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Dynamical thermalization of Frenkel-Kontorova model in the thermodynamic limit

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Physical Review E 2016年第2期93卷 022216-022216页

作者： Zhenjun Zhang Chunmei Tang Peiqing Tong College of Science Hohai University Nanjing Jiangsu 210098 People's Republic of China School of Physics Science and Technology Nanjing Normal University Nanjing Jiangsu 210023 People's Republic of China Jiangsu Provincial Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing Jiangsu 210023 People's Republic of China

We study numerically the process of dynamical thermalization in the Frenkel-Kontorova (FK) model with weak nonlinearity. The total energy has initially equidistributed among some of the lowest frequency linear modes. It is found that the energy transfers continuously to the high-frequency modes and finally evolves towards energy equipartition in the FK model. However, the metastable state, which was found in Fermi-Pasta-Ulam (FPU) model and φ4 model in a relatively short time scale, is not found in the FK model. We further perform a very accurate systematic study of the equipartition time Teq as functions of the particle number N, the nonlinear parameter β, and the energy density ɛ. In the thermodynamic limit, the dependence of Teq on β and ɛ is found to display a power law behavior: Teq∝βaɛb. The exponents a and b are numerically found to be approximately −2.0 and 1.43. This scaling law is also quite different from those of the FPU-β model and φ4 model.

关键词： Lattice dynamics Lattice models in statistical physics Lattice models in condensed matter

Heat conduction in one-dimensional aperiodic quantum Ising chains

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Physical Review E 2011年第3期83卷 031128-031128页

作者： Wenjuan Li Peiqing Tong Department of Physics and Institute of Theoretical Physics Nanjing Normal University Nanjing 210046 People’s Republic of China Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing 210046 People’s Republic of China

The heat conductivity of nonperiodic quantum Ising chains whose ends are connected with heat baths at different temperatures are studied numerically by solving the Lindblad master equation. The chains are subjected to a uniform transverse field h, while the exchange coupling Jm between the nearest-neighbor spins takes the two values JA and JB arranged in Fibonacci, generalized Fibonacci, Thue-Morse, and period-doubling sequences. We calculate the energy-density profile and energy current of the resulting nonequilibrium steady states to study the heat-conducting behavior of finite but large systems. Although these nonperiodic quantum Ising chains are integrable, it is clearly found that energy gradients exist in all chains and the energy currents appear to scale as the system size 〈Q〉~Nα. By increasing the ratio of couplings, the exponent α can be modulated from α>−1 to α<−1 corresponding to the nontrivial transition from the abnormal heat transport to the heat insulator. The influences of the temperature gradient and the magnetic field to heat conduction have also been discussed.

关键词： HEAT conduction ISING model EQUATIONS FIBONACCI sequence THERMAL conductivity

Topological properties and localization transition in a one-dimensional non-Hermitian lattice with a slowly varying potential

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Physical Review B 2022年第10期105卷 104201-104201页

作者： Siqing Li Mengyao Li Yi Gao Peiqing Tong Center for Quantum Transport and Thermal Energy Science Jiangsu Key Laboratory on Opto-Electronic Technology School of Physics and Technology Nanjing Normal University Nanjing 210023 China Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems School of Physics and Technology Nanjing Normal University Nanjing 210023 China

We explore the eigenenergy distribution, localization transition, and topological property of a one-dimensional non-Hermitian lattice with a slowly varying potential, which does not possess parity-time (PT) symmetry. We found that, in contrast to PT-symmetric systems whose eigenenergies can stay real until the PT-symmetry breaking point, the eigenenergies in the present system are fully complex and their distribution in the complex plane depends on the parameters. As non-Hermiticity is introduced into the system, also depending on the parameters, the eigenstates may show a crossover behavior from fully extended to fully localized as non-Hermiticity is increased, or there will be a sharp localization transition at finite non-Hermiticity. Nevertheless, this non-Hermitian system is proven to be topologically trivial, thus we conclude that in general non-Hermitian systems, the localization transition is not always of a topological nature.

