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reflection and transmission properties of a finite-length electron plasma grating

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Matter and radiation at Extremes 2022年第5期7卷 17-28页

作者： G.Lehmann K.H.Spatschek institut für theoretische physik I Heinrich-Heine-Universität DüsseldorfD-40225 DüsseldorfGermany

Considered here is a plasma grating generated by two counterpropagating short laser pulses. Because of the shortness of the laser pulses, theplasma dynamics are determined by only electrons, which respond to the ponderomotive pressure generated by the interacting laser fields.An electron grating cannot exist for longer than the inverse ion plasma frequency, and so because of the limited time of the ponderomotivepressure, both the life time and spatial extent of an electron grating are finite. When one of the short laser pulses is circularly polarized(propagating in the x direction with electric field vectors in the yz plane) and the other is linearly y-polarized, the electron grating is producedby the y components. Meanwhile, the z component is partially reflected, and only a fraction of it is transmitted. Thus, the finite plasmagrating can either alter the polarization of the yz-polarized pulse or act as a pulse splitter. The present paper is focused on the reflection andtransmission rates. The action of the density grating on the z component cannot be explained by the Bloch wave theory for infinite crystals,and instead a theory is developed based on four-wave mixing, which explains the transmission and reflection of the z component wheninteracting with a grating of finite extent.

关键词： polarization finite polarized

Quantum Impurity Models with Coupled Cluster Method

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Communications in Theoretical Physics 2010年第9期54卷 509-517页

作者： Clive Emary Tobias Brandes institut für theoretische physik

我们与联合的簇方法调查安德森单身者杂质模型(有限库仑杂质排斥) 的地面状态性质。我们认为不同 CCM 是引用状态和近似计划并且为完整的交往模型与准确格林非交往的模型的函数结果并且与 BrillouinWigner 不安理论做比较。我们的结果... 详细信息

我们与联合的簇方法调查安德森单身者杂质模型(有限库仑杂质排斥) 的地面状态性质。我们认为不同 CCM 是引用状态和近似计划并且为完整的交往模型与准确格林非交往的模型的函数结果并且与 BrillouinWigner 不安理论做比较。我们的结果证明联合的簇技术很好被适合到量杂质问题。

关键词：相互作用模型耦合簇方法杂质量子基态性质格林函数摄动理论交互模型

Millimeter gap contrast as a probe for turbulence level in protoplanetary disks

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Science China(Physics,Mechanics & Astronomy) 2022年第12期65卷 131-144页

作者： Yao Liu Gesa H.-M.Bertrang Mario flock Giovanni P.rosotti Ewine f.van Dishoeck Yann Boehler Stefano facchini Can Cui Sebastian Wolf Min fang Max-Planck-institut für Extraterrestrische physik Garching85748Germany Purple Mountain Observatory&Key Laboratory for radio Astronomy Chinese Academy of SciencesNanjing210023China Max-Planck-institut für Astronomie HeidelbergD-69117Germany Leiden Observatory Leiden UniversityLeidenNL-2300the Netherlands School of Physics and Astronomy University of LeicesterLeicesterLE17RHUK UniversitéGrenoble Alpes French National Centre for Scientific ResearchInstitute for Planetary Sciences and AstrophysicsGrenobleGrenobleF-38000France European Southern Observatory Garching85748Germany Department of Applied Mathematics and Theoretical Physics University of CambridgeCentre for Mathematical SciencesCambridgeCB3 OWAUK institut für theoretische physik und astrophysik Christian-Albrechts-Universität zu kielKiel24118Germany

Turbulent motions are believed to regulate angular momentum transport and influence dust evolution in protoplanetary disks.Measuring the strength of turbulence is challenging through gas line observations because of the requirement for high spatial and spectral resolution data,and an exquisite determination of the temperature.In this work,taking the well-known HD 163296 disk as an example,we investigated the contrast of gaps identified in high angular resolution continuum images as a probe for the level of turbulence.With self-consistent radiative transfer models,we simultaneously analyzed the radial brightness profiles along the disk major and minor axes,and the azimuthal brightness profiles of the B67 and B100 rings.By fitting all the gap contrasts measured from these profiles,we constrained the gas-to-dust scale height ratioΛto be 3.0^(+0.3)_(−0.8),1.2^(+0.1)_(−0.1),and≥6.5 for the D48,B67,and B100 regions,respectively.The varying gas-to-dust scale height ratios indicate that the degree of dust settling changes with radius.The inferred values forΛtranslate into a turbulence level of α_(turb)regions,which is consistent with previous upper limits set by gas line observations.However,turbulent motions in the B67 ring are strong with α_(turb)∼1.2×10^(−2).Due to the degeneracy betweenΛand the depth of dust surface density drops,the turbulence strength in the D86 gap region is not constrained.

