of physical quantities.A quantitative sketch of big bang is *** also shows that our universe will contract back to another big *** principle of limitation opens up some fields of *** may bring nature back to the harmony and determined world described by classical physics.

关键词： principle of limitation of physical quantities limits coupling formulae cyclic universe extension of conven-tional quantum mechanics no uncertainty for physical quantities quantitative evaluation of big bang

Single-molecule studies of DNA by molecular combing

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Progress in Natural Science:Materials International 2007年第5期17卷 493-499页

作者： Liu Yuying, Wang Pengye and Dou Shuoxing (College of Science, china Agricultural University, Beijing 100083, china Laboratory of Soft Matter physics, Beijing National Laboratory for Condensed Matter physics, Institute of physics, Chinese Academy of Sciences, Beijing 100080, china) [a]College of Science China Agricultural University Beijing China [b]Laboratory of Soft Matter physics Beijing National Laboratory for Condensed Matter PhysicsInstitute of Physics Chinese Academy of Sciences Beijing China

Molecular combing is a powerful method for aligning a large array of DMA molecules onto a surface. It is a process whereby DNA molecules are stretched and aligned on a glass surface by the force via fluid flow. The ability to comb up to several hundred DNAs on a single cover slip allows for a statistically significant number of measurements to be made. These features make molecular combing an attractive tool for genomic studies, such as DNA replication, DNA transcription, DNA-protein interaction and so on. In this review article, we discuss the molecular combing principle, method and its applications.

关键词： DNA molecule molecular combing DNA-protein interaction.