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Dirac Theory in Noncommutative Phase Spaces 非交换相空间中的狄拉克理论
Pub Date : 2024-07-08 DOI: 10.3390/physics6030058
Shi‐Dong Liang
Based on the position and momentum of noncommutative relations with a noncanonical map, we study the Dirac equation and analyze its parity and time reversal symmetries in a noncommutative phase space. Noncommutative parameters can be endowed with the Planck length and cosmological constant such that the noncommutative effect can be interpreted as an effective gauge potential or a (0,2)-type curvature associated with the Plank constant and cosmological constant. This provides a natural coupling between dynamics and spacetime geometry. We find that a free Dirac particle carries an intrinsic velocity and force induced by the noncommutative algebra. These properties provide a novel insight into the Zitterbewegung oscillation and the physical scenario of dark energy. Using perturbation theory, we derive the perturbed and nonrelativistic solutions of the Dirac equation. The asymmetric vacuum gaps of particles and antiparticles reveal the particle–antiparticle symmetry breaking in the noncommutative phase space, which provides a clue to understanding the physical mechanisms of particle–antiparticle asymmetry and quantum decoherence through quantum spacetime fluctuation.
基于具有非对称映射的非交换关系的位置和动量,我们研究了狄拉克方程,并分析了它在非交换相空间中的奇偶性和时间反转对称性。非交换参数可以被赋予普朗克长度和宇宙学常数,这样非交换效应就可以被解释为有效的规势或与普朗克常数和宇宙学常数相关的(0,2)型曲率。这提供了动力学与时空几何之间的自然耦合。我们发现,自由的狄拉克粒子携带着由非交换代数诱导的内在速度和力。这些特性为我们深入了解齐特贝格振荡和暗能量的物理情景提供了新的视角。利用摄动理论,我们推导出了狄拉克方程的摄动和非相对论解。粒子和反粒子的非对称真空间隙揭示了非交换相空间中粒子-反粒子对称性的破缺,为理解粒子-反粒子不对称和通过量子时空波动实现量子退相干的物理机制提供了线索。
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引用次数: 0
Avogadro and Planck Constants, Two Pillars of the International System of Units 阿伏加德罗常数和普朗克常数,国际单位制的两大支柱
Pub Date : 2024-06-03 DOI: 10.3390/physics6020052
Enrico Massa
The International System of Units (SI), the current form of the metric system and the world’s most used system of units, has been continuously updated and refined since the Metre Convention of 1875 to ensure that it remains up to date with the latest scientific and technological advances. The General Conference on Weights and Measures, at its 26th meeting in 2018, decided to adopt stipulated values of seven physical constants linked to seven measurement units (the second, meter, kilogram, ampere, kelvin, mole, and candela). This paper reviews the technologies developed, in intense and long-standing work, to determine the Avogadro and Planck constants, which are now integral to realising the kilogram.
国际单位制(SI)是公制的现行形式,也是世界上使用最多的单位制,自 1875 年《米公约》以来,国际单位制一直在不断更新和完善,以确保其跟上最新的科技进步。2018 年,度量衡大会第 26 次会议决定采用与七个计量单位(秒、米、千克、安培、开尔文、摩尔和坎德拉)相关联的七个物理常数的规定值。本文回顾了在紧张而长期的工作中为确定阿伏加德罗常数和普朗克常数而开发的技术,这两个常数现已成为实现千克的组成部分。
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引用次数: 0
Swirling Capillary Instability of Rivlin–Ericksen Liquid with Heat Transfer and Axial Electric Field 具有热传导和轴向电场的里夫林-埃里克森液体的漩涡毛细管不稳定性
Pub Date : 2024-06-03 DOI: 10.3390/physics6020051
Dhananjay Yadav, M. K. Awasthi, Ashwani Kumar, N. Dutt
The mutual influences of the electric field, rotation, and heat transmission find applications in controlled drug delivery systems, precise microfluidic manipulation, and advanced materials’ processing techniques due to their ability to tailor fluid behavior and surface morphology with enhanced precision and efficiency. Capillary instability has widespread relevance in various natural and industrial processes, ranging from the breakup of liquid jets and the formation of droplets in inkjet printing to the dynamics of thin liquid films and the behavior of liquid bridges in microgravity environments. This study examines the swirling impact on the instability arising from the capillary effects