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Influence of weak disorder on the dynamical quantum phase transitions in the anisotropic XY chain

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Physical Review B 2020年第1期102卷 014207-014207页

作者： Kaiyuan Cao Wenwen Li Ming Zhong Peiqing Tong Department of Physics Institute of Theoretical Physics Nanjing Normal University Nanjing 210023 China Department of Physics Institute of Theoretical Physics Nanjing Normal University Nanjing 210023 China Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing 210023 China

We study the influence of disorder on the dynamical quantum phase transitions (DQPTs) in the transverse-field anisotropic XY chain after a sudden quench. The formulas to calculate the Loschmidt echo and Fisher zeros of the inhomogeneous XY chain are derived in real space. It is found that new DQPTs appear in the presence of weak disorder for the quenches across the Ising transition and two quantum phase transitions (Ising and anisotropic transitions). As the disorder strength increases, it's demonstrated that the Fisher zeros coalesce to regions on the imaginary axis in the thermodynamic limit. The DQPTs occur at the critical times corresponding to the boundaries of the Fisher zeros regions on the imaginary axis. However, for the quench across the anisotropic transition, the Fisher zeros regions appear even for the very weak disorder. Finally, for the quench within the same phase, the weak disorder is found having no effect on the DQPTs, but the DQPTs will be washed out in the presence of strong disorder.

关键词： Dynamical phase transitions Nonequilibrium statistical mechanics Quantum phase transitions 1-dimensional spin chains Disordered systems Lee-Yang & Fisher zeroes

On the global existence and stability of 3-D viscous cylindrical circulatory flows

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arXiv 2017年

作者： Yin, Huicheng Zhang, Lin School of Mathematical Sciences Jiangsu Provincial Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing210023 China Department of Mathematics and IMS Nanjing University Nanjing210093 China

In this paper, we are concerned with the global existence and stability of a 3-D perturbed viscous circulatory flow around an infinite long cylinder. This flow is described by 3-D compressible Navier-Stokes equations. By introducing some suitably weighted energy spaces and establishing a priori estimates, we show that the 3-D cylindrical symmetric circulatory flow is globally stable in time when the corresponding initial states are perturbed suitably small. Copyright © 2017, The Authors. All rights reserved.

关键词： Viscous flow

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

Theoretical study of a d* resonance in the coupled 3D3−3G3 partial waves of nucleon-nucleon scattering

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Physical Review C 2014年第6期90卷 064003-064003页

作者： Hongxia Huang Jialun Ping Chengrong Deng Fan Wang Department of Physics and Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing 210023 China School of Mathematics and Physics Chongqing Jiaotong University Chongqing 400074 China Department of Physics Nanjing University Nanjing 210093 China

We calculated the phase shifts of the coupled 3D3−3G3 partial waves of nucleon-nucleon scattering taking into account the 7S3 Δ−Δ channel coupling in the framework of two constituent quark models: the quark delocalization color screening model and the chiral quark model. Our results show that there is a resonance from 7S3ΔΔ coupling to the 3D3NN and 3G3NN partial waves in both of these two models, which is consistent with the d* resonance observed by WASA-at-COSY collaboration. The resonance structure in the 3D3NN partial wave is remarkable, whereas in the 3G3NN phase shifts there is only a small bump around the resonance energy. This result is in agreement with the recent experimental results of WASA-at-COSY Collaboration.

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Quasi-two-body decays B(s) → Pp'(1450), Pp'(1700) Pππ in the perturbative QCD approach

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arXiv 2017年

作者： Li, Ya Ma, Ai-Jun Wang, Wen-Fei Xiao, Zhen-Jun Institute of Theoretical Physics Shanxi University Taiyuan Shanxi030006 Department of Physics Institute of Theoretical Physics Nanjing Normal University Nanjing Jiangsu210023 Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing Jiangsu210023

In this work, we calculate the CP-averaged branching ratios and direct CP-violating asymmetries of the quasi-two-body decays B(s) → P'(1450), Pp'(1700) → Pππ by employing the perturbative QCD (PQCD) factorization approach, where P is a light pseudoscalar meson K, π, n, and n'. The considered decay modes are studied in the quasi-two-body framework by parametrizing the two-pion distribution amplitude P ππ. The P-wave timelike form factor Fπ in the resonant regions associated with the pp'(1450) and p'(1700) is estimated based on available experimental data. The PQCD predictions for the CP-averaged branching ratios of the decays B(s) → Pp'(1450) pp'(1700) → Pππ are in the order of 10-7-10-9. The branching ratios of the two-body decays B(s) → Pp'(1450), Pp'(1700) are extracted from the corresponding quasi-twobody decay modes. The whole pattern of the squared pion form factor |Fπ|2 measured by BABAR Collaboration could also be understood based on our studies. The PQCD predictions in this work will be tested by the precise data from the LHCb and the future Belle II experiments. Copyright © 2017, The Authors. All rights reserved.

