2018年, 第70卷, 第02期　
刊出日期：2018-08-01

  

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  Solitons on a Periodic Wave Background of the Modified KdV-Sine-Gordon Equation

  林机, 金新伟, 高先龙, 楼森岳

  理论物理通讯. 2018, 70(02): 119-126.

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  The Bäcklund transformation(BT) of the mKdV-sG equation is constructed by introducing a new transformation. Infinitely many nonlocal symmetries are obtained in terms of its BT. The soliton-periodic wave interaction solutions are explicitly derived by the classical Lie-group reduction method. Particularly, some special concrete soliton and periodic wave interaction solutions and their behaviours are discussed both in analytical and graphical ways.
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  Quantifying Discriminating Strength for Gaussian States

  马瑞芬, 齐霄霏, 侯晋川

  理论物理通讯. 2018, 70(02): 127-131.

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  The discriminating strength D_S(ρ_AB) induced by local Gaussian unitary operators for any (n+m)-mode Gaussian state ρ_AB is introduced in[Phys. Rev. A 83 (2011) 042325]. In this paper, we further discuss the quantity by restricting to Hilbert-Schmidt norm. The analytic formulas of DS for two-mode squeezed thermal states and mixed thermal states are given. Then, the relationship between D_S(ρ_AB) and D_S((I ⊗ Φ)(ρ_AB)) for some special Gaussian channels Φ is discussed. In addition, D_S is compared with Gaussian entanglement for symmetric squeezed thermal states.
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  Solitary Vortex Evolution in Two-Dimensional Harmonically Trapped Bose-Einstein Condensates

  王颖, 周蜀渝

  理论物理通讯. 2018, 70(02): 132-136.

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  We investigate solitary vortex evolution in two-dimensional Bose-Einstein condensates based on the Gross-Pitaevskii equation model. Through the variational method, together with the novel Gaussian ansatz incorporating asymmetric perturbation effects, we arrive at the analytical solitary vortex solution with two typical forms:a symmetric quasi-stable solution under certain parametric settings and a diverging propagation case arising from an initial asymmetric perturbation. The derived pictorial evolutionary patterns of the solitary vortices are compared with those from a pure numerical analysis, and by identifying the key qualitative features, we show the applicability of the theoretical treatment presented here.
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  Sufficient Conditions of the Same State Order Induced by Coherence

  张福刚, 李永明

  理论物理通讯. 2018, 70(02): 137-144.

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  In this paper, we study coherence-induced state ordering with Tsallis relative entropy of coherence, relative entropy of coherence and l₁ norm of coherence, and give the sufficient conditions of the same state order induced by above coherence measures. First, we show that the above measures give the same ordering for single-qubit states in some special cases. Second, we consider some special states in a d-dimensional quantum system. We show that the above measures generate the same ordering for these special states. Finally, we discuss dynamics of coherence-induced state ordering under Markovian channels. We find amplitude damping channel changes the coherence-induced ordering even though for single-qubit states with fixed mixedness.
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  An Approximate Approach for Systems of Singular Volterra Integral Equations Based on Taylor Expansion

  Mohsen Didgar, Alireza Vahidi

  理论物理通讯. 2018, 70(02): 145-152.

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  In this article, an extended Taylor expansion method is proposed to estimate the solution of linear singular Volterra integral equations systems. The method is based on combining the m-th order Taylor polynomial of unknown functions at an arbitrary point and integration method, such that the given system of singular integral equations is converted into a system of linear equations with respect to unknown functions and their derivatives. The required solutions are obtained by solving the resulting linear system. The proposed method gives a very satisfactory solution, which can be performed by any symbolic mathematical packages such as Maple, Mathematica, etc. Our proposed approach provides a significant advantage that the m-th order approximate solutions are equal to exact solutions if the exact solutions are polynomial functions of degree less than or equal to m. We present an error analysis for the proposed method to emphasize its reliability. Six numerical examples are provided to show the accuracy and the efficiency of the suggested scheme for which the exact solutions are known in advance.
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  Higher-Order Rogue Wave Pairs in the Coupled Cubic-Quintic Nonlinear Schrödinger Equations

  徐涛, 陳偉康, 陈勇

  理论物理通讯. 2018, 70(02): 153-160.

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  We study some novel patterns of rogue wave in the coupled cubic-quintic nonlinear Schrödinger equations. Utilizing the generalized Darboux transformation, the higher-order rogue wave pairs of the coupled system are generated. Especially, the first-and second-order rogue wave pairs are discussed in detail. It demonstrates that two classical fundamental rogue waves can be emerged from the first-order case and four or six classical fundamental rogue waves from the second-order case. In the second-order rogue wave solution, the distribution structures can be in triangle, quadrilateral and ring shapes by fixing appropriate values of the free parameters. In contrast to single-component systems, there are always more abundant rogue wave structures in multi-component ones. It is shown that the two higher-order nonlinear coefficients ρ₁ and ρ₂ make some skews of the rogue waves.
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  Gravity and Spin Forces in Gravitational Quantum Field Theory

  吴岳良, 张睿

  理论物理通讯. 2018, 70(02): 161-174.

