Brazilian Journal of Physics最新文献_第2页

Analytical Treatment of a Nonlinear Rate Equation for Laser-induced Breakdown Under Symmetry-controlled Excitation 对称控制激励下激光诱导击穿非线性速率方程的解析处理

IF 1.7 4区物理与天体物理

Brazilian Journal of Physics Pub Date : 2026-04-27 DOI: 10.1007/s13538-026-02083-x

Hristina Delibašić-Marković, Violeta Petrović, Ivan Petrović

{"title":"Analytical Treatment of a Nonlinear Rate Equation for Laser-induced Breakdown Under Symmetry-controlled Excitation","authors":"Hristina Delibašić-Marković, Violeta Petrović, Ivan Petrović","doi":"10.1007/s13538-026-02083-x","DOIUrl":"10.1007/s13538-026-02083-x","url":null,"abstract":"<div>\u0000 \u0000 <p>A nonlinear rate-equation formulation of nanosecond laser-induced breakdown in water-like media is developed, with polarization ellipticity introduced as a continuous symmetry parameter of the driving field. The rotational structure of the excitation is embedded directly into the governing equation for the free-electron density, enabling a systematic examination of avalanche ionization dynamics. A closed-form analytical solution of the nonlinear evolution equation is derived and its predictions are compared with independent numerical calculations. The results demonstrate that symmetry enters the governing amplification structure of the system, modifying the effective growth mechanism that controls plasma formation. To characterize this dependence in a compact and physically transparent manner, two global measures are introduced: the suppression factor of the peak electron density and the characteristic delay time of breakdown onset. The proposed formulation provides a mathematically consistent framework for analysing symmetry-controlled ionization processes in the nanosecond regime and supports modelling of laser-matter interaction in condensed media relevant to biomedical and engineering applications.</p>\u0000 </div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"56 3","pages":""},"PeriodicalIF":1.7,"publicationDate":"2026-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147796940","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Nontrivial Local Observables and Impermeable and Permeable Boundary Conditions for 1D KFGM Particles 一维KFGM粒子的非平凡局部观测值和不透、不透边界条件

IF 1.7 4区物理与天体物理

Brazilian Journal of Physics Pub Date : 2026-04-27 DOI: 10.1007/s13538-026-02072-0

Techapon Kampu, Salvatore De Vincenzo

{"title":"Nontrivial Local Observables and Impermeable and Permeable Boundary Conditions for 1D KFGM Particles","authors":"Techapon Kampu, Salvatore De Vincenzo","doi":"10.1007/s13538-026-02072-0","DOIUrl":"10.1007/s13538-026-02072-0","url":null,"abstract":"<div>\u0000 \u0000 <p>Real solutions of the 1D Klein-Fock-Gordon (KFG) equation automatically cancel out the usual two-vector current density; consequently, the respective continuity equation is trivially satisfied, and a globally conserved quantity cannot be obtained. Additionally, distinguishing between impermeable and permeable boundary conditions (BCs) at a given point is not possible. We address these first-quantized conflicts by using the simplest nontrivial local observables, i.e., an energy density and an energy current density, which allows us to characterize a strictly neutral 1D KFG particle, i.e., a 1D KFG-Majorana (KFGM) particle, when it is confined to an interval and when it is restricted, e.g., in an interval with transparent walls. All the BCs for this system are extracted from the pseudo self-adjointness of the Feshbach-Villars (FV) Hamiltonian plus two Majorana conditions. We show that these energy densities are components of an unusual energy-momentum tensor and can satisfy a continuity equation, leading to a conserved quantity for all available BCs. Moreover, the energy current density can characterize all the BCs as either impermeable or permeable. In contrast, the commonly used energy current density—a component of the usual energy-momentum tensor—cannot characterize all the BCs. Additionally, this quantity and its respective energy density—another component of the usual energy-momentum tensor—may not lead to a conserved quantity. We also obtain the BCs for which the abovementioned densities and those commonly used are equally satisfactory. In fact, this occurs only for four impermeable BCs and a one-parameter set of permeable BCs. Our results highlight the important role played by the BCs when they are imposed on a system in which particles occupy a finite region.</p>\u0000 </div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"56 3","pages":""},"PeriodicalIF":1.7,"publicationDate":"2026-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147796889","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Comparative Physical and Physicochemical Characterization of Normal Saline Activated by two Atmospheric-pressure Plasma Systems 两种常压等离子体系统活化生理盐水的理化特性比较

IF 1.7 4区物理与天体物理

Brazilian Journal of Physics Pub Date : 2026-04-27 DOI: 10.1007/s13538-026-02082-y