at the boundary of Rivlin–Ericksen and viscous liquids, influenced by an axial electric field, heat, and mass transmission. Capillary instability arises when the cohesive forces at the interface between two fluids are disrupted by perturbations, leading to the formation of characteristic patterns such as waves or droplets. The influence of gravity and fluid flow velocity is disregarded in the context of capillary instability analyses. The annular region is formed by two cylinders: one containing a viscous fluid and the other a Rivlin–Ericksen viscoelastic fluid. The Rivlin–Ericksen model is pivotal for comprehending the characteristics of viscoelastic fluids, widely utilized in industrial and biological contexts. It precisely characterizes their rheological complexities, encompassing elasticity and viscosity, critical for forecasting flow dynamics in polymer processing, food production, and drug delivery. Moreover, its applications extend to biomedical engineering, offering insights crucial for medical device design and understanding biological phenomena like blood flow. The inside cylinder remains stationary, and the outside cylinder rotates at a steady pace. A numerically analyzed quadratic growth rate is obtained from perturbed equations using potential flow theory and the Rivlin–Ericksen fluid model. The findings demonstrate enhanced stability due to the heat and mass transfer and increased stability from swirling. Notably, the heat transfer stabilizes the interface, while the density ratio and centrifuge number also impact stability. An axial electric field exhibits a dual effect, with certain permittivity and conductivity ratios causing perturbation growth decay or expansion.
电场、旋转和热传导的相互影响可应用于可控给药系统、精确的微流体操作和先进的材料加工技术,因为它们能够以更高的精度和效率调整流体行为和表面形态。毛细管不稳定性在各种自然和工业过程中具有广泛的相关性,从喷墨打印中液体射流的破裂和液滴的形成,到薄液体薄膜的动力学和微重力环境中液桥的行为,不一而足。本研究探讨了漩涡对里夫林-埃里克森和粘性液体边界毛细管效应引起的不稳定性的影响,这种不稳定性受到轴向电场、热量和质量传输的影响。毛细管不稳定性产生于两种液体界面的内聚力被扰动破坏,导致波浪或液滴等特征模式的形成。毛细管不稳定性分析不考虑重力和流体流速的影响。环形区域由两个圆柱体构成:一个包含粘性流体,另一个包含 Rivlin-Ericksen 粘弹性流体。Rivlin-Ericksen 模型是理解粘弹性流体特性的关键,广泛应用于工业和生物领域。它能精确描述流变的复杂性,包括弹性和粘度,对于预测聚合物加工、食品生产和药物输送中的流动动力学至关重要。此外,它的应用还扩展到生物医学工程领域,为医疗设备设计和理解血液流动等生物现象提供了至关重要的见解。内圆柱体保持静止,外圆柱体以稳定的速度旋转。利用势流理论和里夫林-埃里克森流体模型,从扰动方程中获得了数值分析的二次增长率。研究结果表明,传热和传质增强了稳定性,漩涡增强了稳定性。值得注意的是,热传递使界面更加稳定,而密度比和离心数也会影响稳定性。轴向电场表现出双重效应,特定的介电常数和电导率比率会导致扰动增长衰减或膨胀。
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引用次数: 0
Statistical Mechanics of Social Hierarchies: A Mathematical Model for the Evolution of Human Societal Structures 社会等级的统计力学:人类社会结构进化的数学模型
Pub Date : 2024-04-19 DOI: 10.3390/physics6020041
Nestor Caticha, Rafael S. Calsaverini, R. Vicente
Social structure may have changed from hierarchical to egalitarian and back along the evolutionary line of humans. Within the tradition of sociophysics, we construct a mathematical model of a society of agents subject to competing cognitive and social navigation constraints and predict, using statistical mechanics methods, that its degree of hierarchy decreases with encephalization and increases with group size, hence suggesting human societies were driven from hierarchical to egalitarian structures by the encephalization during the last few million years and back to hierarchical due to fast demographic changes during the Neolithic. In addition, applied to a different problem, the theory leads to the following predictions for modern pre-literary humans: (i) an intermediate hierarchy degree in mild climates. In harsher climates, societies will be (ii) more egalitarian if organized in small groups (of less than 100 persons) but (iii) more hierarchical if in larger (of more than 1000 persons) groups. The predicted bifurcation, characteristic of a phase transition, is also seen in the empirical cross-cultural record (248 cultures in the Ethnographic Atlas).
