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学者姓名：胡进
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Abstract ：
We address the linear-mode analysis performed near an equilibrium configuration in the fluid rest frame with a dynamical magnetic field perturbed on a constant configuration. We develop a simple and general algorithm for an analytic solution search that works on an order-by-order basis in the derivative expansion. This method can be applied to general sets of hydrodynamic equations. Applying our method to the firstorder relativistic magnetohydrodynamics, we demonstrate that the method finds a complete set of solutions. We obtain two sets of analytic solutions for the four and two coupled modes with seven dissipative transport coefficients. The former set has been missing in the literature for a long time due to the difficulties originating from coupled degrees of freedom and strong anisotropy provided by a magnetic field. The newly developed method resolves these difficulties. We also find that the small-momentum expansions of the solutions break down when the momentum direction is nearly perpendicular to an equilibrium magnetic field due to the presence of another small quantity, that is, a trigonometric function representing the anisotropy. We elaborate on the angle dependence of the solutions and provide alternative series representations that work near the right angle. This identifies the origin of a discrepancy found in recent works. Finally, we discuss the issues of causality and stability based on our analytic solutions and recent developments in the literature.
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| GB/T 7714 | Fang, Zhe , Hattori, Koichi , Hu, Jin . Analytic solutions for the linearized first-order magnetohydrodynamics and implications for causality and stability [J]. | PHYSICAL REVIEW D , 2024 , 110 (5) . |
| MLA | Fang, Zhe 等. "Analytic solutions for the linearized first-order magnetohydrodynamics and implications for causality and stability" . | PHYSICAL REVIEW D 110 . 5 (2024) . |
| APA | Fang, Zhe , Hattori, Koichi , Hu, Jin . Analytic solutions for the linearized first-order magnetohydrodynamics and implications for causality and stability . | PHYSICAL REVIEW D , 2024 , 110 (5) . |
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Background: Nuclear masses are of fundamental importance in both nuclear physics and astrophysics, and the masses for most neutron-rich exotic nuclei are still beyond the experimental capability. The relativistic continuum Hartree-Bogoliubov (RCHB) theory has achieved great successes in the studies of both stable and exotic nuclei. The mass table based on the RCHB theory has been constructed with the assumption of spherical symmetry [Xia et al., At. Data Nucl. Data Tables 121, 1 (2018)]. The upgraded version including deformation effects based on the deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc) is under construction, and the part for even-even nuclei has been finished [Zhang et al., At. Data Nucl. Data Tables 144, 101488 (2022)]. The kernel ridge regression (KRR) approach is a useful machine-learning approach in refining nuclear mass prediction, and is found to be reliable in avoiding the risk of worsening predictions at large extrapolation distance [Wu and Zhao, Phys. Rev. C 101, 051301(R) (2020)]. Purpose: The aim of this work is to combine the RCHB mass model and the KRR approach to construct a high-precision and reliable nuclear mass model describing both stable and weakly bound neutron-rich exotic nuclei. Another purpose is to utilize the masses of even-even nuclei from the DRHBc theory to validate the performance of the KRR approach. Method: The KRR approach is employed to refine the RCHB mass model by learning and representing the mass residual of the RCHB mass model with the experimental data. The leave-one-out cross-validation is applied to determine the hyperparameters in the KRR approach. The DRHBc mass model for even-even nuclei is employed to help to analyze the physical effects included in the KRR corrections and examine the KRR extrapolations. Results: The refined RCHB mass model with KRR corrections can achieve an accuracy of root-mean-square deviation 385 keV from the experimental masses. The major contributions contained in the KRR corrections are found to be the deformation effects. The KRR corrections also contain some residual deformation effects and some other effects beyond the scope of the DRHBc theory. The extrapolation of the KRR approach in refining the RCHB predictions is found to be very reliable. Conclusions: A mass model benefiting from the RCHB model with continuum effects properly treated and the KRR approach is constructed. This model is demonstrated to be accurate in reproducing the masses of experimentally known nuclei and reliable in extrapolating to the experimentally unknown neutron-rich regions.
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| GB/T 7714 | Wu, X. H. , Pan, C. , Zhang, K. Y. et al. Nuclear mass predictions of the relativistic continuum Hartree-Bogoliubov theory with the kernel ridge regression [J]. | PHYSICAL REVIEW C , 2024 , 109 (2) . |
| MLA | Wu, X. H. et al. "Nuclear mass predictions of the relativistic continuum Hartree-Bogoliubov theory with the kernel ridge regression" . | PHYSICAL REVIEW C 109 . 2 (2024) . |
| APA | Wu, X. H. , Pan, C. , Zhang, K. Y. , Hu, J. . Nuclear mass predictions of the relativistic continuum Hartree-Bogoliubov theory with the kernel ridge regression . | PHYSICAL REVIEW C , 2024 , 109 (2) . |
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We systematically derive the quantum generalized nonlinear Langevin equation using Morozov's allowing for the inclusion of nonlinear interactions among macroscopic modes. Additionally, we obtain the quantum generalized Fokker-Planck equation within the Heisenberg picture, which is consistent with Morozov's original formulation. These equations are fundamentally significant in nonequilibrium statistical physics, particularly in scenarios characterized by enhanced fluctuations, such as anomalous transport phenomena near critical points. The quantum nature of the derived generalized Langevin and Fokker-Planck equations is anticipated to provide a more detailed description than their classical equivalents. Specifically, the noise kernel in the quantum generalized Langevin equation is multiplicative, which broadens the applicability beyond Gaussian approximations. Given specific interactions, these equations are expected to be instrumental in investigating critical transport phenomena.
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| GB/T 7714 | Hu, Jin . Generalized nonlinear Langevin equation from quantum nonlinear projection operator [J]. | PHYSICAL REVIEW D , 2024 , 110 (5) . |
| MLA | Hu, Jin . "Generalized nonlinear Langevin equation from quantum nonlinear projection operator" . | PHYSICAL REVIEW D 110 . 5 (2024) . |
| APA | Hu, Jin . Generalized nonlinear Langevin equation from quantum nonlinear projection operator . | PHYSICAL REVIEW D , 2024 , 110 (5) . |
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