关键词： Anderson localization Topological phase transition Non-Hermitean systems PT-symmetry

Reanalysis of the most strange dibaryon within constituent quark models

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arXiv 2019年

作者： Huang, Hongxia Zhu, Xinmei Ping, Jialun Department of Physics Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing210023 China Department of Physics Yangzhou University Yangzhou225009 China

The most strange dibaryon ΩΩ with quantum numbers S = −6, I = 0, and JP = 0+, 1−, 2+, 3− is reanalyzed in the framework of quark delocalization color screening model (QDCSM) and chiral quark model (ChQM). The ΩΩ dibaryon with JP = 0+ is bound, and the one with other quantum numbers JP = 1−, 2+, 3− are all unbound in our calculation. The low-energy scattering phase shifts, the scattering length, and the effective range of the ΩΩ dibaryon with JP = 0+ also support the existence of such strange dibaryon. This dibaryon is showed to be a shallow bound state in QDCSM, while the binding energy becomes much larger in the ChQM by including the effect of the hidden-color channel coupling. And the scalar nonet meson-exchange in the ChQM also provides more attraction for the ΩΩ system. Experimental search for such most strange dibaryon will provide much information for understanding the hadron-hadron interactions in different quark models. Copyright © 2019, The Authors. All rights reserved.

关键词： Quantum theory

Search for doubly-heavy dibaryons in the quark-delocalization color-screening model

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arXiv 2021年

作者： Xia, Zhuocheng Fan, Saijun Zhu, Xinmei Huang, Hongxia Ping, Jialun Department of Physics Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing210023 China Department of Physics Yangzhou University Yangzhou225009 China

We perform a systemical investigation of the low-lying doubly-heavy dibaryon systems with strange S = 0, isospin I = 0, 1, 2 and the angular momentum J = 0, 1, 2, 3 in the quark de- localization color screening model. We find the effect of channel-coupling cannot be neglected in the study of the multi-quark systems. Due to the heavy flavor symmetry, the results of the doubly- charm and doubly-bottom dibaryon systems are similar with each other. Both of them have three bound states, the quantum numbers of which are IJ = 00, IJ = 02 and IJ = 13, respectively. The energies are 4554 MeV, 4741 MeV, and 4969 MeV respectively for the doubly-charm systems and 11219 MeV, 11416 MeV, and 11633 MeV respectively for the doubly-bottom dibaryon systems. Besides, six resonance states are obtained, which are IJ = 00 NΞccand NΞbbwith resonance mass of 4716 MeV and 11411 MeV respectively, IJ = 11 NΞ∗ccand NΞ∗bbwith resonance mass of 4757 MeV and 11432 MeV respectively, and IJ = 12 ΣcΣ∗cand ΣbΣ∗bwith resonance mass of 4949 MeV and 11626 MeV respectively. All these heavy dibaryons are worth searching for on experiments, although it will be a challenging work. © 2021, CC BY.

关键词： Resonance

Is d∗(2380) a compact hexaquark state?

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arXiv 2023年

作者： Pan, Manying Zhu, Xinmei Ping, Jialun Department of Physics Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing210023 China Department of Physics Yangzhou University Yangzhou225009 China

The most fascinating dibaryon in the non-strange quark sector is d∗(2380), which was reported by WASA-at-COSY Collaboration and confirmed by A2@MAMI Collaboration. The reported mass and decay width are M ≈ 2.37 GeV, Γ ≈ 70 MeV and the quantum numbers are IJP = 03+. The structure of d∗(2380) is still in controversy. In the present calculation, the powerful method in few-body system, Gaussian Expansion Method (GEM) is employed to explore the structure of d∗(2380) in the framework of constituent quark models without assuming the presupposed structure. The results show that the radius of d∗(2380) is around 0.8 fm, it is a very compact object. Because of the compact structure, the color singlet-singlet component has a large overlap with the color octet-octet one, two colorless, large overlapped ∆s dominate the state is possible. Copyright © 2023, The Authors. All rights reserved.

关键词： Color

Quasi-two-body decays Bc → D(s)[ρ(770), ρ(1450), ρ(1700) →]ππ in the perturbative QCD factorization approach

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arXiv 2017年

作者： Ma, Ai-Jun Li, Ya Xiao, Zhen-Jun Department of Physics and Institute of Theoretical Physics Nanjing Normal University Nanjing Jiangsu210023 China Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing Jiangsu210023 China