关键词： Hadrons

Hidden-bottom pentaquarks

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arXiv 2018年

作者： Yang, Gang Ping, Jialun Segovia, Jorge Department of Physics State Key Laboratory of Low-Dimensional Quantum Physics Tsinghua University Beijing100084 China Department of Physics Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing210023 China E-08193 Spain

The LHCb Collaboration has recently reported strong evidences of the existence of pentaquark states in the hidden-charm baryon sector, the so-called Pc(4380)+and Pc(4450)+signals. Five-quark bound states in the hidden-charm sector were explored by us using, for the quark-quark interaction, a chiral quark model which successfully explains meson and baryon phenomenology, from the light to the heavy quark sector. We extend herein such study but to the hidden-bottom pentaquark sector, analyzing possible bound-states with spin-parity quantum numbers JP= 1/2±, 3/2±and 5/2±, and in the 1/2 and 3/2 isospin sectors. We do not find positive parity hidden-bottom pentaquark states;however, several candidates with negative parity are found with dominant baryon-meson structures Σ(∗)bB(∗). The calculated distances among any pair of quarks within the bound-state reflect that molecular-type bound-states are favored when only color-singlet configurations are considered in the coupled-channels calculation whereas compact pentaquarks, which are also deeply bound, can be found when hidden-color configurations are added. Finally, our findings resemble the ones found in the hidden-charm sector but, as expected, we find in the hidden-bottom sector larger binding energies and bigger contributions of the hidden-color configurations. Copyright © 2018, The Authors. All rights reserved.

关键词： Hadrons

Exploring Dynamical Phase Transitions in the XY Chain through Linear Quench: Early and Long-term Perspectives

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arXiv 2024年

作者： Cao, Kaiyuan Tong, Peiqing Zhejiang Lab Hangzhou311100 China Department of Physics Institute of Theoretical Physics Nanjing Normal University Nanjing210023 China Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing210023 China

We investigate the nonequilibrium dynamics induced by a finite-time linear quench in the XY chain. Initially, we examine the dynamical quantum phase transition, characterized by the nonanalytic behavior of the Loschmidt amplitude. We find distinct behaviors of DQPTs during and following the ramp. Following the ramp, the ramp crossing the critical point hc is the sufficient condition for the occurrence of DQPT, but it is not during the ramp. Through AIA approximation analysis, we establish that adequate distancing from the critical point is crucial for DQPT manifestation during the ramp, elucidating the absence of DQPT as the ramp gets faster. Additionally, we explore another type of dynamical phase transition, describing the long-term relaxation behavior of the order parameter. Our finding indicates that the asymptotic behavior of the time-dependent part induced by the linear quench is equivalent to that following a sudden quench, i.e., time-dependent part exhibits power-law decays of ∼ t−3/2 and ∼ t−1/2 for the ramp to the commensurate and incommensurate phases, respectively. Moreover, we also delve into the steady part, which showcases nonanalytic singularities at the critical point. Copyright © 2024, The Authors. All rights reserved.

关键词： Phase transitions

Quantum Phase Transitions in the Alternating Xy Chain with Three-Site Interactions

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SSRN

SSRN 2024年

作者： Cao, Kaiyuan Fu, Hao Liu, Xue Zhong, Ming Tong, Peiqing Zhejiang Lab Hangzhou311100 China Department of Physics Institute of Theoretical Physics Nanjing Normal University Nanjing210023 China Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing210023 China

We investigate the quantum phase transition in the alternating XY chain with the XZX+YZY type of three-spin interactions. We present the exact solution derived by means of the Jordan-Wigner transformation and study the average magnetization, spin correlations, and von Neumann entropy to establish the phase diagram. The phase diagram consists of the ferromagnetic phases, the paramagnetic phases, and the phase with weak magnetization (WM). By examining the nearest-neighbor transverse spin correlation, we probe that in the WM phase, the spins within a supercell generate a cluster with a small total spin, but between the nearest-neighbor supercells are distributed randomly. Especially for the dimerized limit case, the spins within a supercell tend to point to opposite directions of the transverse field. In addition, we also investigate the influence of the three-site interaction, and find that the WM phase is absent as the strength of the three-site interaction increases. © 2024, The Authors. All rights reserved.

关键词： Magnetization

Quantum phase transitions in the alternating XY chain with three-site interactions

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arXiv 2024年

关键词： Magnetization