2015年, 第64卷, 第01期　
刊出日期：2015-07-01

  

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  Particles and Scalar Waves in Noncommutative Charged Black Hole Spacetime

  Piyali Bhar, Farook Rahaman, Ritabrata Biswas, U. F. Mondal

  理论物理通讯. 2015, 64(01): 1-8.

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  In this paper we have discussed geodesics and the motion of test particle in the gravitational field of noncommutative charged black hole spacetime. The motion of massive and massless particle have been discussed seperately. A comparative study of noncommutative charged black hole and usual Reissner—Nordström black hole has been done. The study of effective potential has also been included. Finally, we have examined the scattering of scalar waves in noncommutative charged black hole spacetime.
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  On Calculations of Legendre Functions and Associated Legendre Functions of the First Kind of Complex Degree

  Karl-Erik Thylwe, Patrick McCabe

  理论物理通讯. 2015, 64(01): 9-12.

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  Formulas for calculating Legendre functions and associated Legendre functions of the first kind of complex degree using an Ermakov—Lewis invariant are presented. These formulas are straight-forward to implement numerically and are motivated by the lack of computational routines in standard university tools like those of MatLab and Maple. Angular waves propagating in opposite directions are also obtained. The results are particularly useful in complex angular momentum theories and nearside/farside analysis of spin-dependent angular scattering from central potentials.
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  Beltrami—McKeon—Schubert Realizations of osp(1|4) Algebra and Possible Supersymmetric Kinematics

  李林, 黄超光

  理论物理通讯. 2015, 64(01): 13-21.

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  The possible supersymmetric kinematics are presented by the contraction method in different limits from Beltrami—McKeon—Schubert realizations of osp(1|4). The connections among the superalgebras are established. The comparison with the superalgebras contracted from Beltrami—Ivanov—Sorini realization is made.
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  Analytical Solution of Partial-Wave Faddeev Equations with Application to Scattering and Statistical Mechanical Properties

  ALI Maghari, VAHDAT Moheb

  理论物理通讯. 2015, 64(01): 22-28.

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  In this work, the Faddeev equations for three-body scattering at arbitrary angular momentum are exactly solved and the transition matrices for some transition processes, including scattering and rearrangement channels are formulated in terms of free-particle resolvent matrix. A generalized Yamaguchi rank-two nonlocal separable potential has been used to obtain the analytical expressions for partial wave scattering properties of a three-particle system. The partial-wave analysis for some transition processes in a three-particle system is suggested. The partial-wave three-particle transition matrix elements have been constructed via knowledge of the matrix elements of the free motion resolvent. The calculation of a number of scattering properties of interest of the system such as transition matrix and its poles (bound states and resonances) and consequently other related quantities like scattering amplitudes, scattering length, phase shifts and cross sections are feasible in a straightforward manner. Moreover, we obtain a new analytical expression for the third virial coefficient in terms of three-body transition matrix.
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  Reference Section Method for Mixed State Geometric Phase in Nonunitary Evolution

  杜光乐, 李田军

  理论物理通讯. 2015, 64(01): 29-33.

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  We propose the reference section method to obtain a geometric phase for the mixed states in nonunitary evolution. The reference connection on density operator space is defined. That the parallel transport method and reference section method are essentially two aspects of in phase concept is pointed out.
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  Spin Number Coherent States and the Problem of Two Coupled Oscillators

  D. Ojeda-Guillén, R. D. Mota, V. D. Granados

  理论物理通讯. 2015, 64(01): 34-38.

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  From the definition of the standard Perelomov coherent states we introduce the Perelomov number coherent states for any su(2) Lie algebra. With the displacement operator we apply a similarity transformation to the su(2) generators and construct a new set of operators which also close the su(2) Lie algebra, being the Perelomov number coherent states the new basis for its unitary irreducible representation. We apply our results to obtain the energy spectrum, the eigenstates and the partition function of two coupled oscillators. We show that the eigenstates of two coupled oscillators are the SU(2) Perelomov number coherent states of the two-dimensional harmonic oscillator with an appropriate choice of the coherent state parameters.
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  Non-equilibrium Dynamics of an Optomechanical Dicke Model

  Kamanasish Debnath, Aranya B. Bhattacherjee

  理论物理通讯. 2015, 64(01): 39-46.