In this paper, we studied the quasi-two-body Bc → D(s)[ρ(770), ρ(1450), ρ(1700) →]ππ decays by employing the perturbative QCD (PQCD) factorization approach. The two-pion distribution amplitudes φππ are applied to include the final-state interactions between the pion pair, while the time-like form factors Fπ(w2) associated with the P-wave resonant states ρ(770), ρ(1450) and ρ(1700) are extracted from the experimental data of the e+e-annihilation. We found that: (a) the PQCD predictions for the branching ratios of the quasi-two-body Bc → D(s)[ρ(770), ρ(1450), ρ(1700) →]ππ decays are in the order of 10-9 to 10-5 and the direct CP violations around (10 - 40)% in magnitude;(b) the two sets of the large hierarchy R1a,1b,1c and R2a,2b,2c for the ratios of the branching ratios of the considered decays are defined and can be understood in the PQCD factorization approach, while the self-consistency between the quasi-two-body and two-body framework for Bc → D(s)[ρ(770) →]ππ and Bc → D(s)ρ(770) decays are confirmed by our numerical results;(c) taking currently known B(ρ(1450) → ππ) and B(ρ(1700) → ππ) as input, we extracted the theoretical predictions for B(Bc → Dρ(1450)) and B(Bc → Dρ(1700)) from the PQCD predictions for the decay rates of the quasi-two-body decays Bc → D[ρ(1450), ρ(1700) →]ππ. All the PQCD predictions will be tested in the future experiments. Copyright © 2017, The Authors. All rights reserved.

关键词： Hadrons

Semileptonic decays B/Bs → (D(∗), Ds(∗))lνl in the PQCD approach with the lattice QCD input

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arXiv 2019年

作者： Hu, Xue-Qing Jin, Su-Ping Xiao, Zhen-Jun Department of Physics and Institute of Theoretical Physics Nanjing Normal University Nanjing Jiangsu210023 China Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing210023 China

In this paper, we studied the semileptonic B/Bs → (D(∗),Ds(∗))lνl decays in the framework of the standard model (SM), by employing the perturbative QCD (PQCD) factorization formalism combining with the lattice QCD inputs of the relevant transition form factors. We calculated the branching ratios B(B(s) → D((s∗))lνl) with l = (e,µ.τ), the ratios of the branching ratios R(D(∗)) and R(Ds(∗)) and other physical observables Pτ(D((s∗))), FL(D(∗s)) and AFB(τ). The "PQCD+Lattice" predictions for B(B → D(∗)lνl) and R(D(∗)) do agree well with those currently available experimental measurements within the errors. For the ratios R(Ds) and R(Ds∗), the"PQCD+Lattice" predictions agree well with other known predictions. For both Pτ(D∗) and FL(D∗), our theoretical predictions agree well with the measured values within errors. Our theoretical predictions about the considered semileptonic B/Bs decays could be tested in the near future LHCb and the Belle II experiments. Copyright © 2019, The Authors. All rights reserved.

关键词： Quantum theory

Study of Bs→ φ+-decays in the PQCD factorization approach with lattice QCD input

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arXiv 2020年

作者： Jin, Su-Ping Xiao, Zhen-Jun Department of Physics and Institute of Theoretical Physics Nanjing Normal University Jiangsu Nanjing210023 China Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing210023 China

In this paper, we studied systematically the semileptonic decays Bs→ φl+l-with l-= (e-, μ-, τ-) by using the perturbative QCD (PQCD) and the "PQCD+Lattice" factorization approach, respectively. We first evaluated all relevant form factors Fi(q2) in the low q2region using the PQCD approach, and we also took the available lattice QCD results at the high-q2region as additional input to improve the extrapolation of Fi(q2) from the low-q2region to the endpoint qmax2. We then calculated the branching ratios and many other physical observables: AFBl, FLφ, S3,4,7, A5,6,8,9and the clean angular observables P1,2,3and P'4,5,6,8. From our studies, we find the following points: (a) the PQCD and "PQCD+Lattice" predictions of B(Bs→ φμ+μ-) are about 7×10-7, which agree well with the LHCb measured values and the QCD sum rule prediction within still large errors;(b) we defined and calculated the ratios of the branching ratios Rφeμand Rφμτ;(c) the PQCD and "PQCD+Lattice" predictions of the longitudinal polarization FL, the CP averaged angular coefficients S3,4,7and the CP asymmetry angular coefficients A5,6,8,9, agree with the LHCb measurements in all considered bins within the still large experimental errors;and (d) for those currently still unknown observables Rφeμ,Rφμτ,AFBl, P1,2,3and P'4,5,6,8, we suggest LHCb and Belle-II Collaboration to measure them in their experiments. © 2020, CC BY.

关键词： Quantum theory