在人类的进化过程中,社会结构可能从等级制变为平等制,又从平等制变回等级制。在社会物理学的传统下,我们构建了一个由受到认知和社会导航限制的代理人组成的社会的数学模型,并利用统计力学方法预测其等级程度会随着脑化程度的降低而降低,并随着群体规模的扩大而增加,从而表明人类社会在过去的几百万年中由于脑化而从等级结构变为平等结构,又由于新石器时代人口的快速变化而回到等级结构。此外,将该理论应用于不同的问题,可以对现代前文盲人类做出如下预测:(i) 在温和的气候条件下,等级制度处于中间水平。在较恶劣的气候条件下,如果是小群体(少于 100 人),社会将(ii)更加平等,但如果是大群体(多于 1000 人),社会将(iii)更加等级森严。在跨文化的经验记录(《人种图集》中有 248 种文化)中,也可以看到所预测的分叉现象,即阶段性转变的特征。
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引用次数: 0
Casimir Energy in (2 + 1)-Dimensional Field Theories 2 + 1)维场理论中的卡西米尔能
Pub Date : 2024-04-17 DOI: 10.3390/physics6020040
M. Asorey, Claudio Iuliano, Fernando Ezquerro
We explore the dependence of vacuum energy on the boundary conditions for massive scalar fields in (2 + 1)-dimensional spacetimes. We consider the simplest geometrical setup given by a two-dimensional space bounded by two homogeneous parallel wires in order to compare it with the non-perturbative behaviour of the Casimir energy for non-Abelian gauge theories in (2 + 1) dimensions. Our results show the existence of two types of boundary conditions which give rise to two different asymptotic exponential decay regimes of the Casimir energy at large distances. The two families are distinguished by the feature that the boundary conditions involve or not interrelations between the behaviour of the fields at the two boundaries. Non-perturbative numerical simulations and analytical arguments show such an exponential decay for Dirichlet boundary conditions of SU(2) gauge theories. The verification that this behaviour is modified for other types of boundary conditions requires further numerical work. Subdominant corrections in the low-temperature regime are very relevant for numerical simulations, and they are also analysed in this paper.
我们探讨了真空能对 (2 + 1) 维空间中大质量标量场的边界条件的依赖性。我们考虑了最简单的几何设置,即由两根同质平行线围成的二维空间,以便将其与非阿贝尔规规理论在 (2 + 1) 维中的卡西米尔能的非微扰行为进行比较。我们的研究结果表明存在两种边界条件,它们导致了卡西米尔能在大距离上的两种不同渐近指数衰减状态。这两个系列的区别在于边界条件涉及或不涉及两个边界的场行为之间的相互关系。非微扰数值模拟和分析论证表明,SU(2)规理论的迪里夏特边界条件存在这种指数衰减。要验证这种行为在其他类型的边界条件下是否有所改变,还需要进一步的数值工作。低温制度下的次主导修正与数值模拟非常相关,本文也对其进行了分析。
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引用次数: 0
Critical Temperature and Critical Current Enhancement in Arrays of Josephson Junctions: A Ginzburg–Landau Perspective 约瑟夫森结阵列的临界温度和临界电流增强:金兹堡-朗道视角
Pub Date : 2024-04-15 DOI: 10.3390/physics6020039
Elena Tomei, Riccardo Bizzi, Vittorio Merlo, F. Romeo, Gaetano Salina, Matteo Cirillo
The present investigation explores the spatial distribution of Cooper pair density in graph-shaped arrays of Josephson junctions using a Ginzburg–Landau approach. We specifically investigate double-comb structures and compare their properties with linear arrays as reference systems. Our findings reveal that the peculiar connectivity of the double-comb structure leads to spatial gradients in the order parameter, which can be readily detected through measurements of Josephson critical currents. We present experimental results which indicate the specific dependence of the order parameter on the branches of the graphs and are evidence of the theoretical predictions.