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  Motivated by the experimental realization of Dicke model in optical cavities, we model an optomechanical system consisting of two-level BEC atoms with transverse pumping. We investigate the transition from normal and inverted state to the superradiant phase through a detailed study of the phase portraits of the system. The rich phase portraits generated by analytical arguments display two types of superradiant phases, regions of coexistence and some portion determining the persistent oscillations. We study the time evolution of the system from any phase and discuss the role of mirror frequency in reaching their attractors. Further, we add an external mechanical pump to the mirror which is capable of changing the mirror frequency through radiation pressure and study the impact of the pump on the phase portraits and the dynamics of the system. We find the external mirror frequency changing the phase portraits and even shifting the critical transition point, thereby predicting a system with controllable phase transition.
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  Nonlinearity of Quantum Mechanics and Solution of the Problem of Wave Function Collapse

  Alexey V. Melkikh

  理论物理通讯. 2015, 64(01): 47-53.

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  The problem of the wave function collapse (a problem of measurement in quantum mechanics) is considered. It is shown that it can be solved based on quantum mechanics and does not require any additional assumptions or new theories. The particle creation and annihilation processes, which are described based on quantum field theory, play a key role in the measurement processes. Superposition principle is not valid for the system of equations of quantum field theory for particles and fields, because this system is a non-linear. As a result of the creation (annihilation) of a particle, an additional uncertainty arises, which "smears" the interference pattern. The imposition of such a large number of uncertainties in the repetitive measurements leads to the classical behavior of particles. The decoherence theory also implies the creation and annihilation of particles, and this processes are the consequence of non-linearity of quantum mechanics. In this case, the term "collapse of the wave function" becomes a consequence of the other statements of quantum mechanics instead of a separate postulate of quantum mechanics.
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  OJ287: Post-Newtonian Calculation in Harmonic Coordinate and Pulsar Timing Residual Confirmation

  程斌, 张杨

  理论物理通讯. 2015, 64(01): 54-58.

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  We calculate and discuss the motion of the binary black hole OJ287 based on Post-Newtonian approximation in a harmonic coordinate. With gravitational waveform obtained, theoretical timing residual of PSR B1855+09 induced by gravitational radiation of OJ287 is presented and compared with observed data, further shows that hypothesis referring to OJ287 as a binary BH system might be proper. The energy flux of gravitational radiation from binary is also provided, from which we find that the flux changes sign successively: ?_N >0, ?_1PN <0, ?_2PN >0, in agreement with the relative signs of forces of each PN order, revealed in the previous work.
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  Various Types of Kink and Bright Resonant Soliton Solutions for the (2+1)-Dimensional Double sine-Gordon Equation

  林机, 黄光侨, 陈伟雄

  理论物理通讯. 2015, 64(01): 59-66.

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  The algebraic mapping relations between the (2+1)-dimensional double sine-Gordon equation and the cubic nonlinear Klein—Gordon equation are constructed. Many new types of two-dimensional resonant kink, bright soliton and solitoff solutions are obtained, such as broken line shape, "V" shape, "snake" shape and "M" shape solitary waves, Zigzag-curve type, "ω" shape, peroidic-curve type, oscillatory Arch-type and parabolic shape bright soliton waves. We also investigate the propagating properties of some soliton solutions.
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  Vector Breathers in an Averaged Dispersion-Managed Birefringent Fiber System

  理记涛, 韩金钟, 张献图

  理论物理通讯. 2015, 64(01): 67-70.

