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Comparison of dark energy models:A perspective from the latest observational data

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中国科学：物理学、力学、天文学英文版 2010年第9期53卷 1631-1645页

作者： LI Miao1,2,LI XiaoDong2,3.& ZHANG Xin1,4 1Kavli institute for theoretical physics {3.,Chinese Academy of Sciences,beijing 100190,{3. 2key laboratory of frontiers in theoretical physics,institute of theoretical physics,Chinese Academy of Sciences,beijing 100190,{3. 3.nterdisciplinary Center for theoretical Study,University of Science and Technology of {3.,Hefei 23.026,{3. 4Department of physics,College of Sciences,Northeastern University,Shenyang 110004,{3. Kavli institute for theoretical physics {3. Chinese Academy of Sciences Beijing China key laboratory of frontiers in {3. {3. Institute of Theoretical Physics Chinese Academy of Sciences Beijing China Interdisciplinary Center for theoretical Study University of Science and Technology of China Hefei China Department of physics College of Sciences Northeastern University Shenyang China

We compare some popular dark energy models under the assumption of a flat universe by using the latest observational data including the type Ia supernovae Constitution compilation,the baryon acoustic oscillation measurement from the Sloan Digital Sky Survey,the cosmic microwave background measurement given by the seven-year Wilkinson Microwave Anisotropy Probe observations and the determination of H0 from the Hubble Space *** comparison statistics such as the Bayesian and Akaike information criteria are applied to assess the worth of the *** statistics favor models that give a good fit with fewer *** on this analysis,we find that the simplest cosmological constant model that has only one free parameter is still preferred by the current *** other dynamical dark energy models,we find that some of them,such as the αdark energy,constant w,generalized Chaplygin gas,Chevalliear-Polarski-Linder parametrization,and holographic dark energy models,can provide good fits to the current data,and three of them,namely,the Ricci dark energy,agegraphic dark energy,and Dvali-Gabadadze-Porrati models,are clearly disfavored by the data.

关键词： dark energy models observational constraints model comparison information criteria

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 {3. physics china,Chinese Academy of Sciences,beijing 100190,china physics Department Zhengzhou University Zhengzhou China Kavli institute for theoretical physics {3. Chinese Academy of Sciences Beijing 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

Lepton flavor violating Z-boson decays at GigaZ as a probe of supersymmetry

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Science china(physics,Mechanics & Astronomy) 2010年第11期53卷 1949-1952页

作者： YANG JinMin 1,2 1 Department of physics,Henan Normal University,Xinxiang 453.07,china 2 institute of theoretical physics,Chinese Academy of Sciences,{3.,china Department of physics Henan Normal University Xinxiang China institute of theoretical physics Chinese Academy of Sciences Beijing China

This paper briefly reviews the lepton flavor violating Z-decays at GigaZ as a probe of supersymmetry by focusing on Z → i j in two representative supersymmetric models: the minimal supersymmetric model without R-parity and the supersymmetric seesaw *** work concludes that under the current experimental constraints from LEP and i → j γ,these rare decays can still be enhanced to reach the sensitivity of the ***,supersymmetry can be probed via these decays at GigaZ.

关键词： Z-decay GigaZ supersymmetry

Challenges in the theoretical investigations of lipid membrane configurations

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Chinese physics B 2013年第2期22卷 36-44页

作者：涂展春 Department of physics Beijing Normal University Kavli institute for theoretical physics {3. Chinese Academy of Sciences

We report some key results in the theoretical investigations of configurations of lipid membranes and present several challenges in this field,which involve（i）the exact solutions to the shape equation of lipid vesicles,（ii）the exact solutions to the governing equations of open lipid membranes,（iii）the neck condition of two-phase vesicles in the budding state,（iv） the nonlocal theory of membrane elasticity,and（v）the relationship between the symmetry and the magnitude of the free energy.

关键词： configuration lipid membrane

Constraints of f(R) gravity in Palatini approach with observational Hubble data

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Science china(physics,Mechanics & Astronomy) 2011年第8期54卷 1378-1383页

作者： ZHAI ZhongXu & LIU WenBiao Department of physics, institute of theoretical physics, beijing Normal University, beijing 100875, china Department of physics Institute of Theoretical Physics Beijing Normal University Beijing China

We use the newly released observational H(z) data (OHD), the Cosmic Microwave Background (CMB) shift parameter, and the Baryon Acoustic Oscillation (BAO) measurements data to constrain cosmological parameters of f(R) gravity in Palatini formalism in which the f(R) form is defined as f(R) = R β/Rn. Under the assumption of a spatially flat FRW universe, we get the best fitting results of the free parameters (Ωm0, n). In the calculation, we marginalize the likelihood function over H0 by integrating the probability density P ∝ e-χ2/2 to obtain the best fitting results and the confidence regions in the Ωm0-n plane. The constraints results of (Ωm0, n) = (0.3., 0.41) by OHD only and (Ωm0, n) = (0.23. 0.08) by the combination of OHD+CMB+BAO both indicate that the universe goes through three last phases, i.e., radiation dominated, matter-dominated, and late time accelerated expansion without introduction of dark energy.

