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Lookback time as a test for f(R) gravity in the Palatini approach

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Research in Astronomy and Astrophysics 2011年第11期11卷 1257-1265页

作者： Zhong-Xu Zhai and Wen-Biao Liu Department of physics,{1. of theoretical physics, Beijing normal university, Beijing 1.0875, China Department of physics Institute of Theoretical Physics Beijing Normal University Beijing 100875 China

We use the recently released data of lookback time (LT)-redshift relation, the cosmic microwave background shift parameter and the baryon acoustic oscillation measurements to constrain cosmological parameters of f (R) gravity in the Palatini formalism by considering the f (R) form of type (a) f (R) = R β/Rn and (b) f (R) = R + α ln R β. Under the assumption of a Friedmann-Robertson-Walker universe, we achieved the best fitting results of the free parameters (Ωm0, n) for (a) and (Ωm0, α) for (b). We find that current LT data can provide interesting and effective constraints on gravity models. Compared with other data, the LT constraints favor a smaller value of the non-relativistic matter energy density.

关键词： cosmology cosmic microwave background

Non-universal Gauge Bosons Z'and the Process e~+e~- →f

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Communications in theoretical{1. 2004年第3期41卷 419-424页

作者： YUE Chong-Xing~1.WANG Shun-Zhi~2 1.Department of physics,Liaoning{1. university,Dalian 1.6029,China 2 College of physics and Information Engineering,Henan{1. university,Xinxiang 453002,China Department of physics Liaoning Normal University Dalian 116029 College of physics and Information Engineering Henan Normal University Xinxiang 453002

Introduetion Altl、ough the standard model(SM)that bases on thega、lge gro、ip SU:(2)xU(1.has been sueeessful in de-seribing the Physies of eleetroweak interaetions,the meeh-anisn,of the eleetroweak symmetry breaking(... 详细信息

关键词： non-universal gauge bosons cross section TC2 models

Recurrence spectra of He atoms in strong external fields

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Science China(physics,Mechanics & Astronomy) 2004年第4期47卷 477-484页

作者： LIN Shenglu1. LI Hongyun1. WANG Dehua2, ZHAO Wenli1.& GAO Feng1.1. Department of physics, Shandong{1. university, Jinan 25001., China 2. Department of Mathematics and physics, Shandong institute of Architecture and Engineering, Jinan 25001., China 1. Department of physics Shandong Normal University 250014 Jinan China 2. Department of Mathematics and physics Shandong Institute of Architecture and Engineering 250014 Jinan China

By employing a model potential including the electron exchange energy, we extend the semiclassical closed orbit theory to study the multielectron atoms. Using special region-splitting consistent and iterative method, we figure out the closed orbits in the corresponding classical system and calculate the recurrence spectra of triplet helium atoms in parallel electric and magnetic fields at scaled energy ε=?0.03,n≈40,n=0. The core-scattering effects have been taken into account, which lead to more peaks in the spectra. It has also been confirmed by means of the direct comparison between the spectral portrait in such a plot and those of hydrogen case. In order to compare the theoretic results with experiment, we investigate the closed orbits and recurrence spectra of helium atoms for the similar exchange potential but applied only by single electric field at scaled energy ε=?2.7 case. The spectra are in good agreement with the experimental observation. We conclude that our model is correct and it is necessary to consider the exchange effect for determining the photoabsorption spectra of multielectron atoms in strong external fields.

关键词： exchange potential, recurrence spectra, semiclassical closed orbit theory, core-scattering.

Density functional theory study on the structural and electronic properties of Ag-adsorbed (MgO)_n clusters

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Science China(physics,Mechanics & Astronomy) 2009年第5期52卷 734-741页

作者： GE GuiXian1. JING Qun1.& LUO YouHua2,3 1.Key Laboratory of Ecophysics and Department of physics, normal College, Shihezi university, Shihezi 832003, China 2 School of Science, East China university of Science and Technology, Shanghai 200237, China 3 institute for theoretical physics, Henan university, Kaifeng 475004, China Key Laboratory of Ecophysics and Department of physics Normal College Shihezi University Shihezi 832003 China School of Science East China University of Science and Technology Shanghai 200237 China institute for{1. physics Henan University Kaifeng 475004 China

Equilibrium geometries, charge distributions, stabilities and electronic properties of the Ag-adsorbed (MgO)n (n = 1.8) clusters have been investigated by density functional theory (DFT) with generalized gradient approximation (GGA) for exchange-correlation functional. The results show that hollow site is energetically preferred for n≥4, and the incoming Ag atoms tend to cluster on the existing Ag cluster. The Mulliken populations indicate that the interaction between the Ag atom and Magnesia clusters is mainly induced by a weak atomic polarization. The adsorbed Ag atom only causes charge redistributions of the atoms near itself. The effect of the adsorbed Ag atom on the bonding natures and structural features of Magnesia clusters is minor. Furthermore, the investigations on the first energy difference, fragmentation energies and electron affinities show that the Ag(MgO)4 and Ag(MgO)6 are the most stable among studied clusters.