本研究采用金兹堡-朗道(Ginzburg-Landau)方法,探讨了约瑟夫森结图形阵列中库珀对密度的空间分布。我们特别研究了双梳结构,并将其特性与作为参考系统的线性阵列进行了比较。我们的研究结果表明,双梳状结构奇特的连通性导致了阶次参数的空间梯度,这可以通过测量约瑟夫森临界电流轻易地探测到。我们提出的实验结果表明了阶次参数对图形分支的特定依赖性,并证明了理论预测。
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引用次数: 0
Ultrafast Resonant Photon Emission from a Molecule Driven by a Strong Coherent Field in Terms of Complex Spectral Analysis 从复杂光谱分析看强相干场驱动的分子超快共振光子发射
Pub Date : 2024-04-11 DOI: 10.3390/physics6020038
Maito Katayama, Satoshi Tanaka, K. Kanki
In this study, we investigate the time–frequency-resolved resonant photon emission from a molecular vibrational oscillator driven by a monochromatic coherent external field. Using the complex spectral analysis of the Liouvillian, which integrates irreversible dissipative phenomena into quantum theory, we elucidate the fundamental processes of photon emission. Indeed, our analytical approach successfully decomposes the emission spectrum into two intrinsic contributions: one from a resonance eigenmode and another from continuous eigenmodes. These components are responsible for incoherent luminescence and coherent scattering photon emission processes, respectively. Our results show that while spontaneous emission dominates in the early stages of the emission process, coherent scattering gradually becomes more pronounced with time. Furthermore, destructive quantum interference between the two components plays a key role in determining the overall shape of the emission spectrum.
在这项研究中,我们研究了由单色相干外场驱动的分子振动振子的时频分辨共振光子发射。利用将不可逆耗散现象整合到量子理论中的 Liouvillian 复杂光谱分析,我们阐明了光子发射的基本过程。事实上,我们的分析方法成功地将发射光谱分解为两个内在贡献:一个来自共振特征模式,另一个来自连续特征模式。这些成分分别负责非相干发光和相干散射光子发射过程。我们的研究结果表明,虽然自发辐射在发射过程的早期阶段占主导地位,但随着时间的推移,相干散射逐渐变得更加明显。此外,这两种成分之间的破坏性量子干涉在决定发射光谱的整体形状方面起着关键作用。
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引用次数: 0
Nanosecond-Laser-Induced Breakdown of Aqueous Colloidal Solutions of Dysprosium Nanoparticles: The Influence of Nanoparticle Concentration on the Breakdown Plasma and the Intensity of Physical and Chemical Processes 纳秒激光诱导镝纳米粒子胶体水溶液的击穿:纳米粒子浓度对击穿等离子体以及物理和化学过程强度的影响
Pub Date : 2024-04-09 DOI: 10.3390/physics6020035
I. V. Baimler, Alexey S. Baryshev, Anastasiya O. Dikovskaya, V. K. Chevokin, O. V. Uvarov, M. Astashev, S. Gudkov, A. V. Simakin
This paper studies the dynamics of the development of laser breakdown plasma in aqueous colloids of dysprosium nanoparticles by analyzing the time patterns of plasma images obtained using a high-speed streak camera. In addition, the distribution of plasma flashes in space and their luminosity were studied, and the amplitude of acoustic signals and the rate of generation of new chemical products were studied depending on the concentration of dysprosium nanoparticles in the colloid. Laser breakdown was initiated by pulsed radiation from a nanosecond Nd:YAG laser. It is shown that the size of the plasma flash, the speed of motion of the plasma–liquid interface, and the lifetime of the plasma flash decrease with an increasing concentration of nanoparticles in the colloid. In this case, the time delay between the beginning of the laser pulse and the moment the plasma flash reaches its maximum intensity increases with increasing concentrations of nanoparticles. Varying the laser fluence in the range from 67 J/cm2 to 134 J/cm2 does not lead to noticeable changes in these parameters, due to the transition of the breakdown plasma to the critical regime. For dysprosium nanoparticles during laser breakdown of colloids, a decrease in the yield of hydrogen peroxide and an increase in the rate of formation of hydroxyl radicals per water molecule, characteristic of nanoparticles of rare earth metals, are observed, which may be due to the participation of nanoparticles and hydrogen peroxide in reactions similar to the Fenton and Haber–Weiss reactions.
