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arXiv 2020年

作者： Gong, Yuezheng Hong, Qi Wang, Qi College of Science Nanjing University of Aeronautics and Astronautics Nanjing210016 China Beijing Computational Science Research Center Beijing100193 China Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Department of Mathematics University of South Carolina ColumbiaSC29208 United States

We present a new temporal discretization paradigm for developing energy-production-rate preserving numerical approximations to thermodynamically consistent partial differential equation systems, called the supplementary variable method. The central idea behind it is to introduce a supplementary variable to the thermodynamically consistent model to make the over-determined equation system, consisting of the thermodynamically consistent PDE system, the energy definition and the energy dissipation equation, structurally stable. The supplementary variable allows one to retain the consistency between the energy dissipation equation and the PDE system after the temporal discretization. We illustrate the method using a dissipative gradient flow model. Among virtually infinite many possibilities, we present two ways to add the supplementary variable in the gradient flow model to develop energy-dissipation-rate preserving algorithms. Spatial discretizations are carried out using the pseudo-spectral method. We then compare the two new schemes with the energy stable SAV scheme and the fully implicit Crank-Nicolson scheme. The results favor the new schemes in the overall performance. This new numerical paradigm can be applied to any thermodynamically consistent models. Copyright © 2020, The Authors. All rights reserved.

关键词： Partial differential equations

Hidden-charm tetraquarks with strangeness in the chiral quark model

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Physical Review D 2021年第9期104卷 094035-094035页

作者： Gang Yang Jialun Ping Jorge Segovia Department of Physics Zhejiang Normal University Jinhua 321004 China Department of Physics and Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing 210023 People’s Republic of China Departamento de Sistemas Físicos Químicos y Naturales Universidad Pablo de Olavide E-41013 Sevilla Spain

The hidden-charm tetraquarks with strangeness, cc¯sq¯ (q=u, d), in JP=0+, 1+, and 2+ are systematically investigated in the framework of real- and complex-scaling range of a chiral quark model, whose parameters have been fixed in advance describing hadron, hadron-hadron, and multiquark phenomenology. Each tetraquark configuration, compatible with the quantum numbers studied, is taken into account; this includes meson-meson, diquark-antidiquark, and K-type arrangements of quarks with all possible color wave functions in the four-body sector. Among the different numerical techniques to solve the Schrödinger-like four-body bound state equation, we use a variational method in which the trial wave function is expanded in complex-range Gaussian basis functions, which is characterized by its simplicity and flexibility. This theoretical framework has already been used to study different kinds of multiquark systems, such as the hidden-charm pentaquarks Pc+ and doubly charmed tetraquarks Tcc+. The recently reported Zcs states by the BESIII and LHCb Collaborations could be associated, in our investigation, with either compact tetraquark or hadronic molecular resonance configurations. However, it is fair to recognize that our complex poles survive when either the (cc¯)(sq¯) or (cq¯)(sc¯) configuration is preserved, but most of them get diluted when both are considered at the same time, indicating that such states seem to be very unstable. Finally, we mention that similar types of structures are also found in the mass range between 3.8 and 4.6 GeV.

关键词： Many-body techniques Quantum chromodynamics Quark model Strong interaction

Bottomoniumlike tetraquarks in a chiral quark model

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Physical Review D 2022年第1期106卷 014021-014021页

The low-lying bottomoniumlike tetraquarks bb¯qq¯ (q=u, d, s) with spin-parity JP=0+, 1+, and 2+, and isospin I=0, 1, or 12, are systematically investigated within the theoretical framework of real- and complex-scaling range of a chiral quark model, which has already been successfully applied in analysis of several multiquark systems. A complete four-body S-wave function, which includes meson-meson, diquark-antidiquark and K-type arrangements of quarks, along with all possible color configurations are considered. In the bb¯qq¯ (q=u, d) tetraquark system, we found resonance states of B(*)B¯(*), ϒω, ϒρ, and ηbρ nature with all possible I(JP) quantum numbers. Their masses are generally located in the energy range 11.0–11.3 GeV and their widths are less than 10 MeV. In addition, extremely narrow resonances, with two-meson strong decay widths less than 1.5 MeV, are obtained in both bb¯us¯ and bb¯ss¯ tetraquark systems. Particularly, four radial excitations of ϒK* and ηbK* are found at ∼11.1 GeV in JP=0+, 1+, and 2+ channels of bb¯us¯ system. One ϒ(1S)ϕ(2S) resonance state is obtained at 11.28 GeV in the JP=1+ sector.