关键词： Ag (MgO)_n clusters geometries electronic properties

A computational investigation of boron-doped chromium and chromium clusters by density functional theory

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Science China(physics,Mechanics & Astronomy) 2010年第5期53卷 812-817页

作者： GE GuiXian1.JING Qun1.& LUO YouHua2,3 1.Key Laboratory of Ecophysics and Department of physics,normal College,Shihezi university,Xinjiang 832003,China 2 School of Science,East China university of Science and Technology,Shanghai 200237,China 3 institute of theoretical physics,School of physics and Information Optoelectronics,Henan university,Kaifeng 475004,China 1. Key Laboratory of Ecophysics and Department of physics Normal College Shihezi University Xinjiang 832003 China2. School of Science East China University of Science and Technology Shanghai 200237 China3. Institute of Theoretical Physics School of Physics and Information Optoelectronics Henan University Kaifeng 475004 China

The geometries,stabilities and electronic properties of Crn and CrnB(n=2-9) clusters have been systematically investigated by density functional *** results suggest that the lowest energy structures for CrnB clusters can be obtained by substituting one Cr atom in Crn+1.clusters with B *** geometries of CrnB clusters are similar to that of Crn+1.clusters except for local structural *** second-order difference and fragmentation energy show Cr4,Cr6,Cr8,Cr3B,Cr5B and Cr8B cluster are the most stable among these studied *** impurity B increases the stabilities of chromium *** B is doped on the Crn clusters,cluster geometry does dominate positive role in enhancing their *** doped B atom does not change the coupling way of the Cr site in Crn clusters,but breaks the symmetry and the Cr atoms are no longer *** doped B atom increases the total magnetic moments of Crn in most cases.

关键词： Crn and CrnB clusters geometries electronic properties

The geodetic numbers of graphs and digraphs

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Science China Mathematics 2007年第8期50卷 1163-1172页

作者： Chang-hong LU~(1.2) 1.Department of Mathematics,East China normal{1.,Shanghai 200062,China 2 institute of theoretical Computing,East China Narnal{1.,Shanghai 200062,China 1. Department of Mathematics East China Normal University Shanghai 200062 China 2. institute of{1. Computing East China Narnal University Shanghai 200062 China

For every two vertices u and v in a graph G, a u-v geodesic is a shortest path between u and v. Let I(u, v) denote the set of all vertices lying on a u-v geodesic. For a vertex subset S, let I(S) denote the union of all I(u, v) for u, v ∈ S. The geodetic number g(G) of a graph G is the minimum cardinality of a set S with I(S) = V (G). For a digraph D, there is analogous terminology for the geodetic number g(D). The geodetic spectrum of a graph G, denoted by S(G), is the set of geodetic numbers of all orientations of graph G. The lower geodetic number is g ?(G) = minS(G) and the upper geodetic number is g +(G) = maxS(G). The main purpose of this paper is to study the relations among g(G), g ?(G) and g +(G) for connected graphs G. In addition, a sufficient and necessary condition for the equality of g(G) and g(G × K 2) is presented, which improves a result of Chartrand, Harary and Zhang.

关键词： convex set digraph distance geodesic geodetic number 05C1. 05C20

C^MC^N D-computable state

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Science China(physics,Mechanics & Astronomy) 2008年第9期51卷 1300-1307页

作者： LIU DongDong1.2 & DI YaoMin1.1.School of physics & Electronic Engineering,Xuzhou{1. university,Xuzhou 221.1.,China 2 School of Mathematics & physics Science,Xuzhou institute of Technology,Xuzhou 221.08,China 1. School of physics & Electronic Engineering Xuzhou Normal University Xuzhou 221116 China 2. School of Mathematics & physics Science Xuzhou Institute of Technology Xuzhou 221008 China

The notions of D-computable state and D-concurrence are generalized to the CMCN system. A class of D-computable state on CMCN is given and the calculating method of the lower bound of D-concurrence is provided. Th... 详细信息

关键词： quantum entanglement entanglement of formation concurrence D-computable state

B→K~*γ Decay in Top-Quark Two-Higgs-Doublet Model

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Communications in theoretical{1. 2006年第11期46卷 895-900页

作者： XIAO Zhen-Jun,~+ CHENG Hui-Hui, and L Lin-Xia Department of physics and{1. of theoretical physics, Nanjing normal university, Nanjing 21.097, China Department of physics Nanjing Normal University institute of{1. physics Nanjing Normal University

By employing the QCD factorization approach for the exclusive B→Vγ decays, we study the exclusive decay B→K~*γ in the top-quark two-Higgs-doublet model (T2HDM). Within the considered parameter space, we find the following conclusions (a) A light charged-Higgs boson with a mass about 200 GeV is clearly excluded by the date of B→K~*γ decay, and this lower limit is comparable with that from the inclusive B→Xγ decay; (b) The theoretical predictions for CP asymmetry of B→K~*γ in the T2HDM is always less than 1. in size; and (c) The isospin symmetry breaking for B→K~*γ decay in the SM and T2HDM considered here is around 6% in size and well consistent with the data and the general expectations.

关键词： B meson decay charged-Higgs boson branching ratio CP asymmetry

Different-Periodic Travelling Wave Solutions for Nonlinear Equations

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Communications in theoretical{1. 2004年第4期41卷 481-486页

作者： YE Li-Jun~1.LIN Ji~(1.2)1.Department of physics,Zhejiang{1. university,Jinhua 321.04,China2 physics Department,Shanghai Jiao Tong university,Shanghai 200030,China physics Department Shanghai Jiao Tong University Shanghai 200030 China

Using Jacobi elliptic function linear superposition approach for the(1.1.-dimensional Caudrey-Dodd-Gibbon-Sawada-Kotera(CDGSK)equation and the(2+1.-dimensional Nizhnik-Novikov-Veselov(NNV)equation,many new periodic travelling wave solutions with different periods and velocities are obtained based on the knownperiodic *** procedure is crucially dependent on a sequence of cyclic identities involving Jacobi ellipticfunctions sn(ξ,m),cn(ξ,m),and dn(ξ,m).

关键词： linear superposition nonlinear equation travelling wave solution