本文通过分析使用高速条纹照相机获得的等离子体图像的时间模式,研究了镝纳米粒子水胶体中激光击穿等离子体的发展动态。此外,还研究了等离子体闪光在空间的分布及其亮度,并根据胶体中镝纳米粒子的浓度研究了声学信号的振幅和新化学产品的生成率。激光击穿是由纳秒 Nd:YAG 激光器的脉冲辐射引发的。结果表明,随着胶体中纳米粒子浓度的增加,等离子闪的大小、等离子体-液体界面的运动速度以及等离子闪的寿命都会减小。在这种情况下,从激光脉冲开始到等离子体闪光达到最大强度之间的时间延迟会随着纳米颗粒浓度的增加而增加。在 67 J/cm2 到 134 J/cm2 的范围内改变激光通量不会导致这些参数发生明显变化,这是因为击穿等离子体已过渡到临界状态。对于激光击穿胶体过程中的镝纳米粒子,观察到稀土金属纳米粒子特有的过氧化氢产率降低和每个水分子羟基自由基形成率增加,这可能是由于纳米粒子和过氧化氢参与了类似芬顿反应和哈伯-魏斯反应的反应。
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引用次数: 0
Casimir Interaction of Chern–Simons Layers on Substrates via Vacuum Stress Tensor 通过真空应力张量实现基底上切尔-西蒙斯层的卡西米尔相互作用
Pub Date : 2024-04-02 DOI: 10.3390/physics6020033
V. Marachevsky, A. Sidelnikov
We develop a Green’s functions scattering method for systems with Chern–Simons plane boundary layers on dielectric half-spaces. The Casimir pressure is derived by evaluation of the stress tensor in a vacuum slit between two half-spaces. The sign of the Casimir pressure on a Chern–Simons plane layer separated by a vacuum slit from the Chern–Simons layer at the boundary of a dielectric half-space is analyzed for intrinsic Si and SiO2 glass substrates.
我们针对介电半空间上的切尔-西蒙平面边界层系统开发了一种格林函数散射方法。卡西米尔压力是通过评估两个半空间之间真空狭缝中的应力张量得出的。针对本征 Si 和 SiO2 玻璃衬底,分析了被真空缝隙与介电半空间边界上的 Chern-Simons 层隔开的 Chern-Simons 平面层上的卡西米尔压力的符号。
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引用次数: 0
A Theory of Best Choice Selection through Objective Arguments Grounded in Linear Response Theory Concepts 基于线性反应理论概念的客观论证最佳选择选择理论
Pub Date : 2024-03-27 DOI: 10.3390/physics6020031
Marcel Ausloos, Giulia Rotundo, Roy Cerqueti
In this study, we propose how to use objective arguments grounded in statistical mechanics concepts in order to obtain a single number, obtained after aggregation, which would allow for the ranking of “agents”, “opinions”, etc., all defined in a very broad sense. We aim toward any process which should a priori demand or lead to some consensus in order to attain the presumably best choice among many possibilities. In order to specify the framework, we discuss previous attempts, recalling trivial means of scores—weighted or not—Condorcet paradox, TOPSIS (Technique for Order Preference by Similarity to Ideal Solution), etc. We demonstrate, through geometrical arguments on a toy example and with four criteria, that the pre-selected order of criteria in previous attempts makes a difference in the final result. However, it might be unjustified. Thus, we base our “best choice theory” on the linear response theory in statistical physics: we indicate that one should be calculating correlations functions between all possible choice evaluations, thereby avoiding an arbitrarily ordered set of criteria. We justify the point through an example with six possible criteria. Applications in many fields are suggested. Furthermore, two toy models, serving as practical examples and illustrative arguments are discussed.
在这项研究中,我们提出了如何使用以统计力学概念为基础的客观论据,以便在汇总后获得一个单一的数字,从而对 "代理人"、"意见 "等进行排序,所有这些都是在非常广泛的意义上定义的。我们的目标是在任何过程中,先验地要求或导致某种共识,以便在众多可能性中获得假定的最佳选择。为了明确这一框架,我们讨论了以往的尝试,回顾了分数的琐碎手段--加权或非加权--康德塞特悖论、TOPSIS(通过与理想解的相似性排序偏好的技术)等。我们通过对一个玩具范例和四个标准的几何论证来证明,先前尝试中预先选择的标准顺序会对最终结果产生影响。然而,这可能是不合理的。因此,我们的 "最佳选择理论 "以统计物理学中的线性响应理论为基础:我们指出,应该计算所有可能的选择评价之间的相关函数,从而避免任意排序的标准集。我们通过一个有六种可能标准的例子来证明这一点。我们还提出了在许多领域的应用。此外,我们还讨论了两个玩具模型,作为实际例子和说明性论据。
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引用次数: 0
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