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  A variable-coefficient coupled nonlinear Schrödinger equation in an averaged dispersion-managed birefringent fiber is investigated. Based on the one-to-one correspondence between variable-coefficient and constant-coefficient equations, an analytical breather solution is derived. As an example to exhibit dynamical behaviors of solution, its controllable excitations including rear excitation, peak excitation and initial excitation are discussed.
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  (2+1)-Dimensional Spatial Localized Modes in Cubic-Quintic Nonlinear Media with the PT-Symmetric Potentials

  陈翼翔, 徐周翔, 蒋云峰, 史进, 徐方迁

  理论物理通讯. 2015, 64(01): 71-80.

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  We obtain exact spatial localized mode solutions of a (2+1)-dimensional nonlinear Schrödinger equation with constant diffraction and cubic-quintic nonlinearity in PT-symmetric potential, and study the linear stability of these solutions. Based on these results, we further derive exact spatial localized mode solutions in a cubic-quintic medium with harmonic and PT-symmetric potentials. Moreover, the dynamical behaviors of spatial localized modes in the exponential diffraction decreasing waveguide and the periodic distributed amplification system are investigated.
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  Algebro-Geometric Solutions with Characteristics of a Nonlinear Partial Differential Equation with Three-Potential Functions

  张玉峰, 冯滨鲁, 芮文娟, 张祥芝

  理论物理通讯. 2015, 64(01): 81-89.

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  With the help of a simple Lie algebra, an isospectral Lax pair, whose feature presents decomposition of element (1, 2) into a linear combination in the temporal Lax matrix, is introduced for which a new integrable hierarchy of evolution equations is obtained, whose Hamiltonian structure is also derived from the trace identity in which contains a constant γ to be determined. In the paper, we obtain a general formula for computing the constant γ. The reduced equations of the obtained hierarchy are the generalized nonlinear heat equation containing three-potential functions, the mKdV equation and a generalized linear KdV equation. The algebro-geometric solutions (also called finite band solutions) of the generalized nonlinear heat equation are obtained by the use of theory on algebraic curves. Finally, two kinds of gauge transformations of the spatial isospectral problem are produced.
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  Energy Staggering in Ground Bands of ²³²Th and ^236,238U Nuclei Using the Interacting Vector Boson Model

  A.M. Khalaf, M. M. Sirag, M. Kotb

  理论物理通讯. 2015, 64(01): 90-94.

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  The ΔI=2 and ΔI=4 staggering parameters of transition energies E_γ for normally deformed positive parity ground bands in ²³²Th and ^236,238U nuclei are studied in framework of the symplectic extension of the interacting vector boson model. The model parameters are obtained from the fitting procedure between the calculated excitation energies and the corresponding experimental ones. The staggering parameters represent the finite difference approximations to higher order derivatives dⁿE_γ/d Iⁿ of the γ -ray transition energies in a ΔI=2 and ΔI=4 bands, which yielding multipoint formulae. The first order derivative (two-point formula) provides us with information about the dynamical moment of inertia. The staggering oscillation for the fourth order derivative (five-point formula) is about 0.5 KeV and is even larger than that in superdeformed bands. The quite similarity in dynamical moments of inertia of the isotopes ^236,238U up to high spin states indicate that the phenomenon of identical bands is not restricted to superdeformed bands.
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  Centrality Dependence of Productions for Single Hadrons and Inclusive Jets in High-Energy p+A Collisions with NLO QCD

  陈时勇, 申可明, 代巍, 张本威, 张汉中, 王恩科

  理论物理通讯. 2015, 64(01): 95-102.

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  By using the recent spatially dependent nuclear PDF set EPS09s, we investigated the centrality-dependent Cold Nuclear Matter (CNM) effects for neutral π, η mesons and inclusive jets at RHIC in d+Au collisions and at LHC in p+Pb collisions. The nuclear modification factors as functions of transverse momentum are plotted at different centralities bins respectively. At all fixed centralities, the nuclear modification factors show no significant suppressions, contrast to the strong suppressions observed for central Au+Au collisions. Our results are consistent with the PHENIX preliminary Data in minimum bias and central d+Au collisions. The LHC experimental Data also support our predictions for both single inclusive hadron and inclusive jets productions in central p+Pb collisions. And the centrality dependence of the nuclear suppressions for all the observations in our calculations are lower than the RHIC and LHC Data.
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  Density Transition Based Self-Focusing of cosh-Gaussian Laser Beam in Plasma with Linear Absorption

  Niti Kant, Manzoor Ahmad Wani

  理论物理通讯. 2015, 64(01): 103-107.

