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QQs¯s¯ tetraquarks in the chiral quark model

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arXiv 2020年

The low-lying S-wave QQs¯s¯ (Q = c, b) tetraquark states with IJP = 00+, 01+ and 02+ are systematically investigated in the framework of complex scaling range of chiral quark model. Every structure including meson-meson, diquark-antidiquark and K-type configurations, and all possible color channels in four-body sector are considered by means of a commonly extended variational approach, Gaussian expansion method. Several narrow and wide resonance states are obtained for ccs¯s¯ and bbs¯s¯ tetraquarks with IJP = 00+ and 02+. Meanwhile, narrow resonances for cbs¯s¯ tetraquarks are also found in IJP = 00+, 01+ and 02+ states. These results confirm the possibility of finding hadronic molecules with masses ∼ 0.6 GeV above the noninteracting hadron-hadron thresholds. Copyright © 2020, The Authors. All rights reserved.

关键词： Hadrons

Multi-view adaptive fusion network for 3D object detection

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arXiv 2020年

作者： Wang, Guojun Tian, Bin Zhang, Yachen Chen, Long Cao, Dongpu Wu, Jian State Key Laboratory of Automotive Simulation and Control Jilin University Changchun130022 China State Key Laboratory of Management and Control for Complex Systems Institute of Automation Chinese Academy of Sciences School of Artificial Intelligence University of Chinese Academy of Sciences Beijing100190 China School of Data and Computer Science Sun Yat-Sen University Guangzhou510275 China Lab University of Waterloo Canada College of Automotive Engineering Jilin University China

3D object detection based on LiDAR-camera fusion is becoming an emerging research theme for autonomous driving. However, it has been surprisingly difficult to effectively fuse both modalities without information loss and interference. To solve this issue, we propose a single-stage multi-view fusion framework that takes LiDAR Birds-Eye View, LiDAR Range View and Camera View images as inputs for 3D object detection. To effectively fuse multi-view features, we propose an Attentive Pointwise Fusion (APF) module to estimate the importance of the three sources with attention mechanisms which can achieve adaptive fusion of multi-view features in a pointwise manner. Besides, an Attentive Pointwise Weighting (APW) module is designed to help the network learn structure information and point feature importance with two extra tasks: foreground classification and center regression, and the predicted foreground probability will be used to reweight the point features. We design an end-to-end learnable network named MVAF-Net to integrate these two components. Our evaluations conducted on the KITTI 3D object detection datasets demonstrate that the proposed APF and APW module offer significant performance gain and that the proposed MVAF-Net achieves state-of-the-art performance in the KITTI benchmark. Copyright © 2020, The Authors. All rights reserved.

关键词： Object recognition

Triply charm and bottom tetraquarks in a constituent quark model

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arXiv 2024年

Singly, doubly and fully charmed tetraquark candidates, e.g., Tcs¯(2900), Tcc+(3875) and X(6900) have been recently reported by the LHCb collaboration. Therefore, it is timely to implement a theoretical investigation on triply heavy tetraquark systems;herein, the S-wave triply charm and bottom tetraquarks, Q¯Qq¯Q (q = u, d, s;Q = c, b), with spin-parity JP = 0+, 1+ and 2+, isospin I = 0 and 1/2, are systematically studied in a constituent quark model. Besides, all tetraquark configurations, i.e. meson-meson, diquark-antidiquark and K-type arrangements, along with any allowed color structure, are comprehensively considered. The Gaussian expansion method (GEM), in combination with the complex-scaling method (CSM), which is quite ingenious in dealing with either bound or resonances, is the approach adopted in solving the complex scaled Schrödinger equation. This theoretical framework has already been applied in various tetra- and penta-quark systems. In a fully coupled-channel calculation within the GEM+CSM, narrow resonances are found in each I(JP) channel of the charm and bottom sector. In particular, triply charm and bottom tetraquark resonances are obtained in 5.6 − 5.9 GeV and 15.3 − 15.7 GeV, respectively. We provide also some insights of the compositeness of these exotic states, such as the inner quark distance, magnetic moment and dominant wave function component. All this may help to distinguish them in future high energy nuclear and particle experiments. Copyright © 2024, The Authors. All rights reserved.

