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Structure of pentaquarks Pc+ in the chiral quark model

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Physical Review D 2017年第1期95卷 014010-014010页

作者： Gang Yang Jialun Ping Fan Wang 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 Department of Physics Nanjing University Nanjing 210093 People’s Republic of China

The recent experimental results of the LHCb Collaboration suggested the existence of pentaquark states with a charmonium. To understand the structure of the states, a dynamical calculation of 5-quark systems with quantum numbers IJP=12(12)±, 12(32)± and 12(52)± is performed in the framework of the chiral quark model with the help of the Gaussian expansion method. The results show that there are several negative parity resonance states while all of the positive parity states are the scattering states. The Pc(4380) state is suggested to be the pentaquark state of Σc*D¯. Although the energy of ΣcD¯* is very close to the mass of Pc(4450), the inconsistent parity prevents the assignment. The calculated distances between quarks confirm the molecular nature of the states.

关键词： Hadron-hadron interactions Quark model Exotic baryons

Dynamical quantum phase transition in quantum spin chains with gapless phases

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arXiv 2021年

作者： Cao, Kaiyuan Ming, Zhong Tong, Peiqing 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

The dynamical quantum phase transitions (DQPTs) in quantum spin chains with gapless phases after a sudden quench are studied. We mainly consider the general systems with asymmetrical quasiparticle excitation spectra and obtain the general expression of the Loschmidt echo as well as the general conditions for the occurrence of DQPTs. As two examples, we study the DQPTs in the XY chains with Dzyaloshinskii-Moriya interaction and XZY-YZX type of three-site interaction. It's found that the DQPTs may not occur in the quench across the quantum phase transitions regardless of whether the quench is from the gapless phase to gapped phase or from the gapped phase to gapless phase. This is different from the DQPTs in the case of quench from the gapped phase to gapped phase, in which the DQPTs will always appear. Besides, we also analyze the different reasons for the absence of DQPTs in the quench from the gapless phase and the gapped phase. © 2021, CC BY.

关键词： Phase transitions

Further study of the NΩ dibaryon within constituent quark models

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Physical Review C 2015年第6期92卷 065202-065202页

作者： Hongxia Huang Jialun Ping Fan Wang 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 Department of Physics Nanjing University Nanjing 210093 People's Republic of China

Inspired by the discovery of the dibaryon d* and the experimental search of NΩ dibaryon with the STAR data, we study the strange dibaryon NΩ further in the framework of the quark delocalization color screening model and the chiral quark model. We have shown NΩ is a narrow resonance in ΛΞ D-wave scattering before. However, the Λ−Ξ scattering data analysis is quite complicated. Here we calculate the low-energy NΩ scattering phase shifts, scattering length, effective range, and binding energy to provide another approach of STAR data analysis. Our results show there exists an NΩ “bound” state, which can be observed by the N−Ω correlation analysis with RHIC and LHC data, or by the new developed automatic scanning system at J-PARC. In addition, we also find that the hidden-color channel coupling is important for the NΩ system to develop intermediate-range attraction.

关键词： DIBARYON QUARK models PHASE shift (Nuclear physics) QUANTUM chromodynamics QUARK-gluon plasma

The effects of KSEA interaction on the ground-state properties of spin chains in a transverse field

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arXiv 2019年

作者： Fu, Hao Zhong, Ming Tong, Peiqing 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

The effects of symmetric helical interaction which is called the Kaplan, Shekhtman, Entin-Wohlman, and Aharony (KSEA) interaction on the ground-state properties of three kinds of spin chains in a transverse field have been studied by means of correlation functions and chiral order parameter. We find that the anisotropic transition of XY chain in a transverse field (XY TF) disappears because of the KSEA interaction. For the other two chains, we find that the regions of gapless chiral phases in the parameter space induced by the DM or XZY -Y ZX type of three-site interaction are decreased gradually with increase of the strength of KSEA interaction. When it is larger than the coefficient of DM or XZY - Y ZX type of three-site interaction, the gapless chiral phases also disappear. Copyright © 2019, The Authors. All rights reserved.

关键词： Spin dynamics

B→ππ decays and effects of the next-to-leading order contributions

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Physical Review D 2014年第1期90卷 014029-014029页

作者： Ya-Lan Zhang Xue-Yan Liu Ying-Ying Fan Shan Cheng Zhen-Jun Xiao Department of Physics and Institute of Theoretical Physics Nanjing Normal University Nanjing Jiangsu 210023 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 perform a systematic study for the three B→(π+π−,π+π0,π0π0) decays in the perturbative QCD (pQCD) factorization approach with the inclusion of all currently known next-to-leading order (NLO) contributions from various sources. We found that (a) for the CP-averaged decay rates Br(B0→π+π−) and Br(B+→π+π0), the NLO pQCD predictions agree with the data within one standard deviation; (b) for Br(B0→π0π0), however, although the NLO contributions can provide a ∼100% enhancement to the leading-order (LO) result, it is still not large enough to interpret the data; and (c) for the CP-violating asymmetries of B0→π+π− decay, the NLO pQCD predictions for the central values of Aππ and Sππ have the same sign as the data but are still smaller in magnitude than the measured values. We also examined the relative strength of the LO and NLO contributions from different sources.

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Influences of weak disorder on dynamical quantum phase transitions of anisotropic XY chain

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arXiv 2019年

作者： Cao, Kaiyuan Li, Wenwen Zhong, Ming Tong, Peiqing 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

In this paper, the effects of disorder on the dynamical quantum phase transitions (DQPTs) in the transverse-field anisotropic XY chain are studied by numerically calculating the Loschmidt echo after quench. We obtain the formula for calculating the Loschmidt echo of the inhomogeneous system in real space. By comparing the results with that of the homogeneous chain, we find that when the quench crosses the Ising transition, the small disorder will cause a new critical point. As the disorder increases, more critical points of the DQPTs will occur, constituting a critical region. In the quench across the anisotropic transition, the disorder will cause a critical region near the critical point, and the width of the critical region increases by the disordered strength. In the case of quench passing through two critical lines, the small disorder leads to the system to have three additional critical points. When the quench is in the ferromagnetic phase, the large disorder causes the two critical points of the homogeneous case to become a critical region. And for the quench in the paramagnetic phase, the DQPTs will disappear for large disorder. Copyright © 2019, The Authors. All rights reserved.

关键词： Phase transitions

The global existence and large time behavior of smooth compressible fluid in an infinitely expanding ball, III: The 3-D Boltzmann equation

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arXiv 2017年

作者： Yin, Huicheng Zhao, Wenbin 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

This paper is a continuation of the works in [34] and [36], where the authors have established the global existence of smooth compressible flows in infinitely expanding balls for inviscid gases and viscid gases, respectively. In this paper, we are concerned with the global existence and large time behavior of compressible Boltzmann gases in an infinitely expanding ball. Such a problem is one of the interesting models in studying the theory of global smooth solutions to multidimensional compressible gases with time dependent boundaries and vacuum states at infinite time. Due to the conservation of mass, the fluid in the expanding ball becomes rarefied and eventually tends to a vacuum state meanwhile there are no appearances of vacuum domains in any part of the expansive ball, which is easily observed in finite time. In the present paper, we will confirm this physical phenomenon for the Boltzmann equation by obtaining the exact lower and upper bound on the macroscopic density function. Copyright © 2017, The Authors. All rights reserved.

关键词： Boltzmann equation

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