关键词： Quantum chromodynamics Quark model Strong interaction

Directed momentum current induced by the PT-symmetric driving

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Physical Review E 2019年第4期99卷 042201-042201页

作者： Wen-Lei Zhao Jiaozi Wang Xiaohui Wang Peiqing Tong School of Science Jiangxi University of Science and Technology Ganzhou 341000 China Department of Modern Physics University of Science and Technology of China Hefei 230026 China School of Information Engineering Jiangxi University of Science and Technology Ganzhou 341000 China Department of Physics and Institute of Theoretical Physics Nanjing Normal University Nanjing 210023 China Jiangsu Provincial Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing Jiangsu 210023 China

We investigate the directed momentum current in the quantum kicked rotor model with PT-symmetric deriving potential. For the quantum nonresonance case, the values of quasienergy become complex when the strength of the imaginary part of the kicking potential exceeds a threshold value, which demonstrates the appearance of the spontaneous PT symmetry breaking. In the vicinity of the transition point, the momentum current exhibits a staircase growth with time. Each platform of the momentum current corresponds to the mean momentum of some eigenstates of the Floquet operator whose imaginary parts of the quasienergy are significantly large. Above the transition point, the momentum current increases linearly with time. Interestingly, its acceleration rate exhibits a kind of “quantized” increment with the kicking strength. We propose a modified classical acceleration mode of the kicked rotor model to explain such an intriguing phenomenon. Our theoretical prediction is in good agreement with numerical results.

关键词： Coherent control Cold atoms & matter waves Light-matter interaction Wave chaos

Evaluation method for information security capability of mobile phone user based on behavior ontology under unconscious condition

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Tongxin Xuebao/Journal on Communications 2016年 37卷 156-167页

作者： Mai, Cheng-Cheng Chen, Bo Zhou, Jia-Kun Yu, Ling School of Computer Science and Technology Nanjing Normal University Nanjing210023 China Jiangsu Provincial Key Laboratory for Numerical of Large Scale Complex System Nanjing210023 China

A security capacity assessment method based on security behavior ontology, was proposed to collect users' behavior data from their smartphones under unconscious condition to solve the problem of detecting mobile phone users' real existing insecure behaviors. A security behavior ontology was set up for formalizing the phone, message, network and App behavior data of mobile phone users and relevant rules were also set down for determining and associating insecure actions. Referring to the notion of attack graph, an insecure behavior detection algorithm was proposed based on behavior association graph for analyzing the paths of insecure behaviors dynamically. Furthermore, a competency model of information security capability assessment was presented for realizing the quantitative evaluation of information security capability of users. The experiment results prove the effectiveness of present competency model for insecure behavior path detection and security ability assessment. © 2016, Editorial Board of Journal on Communications. All right reserved.

关键词： Ontology

Arbitrarily high-order structure-preserving schemes for the Gross-Pitaevskii equation with angular momentum rotation in three dimensions

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arXiv 2020年

作者： Cui, Jin Wang, Yushun Jiang, Chaolong Department of Basic Sciences Nanjing Vocational College of Information Technology Nanjing210023 China Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems School of Mathematical Sciences Nanjing Normal University Nanjing210023 China School of Statistics and Mathematics Yunnan University of Finance and Economics Kunming650221 China

In this paper, we design a novel class of arbitrarily high-order structure-preserving numerical schemes for the time-dependent Gross-Pitaevskii equation with angular momentum rotation in three dimensions. Based on the idea of the scalar auxiliary variable approach which is proposed in the recent papers [J. Comput. Phys., 416 (2018) 353-407 and SIAM Rev., 61(2019) 474-506] for developing energy stable schemes for gradient flow systems, we firstly reformulate the Gross-Pitaevskii equation into an equivalent system with a modified energy conservation law. The reformulated system is then discretized by the Gauss collocation method in time and the standard Fourier pseudo-spectral method in space, respectively. We show that the proposed schemes can preserve the discrete mass and modified energy exactly. numerical results are addressed to verify the efficiency and high-order accuracy of the proposed schemes. Copyright © 2020, The Authors. All rights reserved.

关键词： Bose-Einstein condensation

Rho-pion transition form factors in the kT factorization formulism revisited

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arXiv 2018年

作者： Hua, Jun Cheng, Shan Zhang, Ya-Lan Xiao, Zhen-Jun Department of Physics and Institute of Theoretical Physics Nanjing Normal University Nanjing Jiangsu210023 China School of Physics and Microelectronics Science Hunan University Changsha Hunan410082 China Department of Faculty of Mathematics and Physics Huaiyin Institute of Technology Huaian Jiangsu223001 China Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing Jiangsu210023 China

We revisit the evaluations for the spacelike and timelike ρπ transition form factors Fρπ(Q2) and Gρπ(Q2) with the inclusion of the the next-to-leading order (NLO) QCD contributions in the framework of the kT factorization theorem. The infrared divergence is regularized by the transversal momentum carried by external valence quarks, and ultimately absorbed into the meson wave functions. In the region of Q2 6 2 GeV2, where PQCD factorization apporach applicable, the NLO contribution can bring no larger than 35% enhancement to the spacelike form factor Fρπ(Q2). For the timelike form factor derived under the kinematic exchanging symmetry, this contribution is also under control when the momentum transfer squared is large enough. We also prolong our prediction into the small Q2 region by taking the Lattice QCD results into account, and subsequently obtain the coupling gρπγ = Gρπ(0) = 0.596. Copyright © 2018, The Authors. All rights reserved.