关键词： protoplanetary disks radiative transfer planet formation

Statistical learning of engineered topological phases in the kagome superlattice of AV_(3)Sb_(5)

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npj Computational Materials 2022年第1期8卷 624-629页

作者： Thomas Mertz Paul Wunderlich Shinibali Bhattacharyya francesco ferrari roser Valentí institut für theoretische physik Goethe-UniversitätFrankfurt am MainGermany

recent experimental findings have reported the presence of unconventional charge orders in the enlarged(2×2)unit-cell of kagome metals AV3Sb5(A=K,rb,Cs)and hinted towards specific topological signatures.Motivated by these discoveries,we investigate the types of topological phases that can be realized in such kagome superlattices.In this context,we employ a recently introduced statistical method capable of constructing topological models for any generic lattice.By analyzing large data sets generated from symmetry-guided distributions of randomized tight-binding parameters,and labeled with the corresponding topological index,we extract physically meaningful information.We illustrate the possible real-space manifestations of charge and bond modulations and associated flux patterns for different topological classes,and discuss their relation to present theoretical predictions and experimental signatures for the AV_(3)Sb_(5)family.Simultaneously,we predict higher-order topological phases that may be realized by appropriately manipulating the currently known systems.

关键词： topological signature meaningful

Production of the X(4014)as the Spin-2 Partner of X(3872)in e^(+)e^(-)Collisions

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Chinese Physics Letters 2024年第3期41卷 30-36页

作者： Pan-Pan Shi Vadim Baru feng-Kun Guo Christoph Hanhart Alexey Nefediev CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China Departamento de f′ısica Te′orica and IfIC Centro Mixto Universidad de Valencia-CSIC Institutos de Investigaci′on de PaternaAptdo.2208546071 ValenciaSpain institut fur theoretische physik II Ruhr-Universitat BochumD-44780 BochumGermany Peng Huanwu Collaborative Center for research and Education Beihang UniversityBeijing 100191China institute for Advanced Simulation Institut fur Kernphysik and Julich Center for Hadron PhysicsForschungszentrum JulichD-52425 JulichGermany Jozef Stefan institute Jamova 391000LjubljanaSlovenia CefEMA Center of Physics and Engineering of Advanced MaterialsInstituto Superior T′ecnicoAvenida Rovisco Pais 11049-001 LisboaPortugal

In 2021,the Belle collaboration reported the first observation of a new structure in theψ(2S)γfinal state produced in the two-photon fusion process.In the hadronic molecule picture,this new structure can be associatedwith the shallow isoscalar D*D* bound state and as such is an excellent candidate for the spin-2 partner of the X(3872)with the quantum numbers J^(PC)=2^(++)conventionally named X_(2).

关键词： process X(3872) Collisions

A comparison of approaches in fitting continuum SEDs

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research in Astronomy and Astrophysics 2013年第4期13卷 420-434页

作者： Yao Liu David Madlener Sebastian Wolf Hong-Chi Wang Purple Mountain Observatory and Key Laboratory for radio Astronomy Chinese Academy of Sciences Graduate University of Chinese Academy of Sciences institut fr theoretische physik und astrophysik Universitt zu Kiel

We present a detailed comparison of two approaches, the use of a precalculated database and simulated annealing （SA）, for fitting the continuum spectral energy distribution （SED） of astrophysical objects whose appearance is dominated by surrounding dust. While pre-calculated databases are commonly used to model SED data, only a few studies to date employed SA due to its unclear accuracy and convergence time for this specific problem. from a methodological point of view, different approaches lead to different fitting quality, demand on computational resources and calculation time. We compare the fitting quality and computational costs of these two approaches for the task of SED fitting to provide a guide to the practitioner to find a compromise between desired accuracy and available resources. To reduce uncertainties inherent to real datasets, we introduce a reference model resembling a typical circumstellar system with 10 free parameters. We derive the SED of the reference model with our code MC3 D at 78 logarithmically distributed wavelengths in the range [0.3 μm, 1.3 mini and use this setup to simulate SEDs for the database and SA. Our result directly demonstrates the applicability of SA in the field of SED modeling, since the algorithm regularly finds better solutions to the optimization problem than a precalculated database. As both methods have advantages and shortcomings, a hybrid approach is preferable. While the database provides an approximate fit and overall probability distributions for all parameters deduced using Bayesian analysis, SA can be used to improve upon the results returned by the model grid.