关键词： Germanium alloys

The q¯qs¯Q (q = u, d;Q = c, b) tetraquark system in a chiral quark model

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arXiv 2023年

Inspired by the experimentally reported Tcs¯(2900) exotic states, the S-wave q¯qs¯Q (q = u, d;Q = c, b) tetraquarks, with spin-parity JP = 0+, 1+ and 2+, in both isoscalar and isovector sectors are systematically studied in a chiral quark model. The meson-meson, diquark-antidiquark and K-type arrangements of quarks, along with all possible color wave functions, are comprehensively considered. The four-body system is solved by means of a highly efficient computational approach, the Gaussian expansion method, along with a complex-scaling formulation of the problem to disentangle bound, resonance and scattering states. This theoretical framework has already been successfully applied in various tetra- and penta-quark systems. In the complete coupled-channel case, and within the complex-range formulation, several narrow resonances of q¯qs¯c and q¯qs¯b systems are obtained in each allowed I(JP)-channels. Particularly, the Tcs¯(2900) is well identified as a I(JP) = 1(0+) q¯qs¯c tetraquark state with a dominant molecular structure. Meanwhile, more resonances in q¯qs¯c and q¯qs¯b systems are also obtained within the energy regions 2.4 − 3.4 GeV and 5.7 − 6.7 GeV, respectively. The predicted exotic states, which are an indication of a richer color structure when going towards multiquark systems beyond mesons and baryons, are expected to be confirmed in future high-energy particle and nuclear experiments. Copyright © 2023, The Authors. All rights reserved.

关键词： Germanium alloys

Fully-charm and -bottom pentaquarks in a Lattice-QCD inspired quark model

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arXiv 2022年

The fully-charm and -bottom pentaquarks, i.e. ccccc¯ and bbbb¯b, with spin-parity quantum numbers JP = 1/2− , 3/2− and 5/2−, are investigated within a Lattice-QCD inspired quark model, which has already successfully described the recently announced fully-charm tetraquark candidate X(6900), and has also predicted several other fully-heavy tetraquarks. A powerful computational technique, based on the Gaussian expansion method combined with a complex-scaling range approach, is employed to predict, and distinguish, bound, resonance and scattering states of the mentioned five-body system. Both baryon-meson and diquark-diquark-antiquark configurations, along with all of their possible color channels are comprehensively considered. Narrow resonances are obtained in each spin-parity channel for the fully-charm and -bottom systems. Moreover, most of them seems to be compact multiquarks whose wave-functions are dominated by either hidden-color baryon-meson or diquark-diquark-antiquark structure, or by the coupling between them. Copyright © 2022, The Authors. All rights reserved.

关键词： Hadrons

Dynamical relaxation behavior of extended XY chain with gapless phase following a quantum quench

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arXiv 2023年

作者： Cao, Kaiyuan Hu, Yayun Tong, Peiqing Yang, Guangwen 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 Department of Computer Science and Technology Tsinghua University Haidian District Beijing100084 China

We investigate the dynamical relaxation behavior of the two-point correlation in extended XY models with a gapless phase after quenches from various initial states. Specifically, we study the XY chain with gapless phase induced by the additional interactions: Dzyaloshinskii-Moriya interaction and XZY-YZX type of three-site interaction. When quenching from the gapped phase, we observe that the additional interactions have no effect on the relaxation behavior. The relaxation behavior is δCmn(t) ∼ t−3/2 and ∼ t−1/2 for the quench to the commensurate phase and the incommensurate phase, respectively. However, when quenching from the gapless phase, we demonstrate that the scaling behavior of δCmn(t) is changed to ∼ t−1 for the quench to the commensurate phase, and the decay of δCmn(t) follows ∼ t−1 or ∼ t−1/2 for the quench to the incommensurate phase depending on the parameters of pre-quench Hamiltonian. We also establish the dynamical phase diagrams based on the dynamical relaxation behavior of δCmn(t) in the extended XY models. Copyright © 2023, The Authors. All rights reserved.

关键词： Quenching

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

Synthesizing and controlling helical indirect exchange interactions out of equilibrium

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Physical Review B 2018年第18期98卷 184426-184426页

作者： Tingting Liu Jie Ren Peiqing Tong Department of Physics and Institute of Theoretical Physics Nanjing Normal University Nanjing 210023 P. R. China Center for Phononics and Thermal Energy Science China-EU Joint Center for Nanophononics Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology School of Physics Science and Engineering Tongji University Shanghai 200092 P. R. China Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing 210023 P. R. China

We study the nonequilibrium effects of spin and/or electric currents on the helical indirect exchange interactions of local spins that embedded in general open electronic systems. Especially, besides the synthesized anisotropic Heisenberg interactions, we find that the synthetic helical indirect exchange interactions possess two parts: antisymmetric (Dzyaloshinskii-Moriya interaction) and symmetric (Kaplan-Shekhtman-Entin-Wohlman-Aharony interaction), which are all formulated in terms of Keldysh nonequilibrium Green's functions. The presence of either spin-orbit coupling or spin polarized currents alone is able to synthesize and control the antisymmetric Dzyaloshinskii-Moriya exchange interactions, as the same direction as spin splitting. However, the appearance of symmetric Kaplan-Shekhtman-Entin-Wohlman-Aharony interactions requires both, i.e., the spin-orbit coupling and spin polarized currents with different splitting directions. Our results show the detailed scheme of controlling the sign, magnitude, and direction of indirect Dzyaloshinskii-Moriya vectors and Kaplan-Shekhtman-Entin-Wohlman-Aharony interactions at nonequilibrium in open quantum devices.

关键词： Dzyaloshinskii-Moriya interaction Exchange interaction Open quantum systems RKKY interaction Rashba coupling

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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