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  Density transition based self-focusing of cosh-Gaussian laser beam in plasma with linear absorption has been studied. The field distribution in the plasma is expressed in terms of beam width parameter, decentered parameter, and linear absorption coefficient. The differential equation for the beam width parameter is solved by following Wentzel—Kramers—Brillouin (WKB) and paraxial approximation through parabolic wave equation approach. The behaviour of beam width parameter with dimensionless distance of propagation is studied at optimum values of plasma density, decentered parameter and with different absorption levels in the medium. The results reveal that these parameters can affect the self-focusing significantly.
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  Anisotropic Short-Wavelength Friedel Oscillation with Adjustable Envelope in Graphene

  陈健, 许怀哲

  理论物理通讯. 2015, 64(01): 108-112.

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  We investigate theoretically the intervalley charge density oscillation and the screened ionic potential in graphene caused by the intervalley scattering. We demonstrate that the contribution from the intervalley scattering is comparable with that from the intravalley scattering, and oscillation rather than decaying dominates at a large distance away from the external impurity. We show that the intervalley oscillation is strongly anisotropic because of the inequivalency between neighboring valleys. The anisotropic oscillation consists of an anisotropic short-wavelength oscillation with an anisotropic fixed wavelength and an isotropic long-wavelength envelop with an isotropic wavelength modulated by doping, making an adjustable-widthed wave-packet propagation. One weakens the screening and gets anisotropic short-wavelength oscillation by introducing short-range mechanism in graphene and graphene-like materials.
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  Composition Dependence of Electrocaloric Effect in (1-x)Pb(Mg_1/3Nb_2/3)O_3-xPbTiO₃ Single Crystals

  邱建华, 王秀琴, 袁宁一, 丁建宁

  理论物理通讯. 2015, 64(01): 113-118.

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  Composition dependence of electrocaloric effect is investigated in (1-x)Pb(Mg_1/3Nb_2/3)O_3-xPbTiO₃ single crystals by using an eighth-order Landau—Devonshire theory. The applied electric field along [001] direction reduces the ferroelectric-ferroelectric phase transition temperatures, but increases the Curie temperatures. The electrocaloric coefficients of tetragonal phase are much larger than that of rhombohedral and monoclinic phase. A negative electrocaloric effect is observed near the M_C-T phase transition in 0.69 Pb(Mg_1/3Nb_2/3)O₃-0.31 PbTiO₃ single crystal. The application of a strong enough electric field results in a high adiabatic temperature change over a broad range of temperature. Therefore, it would be useful to construct a solid state cooling cycle over a broad temperature range for practical applications.
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  Direct Detection of Dark Matter with Resonant Annihilation

  李博, 周宇峰

  理论物理通讯. 2015, 64(01): 119-126.

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  In the scenario where the dark matter (DM) particles χχ pair annihilate through a resonance particle R, the constraint from DM relic density makes the corresponding cross section for DM-nuclei elastic scattering extremely small, and can be below the neutrino background induced by the coherent neutrino-nuclei scattering, which makes the DM particle beyond the reach of the conventional DM direct detection experiments. We present an improved analytical calculation of the DM relic density in the case of resonant DM annihilation for s- and p-wave cases and invesitgate the condition for the DM-nuclei scattering cross section to be above the neutrino background. We show that in Higgs-portal type models, for DM particles with s-wave annihilation, the spin-independent DM-nucleus scattering cross section is proportional to Γ_R/m_R, the ratio of the decay width and the mass of R. For a typical DM particle mass ～50 GeV, the condition leads to Γ_R/m_R ≥O(10^-4). In p-wave annihilation case, the spin-independent scattering cross section is insensitive to Γ_R/m_R, and is always above the neutrino background, as long as the DM particle is lighter than the top quark. The real singlet DM model is discussed as a concrete example.