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  In the new framework of gravitational quantum field theory (GQFT) with spin and scaling gauge invariance developed in Phys. Rev. D 93 (2016) 024012-1, we make a perturbative expansion for the full action in a background field which accounts for the early inflationary universe. We decompose the bicovariant vector fields of gravifield and spin gauge field with Lorentz and spin symmetries SO(1,3) and SP(1,3) in biframe spacetime into SO(3) representations for deriving the propagators of the basic quantum fields and extract their interaction terms. The leading order Feynman rules are presented. A tree-level 2 to 2 scattering amplitude of the Dirac fermions, through a gravifield and a spin gauge field, is calculated and compared to the Born approximation of the potential. It is shown that the Newton's gravitational law in the early universe is modified due to the background field. The spin dependence of the gravitational potential is demonstrated.
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  SUSY Confinement

  赵树民, 李学潜

  理论物理通讯. 2018, 70(02): 175-178.

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  In response to the present status that searching for SUSY particles has been unsuccessful, we propose a bold scenario that SUSY particles are confined inside hadrons with a required condition of P_R=1 in analog to the color confinement for quarks. The scenario seems to be able to reconcile the beautiful SUSY theory and non-observation at present experiments. On other aspects, some loopholes in the proposal emerge and require to be answered in the future research.
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  Mass Spectra of Heavy and Light Mesons Using Asymptotic Iteration Method

  Richa Rani, S. B. Bhardwaj, Fakir Chand

  理论物理通讯. 2018, 70(02): 179-184.

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  The non-relativistic radial Schrödinger equation is analytically solved using asymptotic iteration method within the framework of a general interaction potential whose special cases are the Cornell and Cornell plus harmonic potentials. The energy eigenvalues expression is derived in three dimensional space, which is further used to calculate the mass spectra of cc, bb, bc, cs, bs and bq mesons. The obtained results of this work are in good agreement with experimental and other relativistic results and also improved in comparison with other non-relativistic recent studies.
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  Spherical Gravitational Collapse in f(R) Gravity with Linear Equation of State

  Zahid Ahmad, Hassan Shah, Suhail Khan

  理论物理通讯. 2018, 70(02): 185-189.

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  In a paper[Gen. Relativ. Gravit. 48 (2016) 57] Chakrabarti and Banerjee investigated perfect fluid collapse in f(R) gravity model and claimed that such a collapse is possible. In this paper we show that without the assumption of dark energy it is not possible that perfect fluid spherical gravitational collapse will occur. We have solved the field equations by assuming linear equation of state (p=ωμ) in metric f(R) gravity with ω=-1. It is shown that Chakrabarti and Banerjee reached to false conclusion as they derived wrong field equations. We have also discussed formation of apparent horizon and singularity.
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  Energy Bounds for Static Spherically Symmetric Spacetime in f(R,G) Gravity

  M. Farasat Shamir, Ayesha Komal

  理论物理通讯. 2018, 70(02): 190-196.

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  The main purpose of this paper is to investigate energy bounds in the context of f(R,G) gravity. To meet this aim, we choose static spherically symmetric spacetime in f(R,G) gravity to develop the field equations. We select three different models of f(R,G) gravity, which are thoroughly discussed in the literature. Firstly, the inequalities are formulated using energy bounds and then viability of the considered models are checked respectively. Graphical analysis show that specific f(R,G) gravity models are satisfied under suitable values of model parameters. It is shown that in a certain case energy bounds are satisfied expect SEC, which supports the late time acceleration expansion of unverse.
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  Self-Similar Solution of Spherical Shock Wave Propagation in a Mixture of a Gas and Small Solid Particles with Increasing Energy under the Influence of Gravitational Field and Monochromatic Radiation

  P. K. Sahu

  理论物理通讯. 2018, 70(02): 197-208.

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  Similarity solution for a spherical shock wave with or without gravitational field in a dusty gas is studied under the action of monochromatic radiation. It is supposed that dusty gas be a mixture of perfect gas and micro solid particles. Equilibrium flow condition is supposed to be maintained and energy is varying which is continuously supplied by inner expanding surface. It is found that similarity solution exists under the constant initial density. The comparison between the solutions obtained in gravitating and non-gravitating medium is done. It is found that the shock strength increases with an increase in gravitational parameter or ratio of the density of solid particles to the initial density of the gas, whereas an increase in the radiation parameter has decaying effect on the shock waves.
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  Jeans Instability of Self Gravitating Dust Cloud in Presence of Effective Electrostatic Pressure

  Pratikshya Bezbaruah, Pritam Das, Prathana Borah, Nilakshi Das

  理论物理通讯. 2018, 70(02): 209-214.