关键词： methods numerical - radiative transfer - protoplanetary disks

radiative transfer modeling of three T Tauri stars: selecting candidates for studying circumstellar disk evolution

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research in Astronomy and Astrophysics 2013年第7期13卷 841-848页

作者： Yao Liu Hong-Chi Wang Sebastian Wolf David Madlener Purple Mountain Observatory&Key Laboratory for radio Astronomy Chinese Academy of Sciences Graduate University of Chinese Academy of Sciences institut für theoretische physik und astrophysik Universitt zu Kiel

We present modeling work on three young stellar objects that are promis-ing targets for future high-resolution observations to investigate circumstellar disk evolution. The currently available data comprise the spectral energy distribution from optical to millimeter wavelengths which allow constraining the structure of the cir-cumstellar disk using self-consistent radiative transfer models. The results suggest that the assumption of well-mixed dust and gas leads to overestimation of flux in the far-infrared. Observational and theoretical arguments suggest that an overall decrease in far-infrared excess can be explained by dust settling towards the midplane. A new disk model is hence employed to take the effect of dust sedimentation into account. The extended model satisfactorily reproduces all existing observations. The three tar-gets studied here therefore deserve follow-up observations to reveal the evolutionary state of their protoplanetary disks.

关键词： circumstellar matter - planetary systems： protoplanetary disks - ra-diative transfer

Towards an understanding of Type Ia supernovae from a synthesis of theory and observations

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frontiers of physics 2013年第2期8卷 116-143页

作者： W. Hillebrandt M. Kromer f. K. ropke A. J. ruiter Max-Planck-institut fiir astrophysik Karl-Schwarzschild-Str. 1 D-85741 Garching Germany institut fiir theoretische physik und astrophysik Universit~it Wiirzburg Am Hubland D-97074 Wiirzburg Germany

Motivated by the fact that calibrated light curves of Type Ia supernovae （SNe Ia） have become a major tool to determine the expansion history of the Universe, considerable attention has been given to, both, observations and models of these events over the past 15 years. Here, we summarize new observational constraints, address recent progress in modeling Type Ia supernovae by means of three-dimensional hydrodynamic simulations, and discuss several of the still open questions. It will be be shown that the new models have considerable predictive power which allows us to study observable properties such as light curves and spectra without adjustable non-physical parameters. This is a necessary requisite to improve our understanding of the explosion mechanism and to settle the question of the applicability of SNe Ia as distance indicators for cosmology. We explore the capabilities of the models by comparing them be applied to study the origin of the diversity with observations and we show how such models can of SNe Ia.

关键词： supernovae nucleosynthesis stellar evolution binary and multiple stars nuclearreactions

formation of Superheavy Nuclei in Massive fusion reactions

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原子核物理评论 2009年第S1期26卷 168-174页

作者： Scheid Werner institut fr theoretische physik der Universitt

Within the concept of the dinuclear system(DNS),by incorporating the coupling of the relative motion to the nucleon transfer process,a dynamical model is proposed for describing the formation of superheavy residue nucleus in massive fusion reactions,in which the capture of two heavy colliding nuclei,the formation of compound nucleus and the de-excitation process are calculated using empirical coupled channel model,solving master equation numerically and statistical theory,respectively. By using the DNS model,the evaporation-residue excitation functions in the 48Ca induced fusion reactions and in the cold fusion reactions are investigated systematically and compared with available experimental data. Optimal evaporation channels and combinations as well as the corresponding excitation energies are proposed. The possible factors that influencing the isotopic dependence of the production cross sections are analyzed. The formation of the superheavy nuclei based on the isotopes U with different projectiles are also investigated.

关键词： DNS model massive fusion reaction evaporation-residue excitation function