关键词： f(R) gravity OHD CMB BAO accelerating expansion dark energy

Two Higgs bi-doublet left-right model with spontaneous P and CP violation

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Science china(physics,Mechanics & Astronomy) 2008年第12期51卷 1808-1825页

作者： WU YueLiang 1↑ & ZHOU YuFeng2 1 Kavli institute for theoretical physics {3., institute of theoretical physics, Chinese Academy of Sci- ences, beijing 100190, {3. 2 KEK, Tsukuba, 3.5-0801, Japan Kavli institute for theoretical physics {3. Institute of Theoretical Physics Chinese Academy of Sciences Beijing China KEK Tsukuba Japan

A left-right symmetric model with two Higgs bi-doublet is shown to be a consistent model for both spontaneous P and CP violation. The flavor changing neutral cur- rents can be suppressed by the mechanism of approximate global U(1) family symmetry. The constraints from neural K meson mass difference ΔmK are calcu- lated and it is demonstrated that a right-handed gauge boson W2 contribution in box-diagrams with mass well below 1 TeV is allowed due to a cancelation caused by a light-charged Higgs boson with a mass range of 150-3.0 GeV. The W2 con- tribution to εK can be suppressed from an appropriate choice of additional CP phases appearing in the right-handed Cabbibo-Kobayashi-Maskawa matrix. The model is also found to be fully consistent with B0 mass difference ΔmB and the mixing induced CP violation sin2βJ/ψ , which is usually difficult for the model with only one Higgs bi-doublet. The new physics beyond the standard model can be directly searched at the colliders LHC and ILC.

关键词： left-right symmetry spontaneous P and CP violation two Higgs bi-doublets new physics

Systematic study of survival probability of excited superheavy nuclei

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Science china(physics,Mechanics & Astronomy) 2011年第S1期54卷 109-113页

作者： XIA ChengJun1, SUN BaoXi1, ZHAO EnGuang2,3.& ZHOU ShanGui2,3.1College of Applied Sciences, beijing University of Technology, beijing 100124, china 2{3., Chinese Academy of Sciences, beijing 100190, china 3.enter of theoretical Nuclear physics, National laboratory of Heavy Ion Accelerator, Lanzhou 73.000, china College of Applied Sciences Beijing University of Technology Beijing China institute of theoretical physics Chinese Academy of Sciences Beijing China Center of theoretical Nuclear physics National Laboratory of Heavy Ion Accelerator Lanzhou China

The stability of excited superheavy nuclei (SHN) with 100 Z 13. against neutron emission and fission is investigated by using a statistical model. In particular, a systematic study of the survival probability against fission in the 1n-channel of these SHN is made. The present calculations consistently take the neutron separation energies and shell correction energies from the calculated results of the finite range droplet model which predicts an island of stability of SHN around Z = 115 and N = 179. It turns out that this island of stability persists for excited SHN in the sense that the calculated survival probabilities in the 1n-channel of excited SHN at the optimal excitation energy are maximized around Z = 115 and N = 179. This indicates that the survival probability in the 1n-channel is mainly determined by the nuclear shell effects.

关键词： survival probability superheavy elements island of stability neutron emission fission

Half-lives and fine structure for the α decay of deformed even-even nuclei

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Science china(physics,Mechanics & Astronomy) 2011年第S1期54卷 24-31页

作者： NI DongDong1,2 & REN ZhongZhou1,2,3.1Department of physics, Nanjing University, Nanjing 210093. china 2Kavli institute for {3. physics china, beijing 100190, china 3.enter of {3. Nuclear physics, National laboratory of Heavy-Ion Accelerator, Lanzhou 73.000, china Department of physics Nanjing University Nanjing China Kavli institute for theoretical physics {3. Beijing China Center of theoretical Nuclear physics National Laboratory of Heavy-Ion Accelerator Lanzhou China

The α-decay properties of well-deformed even-even nuclei are systematically calculated within the multichannel cluster model (MCCM). Instead of working in the WKB framework, the quasibound solution to the coupled Schro¨dinger equation is presented with outgoing wave boundary conditions, and the coupling potential is taken into full account in terms of the general quantum theories. The calculated α-decay half-lives are found to agree well with the experimental data with a mean factor of less than 2. The fine structure observed in α decay is also well reproduced by the four-channel microscopic calculation. Very strikingly, the MCCM can give relatively precise descriptions of the branching ratio to excited 4+ states, which is often overestimated in the usual WKB calculations. We expect it to be a significant development of theoretical models toward quantitative descriptions of α transitions to high-spin daughter states.

关键词： α decay half-lives cluster model coupled channel approach

Collision dynamics of He@C_(60)+He@C_(60) at low energies

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Science china(physics,Mechanics & Astronomy) 2008年第7期51卷 765-772页

作者： ZHAO Qiang1,2, ZHANG FengShou1,2,3.& ZHOU HongYu1,2 1 key laboratory of Beam Technology and Material Modification of Ministry of Education, institute of Low Energy Nuclear {3., {3. Normal University, {3. 100875, china 2 {3. Radiation Center, {3. 100875, china 3.Center of theoretical Nuclear {3., National laboratory of Heavy Ion Accelerator of Lanzhou, Lanzhou 73.000, china key laboratory of Beam Technology and Material Modification of Ministry of Education Institute of Low Energy Nuclear Physics Beijing Normal University Beijing China beijing Radiation Center Beijing China Center of theoretical Nuclear physics National Laboratory of Heavy Ion Accelerator of Lanzhou Lanzhou China

A semi-empirical molecular dynamics model is developed. The central collisions of C60+C60 and He@C60+He@C60 at different incident energies are investigated based on this model. It is found that the dimer structures have been produced at proper incident energies and these fullerene dimers could be formed by a self-assembly of C60 fullerene and He@C60. The He atom has a significant effect at higher incident energy and this embedded He atom can enhance the stability of the dimer structure.

关键词： C60 He@C60 collision molecular dynamics