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  The role of viscosity coefficient (η'), coulomb coupling parameter (Γ) and dust mass on the growth of jeans mode is investigated in strongly coupled dusty plasma using equations of Generalized Hydrodynamics (GH) Model. The novel aspect of this work is that the force arising due to electrostatic pressure caused by grain grain interaction has been included in the dynamics of dust particles. This force is found to play a significant role in counter balancing the self gravity effect, thereby reducing the growth rate of jeans instability. The present work may provide more physical insight in understanding the mechanisms behind formation of planetesimals, stars etc.
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  Phase Sensitive Photonic Flash

  崔馨匀, 王治海, 吴金辉

  理论物理通讯. 2018, 70(02): 215-219.

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  We theoretically propose a photonic flash based on a linearly coupled cavity system. Via driving the two side cavities by external fields, it forms a cyclic energy-level diagram and therefore the phase difference between the driving fields acts as a controller of the steady state due to the quantum interference effect. In the optical trimer structure, we show that the perfect photonic flash can be realized in the situation of resonant driving. The perfect photonic flash scheme is furthermore generalized to multiple coupled cavity system, where the cavities with odd and even number turn bright and dark alternatively. Our proposal may be applied for designing the quantum neon and realizing a controllable photonic localization.
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  Effect of Critical Beam Radius on Self-focusing of cosh-Gaussian Laser Beams in Collisionless Magnetized Plasma

  T. U. Urunkar, S. D. Patil, A. T. Valkunde, B. D. Vhanmore, K. M. Gavade, M. V. Takale

  理论物理通讯. 2018, 70(02): 220-224.

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  Effect of critical beam radius on self-focusing of cosh-Gaussian laser beams in collisionless magnetized plasma under ponderomotive nonlinearity forms the main core of present work. To investigate propagation dynamics of cosh-Gaussian laser beams in collisionless magnetized plasma, well established parabolic equation approach under WKB and paraxial approximations is employed. Our study is crucially pivoted on the concept of critical curve and subsequent determination of numerical interval for decentered parameter to sustain the competition between diffraction and self-focusing during the propagation of laser beam. Additionally, in the present study an interesting feature in the self-focusing region of the critical curve has been attempted for different values of decentered parameter.
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  Energy Transfer in the Light-Harvesting Complexes of Purple Bacteria

  何贝贝, 明蒙蒙, 刘昌勇, 王国栋, 覃莉, 李有为

  理论物理通讯. 2018, 70(02): 225-229.

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  In this paper, we use a nonlinear decohering quantum model to study the initial step of photosynthesis which is an ultrafast transfer process of absorption the sunlight by light-harvesting complexes and electronic excitation transfer to the reaction center (RC). In this decohering model, the Hamiltonian of the system commutes with the systemenvironment interaction. We take B850 ring of light-harvesting complex Ⅱ (LH-Ⅱ) in purple bacteria as an example to calculate the efficiency of the energy transfer as a function of time. We find that the environmental noise can make the LH-Ⅱ have stable energy transfer efficiency over a long time. This is to say that the environmental noise which is the decohering source has advantage of the energy transfer in the process of photosynthesis.
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  Effects of Thermal Radiation on a 3D Sisko Fluid over a Porous Medium Using Cattaneo-Christov Heat Flux Model

  Deog-Hee Doh, M. Muthtamilselvan, E. Ramya, P. Revathi

  理论物理通讯. 2018, 70(02): 230-238.

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  This paper investigates the three-dimensional flow of a Sisko fluid over a bidirectional stretching sheet, in a porous medium. By using the effect of Cattaneo-Christov heat flux model, heat transfer analysis is illustrated. Using similarity transformation the governing partial differential equations are transferred into a system of ordinary differential equations that are solved numerically by applying Nachtsheim-Swigert shooting iteration technique along with the 6-th order Runge-Kutta integration scheme. The effect of various physical parameters such as Sisko fluid, ratio parameter, thermal conductivity, porous medium, radiation parameter, Brownian motion, thermophoresis, Prandtl number, and Lewis number are graphically represented.
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  A Numerical Investigation of Nanocomposite of Copper and Titanium Dioxide in Water Based Fluid Influenced by Instigated Magnetic Region

  Z. Iqbal, Ehtsham Azhar, E. N. Maraj, Zaffar Mehmood

  理论物理通讯. 2018, 70(02): 239-248.

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  Presence of external electrical field plays a vital role in heat transfer and fluid flow phenomena. Keeping this in view present article is a numerical investigation of stagnation point flow of water based nanoparticles suspended fluid under the influence of induced magnetic field. A detailed comparative analysis has been performed by considering Copper and Titanium dioxide nanoparticles. Utilization of similarity analysis leads to a simplified system of coupled nonlinear differential equations, which has been tackled numerically by means of shooting technique followed by Runge-Kutta of order 5. The solutions are computed correct up to 6 decimal places. Influence of pertinent parameters is examined for fluid flow, induced magnetic field, and temperature profile. One of the key findings includes that magnetic parameter plays a vital role in directing fluid flow and lowering temperature profile. Moreover, it is concluded that Cu-water based nanofluid high thermal conductivity contributes in enhancing heat transfer efficiently.