关键词： Approximation theory

NLO twist-3 contributions to B→π form factors in kT factorization

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Physical Review D 2014年第9期89卷 094004-094004页

作者： Shan Cheng Ying-Ying Fan Xin Yu Cai-Dian Lü Zhen-Jun Xiao Department of Physics and Institute of Theoretical Physics Nanjing Normal University Nanjing Jiangsu 210023 People’s Republic of China Institute of High Energy Physics and Theoretical Physics Center for Science Facilities Chinese Academy of Sciences Beijing 100049 People’s Republic of China Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing 210023 People’s Republic of China

In this paper, we calculate the next-to-leading-order (NLO) twist-3 contribution to the form factors of B→π transitions by employing the kT factorization theorem. All the infrared divergences regulated by the logarithms ln(kiT2) cancel between those from the quark diagrams and from the effective diagrams for the initial B meson wave function and the final pion meson wave function. An infrared finite NLO hard kernel is, therefore, obtained, which confirms the application of the kT factorization theorem to the B meson semileptonic decays at the twist-3 level. From our analytical and numerical evaluations, we find that the NLO twist-3 contributions to the form factors f+,0(q2) of the B→π transition are similar in size but have an opposite sign with the NLO twist-2 contribution, which leads to a large cancellation between these two NLO parts. For the case of f+(0), for example, the 24% NLO twist-2 enhancement to the full LO prediction is largely canceled by the negative (about −17%) NLO twist-3 contribution, leaving a small and stable 7% enhancement to the full LO prediction in the whole range of 0≤q2≤12 GeV2. At the full NLO level, the perturbative QCD prediction is FB→π(0)=0.269−0.050+0.054. We also study the possible effects on the perturbative QCD predictions when different sets of the B meson and pion distribution amplitudes are used in the numerical evaluation.

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On semilinear Tricomi equations with critical exponents or in two space dimensions

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arXiv 2017年

作者： He, Daoyin Witt, Ingo Yin, Huicheng Department of Mathematics and IMS Nanjing University Nanjing210093 China Mathematical Institute University of Göttingen Bunsenstr. 3-5 GöttingenD-37073 Germany School of Mathematical Sciences Jiangsu Provincial Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing210023 China

This paper is a complement of our recent works on the semilinear Tricomi equations in [8] and [9]. For the semilinear Tricomi equation ∂t2u−t∆u = |u|p with initial data (u(0, ·), ∂tu(0, ·)) = (u0, u1), where t ≥ 0, x ∈ Rn (n ≥ 3), p > 1, and ui ∈ C0∞(Rn) (i = 0, 1), we have shown in [8] and [9] that there exists a critical exponent pcrit(n) > 1 such that the solution u, in general, blows up in finite time when 1 crit(n), and there is a global small solution for p > pcrit(n). In the present paper, firstly, we prove that the solution of ∂t2u − t∆u = |u|p will generally blow up for the critical exponent p = pcrit(n) and n ≥ 2, secondly, we establish the global existence of small data solution to ∂t2u − t∆u = |u|p for p > pcrit(n) and n = 2. Thus, we have given a systematic study on the blowup or global existence of small data solution u to the equation ∂t2u − t∆u = |u|p for n ≥ 2.35L70, 35L65, 35L67 Copyright © 2017, The Authors. All rights reserved.

关键词：

Double-heavy tetraquarks

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Physical Review D 2020年第1期101卷 014001-014001页

作者： Gang Yang Jialun Ping Jorge Segovia Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics Tsinghua University Beijing 100084 People’s Republic of China Department of Physics and Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing 210023 People’s Republic of China Departamento de Sistemas Físicos Químicos y Naturales Universidad Pablo de Olavide E-41013 Sevilla Spain

In the framework of the chiral quark model along with complex scaling range, we perform a dynamical study on the low-lying S-wave double-heavy tetraquark states (QQq¯q¯, Q=c, b and q=u, d) with an accurate computing approach, Gaussian expansion method. The meson-meson and diquark-antidiquark configurations within all possible color structures for spin-parity quantum numbers JP=0+, 1+, and 2+ and in the 0 and 1 isospin sectors are considered. Possible tightly bound and narrow resonance states are obtained for double-charm and double-bottom tetraquarks with IJP=01+, and these exotic states are also obtained in charm-bottom tetraquarks with 00+ and 01+ quantum numbers. Only a loosely bound state is found in charm-bottom tetraquarks of 02+ states. All of these bound states within meson-meson configurations are loosely bound whether in color-singlet channels or coupling to hidden-color ones. However, compact structures are available in diquark-antidiquark channels except for charm-bottom tetraquarks in 02+ states.

关键词： Hadron mixing Hadron-hadron interactions Quark mixing Quark model Heavy mesons Mass Parity Spin