Maryam G. Jasim, Hammad R. Humud

{"title":"Comparative Physical and Physicochemical Characterization of Normal Saline Activated by two Atmospheric-pressure Plasma Systems","authors":"Maryam G. Jasim, Hammad R. Humud","doi":"10.1007/s13538-026-02082-y","DOIUrl":"10.1007/s13538-026-02082-y","url":null,"abstract":"<div>\u0000 \u0000 <p>Plasma–liquid interaction is an effective approach for generating chemically active solutions with potential applications in plasma medicine, environmental treatment, and biomedical technologies. In this work, a comparative study was performed to investigate the activation of normal saline using two atmospheric-pressure plasma systems that use the same Ar–O₂ feeding gas mixture: atmospheric-pressure plasma jet (APPJ) and dielectric barrier discharge (DBD). Excited species, including OH, O, Ar, and N₂, were validated by optical emission spectroscopy, showing active plasma processes and contact with surrounding air. As exposure duration increased, plasma therapy dramatically changed the saline solution’s physicochemical characteristics. The pH decreased from approximately 6.4 to nearly 4.0, while the oxidation–reduction potential (ORP) increased to about 480 mV, indicating the formation of a strongly oxidative environment. Reactive species accumulated progressively in the liquid phase. The DBD system produced higher concentrations of hydrogen peroxide and nitrate, reaching about 250 ppm after 20 min of treatment, whereas the plasma jet generated lower nitrate levels but showed a stronger increase in electrical conductivity, rising from about 15.5 to nearly 28 mS cm⁻¹. In addition, the plasma jet exhibited slightly higher nitrite accumulation at longer treatment times. These findings demonstrate that although both plasma systems effectively activate saline solution, the plasma configuration plays a critical role in determining reactive species generation and the resulting physicochemical characteristics of the liquid. This comparative analysis provides important insight into plasma–liquid interaction mechanisms and highlights the importance of discharge design in tailoring plasma-activated solutions for future biomedical and environmental applications.</p>\u0000 </div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"56 3","pages":""},"PeriodicalIF":1.7,"publicationDate":"2026-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147796890","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Generalized Wick’s Theorem at Finite Temperature and Non-Poissonian Fluctuations in Weakly Interacting Bose Gases 有限温度下的广义威克定理和弱相互作用玻色气体中的非泊松涨落

IF 1.7 4区物理与天体物理

Brazilian Journal of Physics Pub Date : 2026-04-27 DOI: 10.1007/s13538-026-02080-0

M. O. C. Pires

{"title":"Generalized Wick’s Theorem at Finite Temperature and Non-Poissonian Fluctuations in Weakly Interacting Bose Gases","authors":"M. O. C. Pires","doi":"10.1007/s13538-026-02080-0","DOIUrl":"10.1007/s13538-026-02080-0","url":null,"abstract":"<div>\u0000 \u0000 <p>In Ref. Gaudin (Nuclear Physics <b>15</b>, 89 1960), Gaudin established a generalized version of Wick’s theorem at finite temperature for systems described by a diagonal quadratic Hamiltonian. In this work, we extend Gaudin’s proof to statistical density operators generated by a general quadratic Hamiltonian, prior to diagonalization, as commonly encountered in interacting Bose systems. We show explicitly that the resulting thermal contractions depend on the Bogoliubov transformation parameters and on the quasiparticle spectrum, providing a transparent framework for evaluating thermal averages of arbitrary operator products. As an illustration of the usefulness of this generalized formulation, we evaluate particle-number fluctuations in a homogeneous, weakly interacting Bose gas below the Bose–Einstein condensation temperature. We show that particle-number fluctuations are generically non-Poissonian as a consequence of interaction-induced correlations and quantum depletion, with the Poissonian limit recovered only for an ideal Bose gas at zero temperature. Our results clarify the role of quadratic Hamiltonians and Bogoliubov quasiparticles in shaping fluctuation statistics and highlight the generalized Wick’s theorem as a controlled tool for computing correlation functions in interacting quantum gases.</p>\u0000 </div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"56 3","pages":""},"PeriodicalIF":1.7,"publicationDate":"2026-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s13538-026-02080-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147796939","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Remarks on Constraint Analysis and Vacuum Persistence Amplitudes in Gauge Theories 规范理论中的约束分析和真空持续振幅评述

IF 1.7 4区物理与天体物理

Brazilian Journal of Physics Pub Date : 2026-04-24 DOI: 10.1007/s13538-026-02074-y

A. A. Nogueira

引用次数: 0

Limits on QED-Induced Decoherence in the Stern-Gerlach Experiment Stern-Gerlach实验中qed诱导退相干的限制

IF 1.7 4区物理与天体物理

Brazilian Journal of Physics Pub Date : 2026-04-24 DOI: 10.1007/s13538-026-02085-9

C. A. Dartora

引用次数: 0

IF 1.7 4区物理与天体物理

Brazilian Journal of Physics Pub Date : 2026-04-23 DOI: 10.1007/s13538-026-02063-1

Cristian G. Bernal, Samuel D. Sales, Carlos A. Galíndez

{"title":"Self-Similar Morphological Templates for Axisymmetric Accretion–Outflow Structures","authors":"Cristian G. Bernal, Samuel D. Sales, Carlos A. Galíndez","doi":"10.1007/s13538-026-02063-1","DOIUrl":"10.1007/s13538-026-02063-1","url":null,"abstract":"<div><p>We present a three-parameter, self-similar family of steady, axisymmetric, nonrelativistic solutions that unifies the morphology, kinematics, and viscous transport of accretion–ejection flows. The triplet <span>((alpha ,beta ,gamma ))</span> governs the radial power-law indices of angular velocity, density, and kinematic viscosity, respectively. In the inviscid limit, the geometric index <span>(alpha)</span> continuously organizes the flow topology—from flared, toroidal envelopes (<span>(alpha <2)</span>) through the cylindrical limit (<span>(alpha =2)</span>) to collimated, jet-like funnels (<span>(alpha>2)</span>)—while the stratification index <span>(beta)</span> controls mass loading and helical pitch. Introducing a scale-free viscosity <span>(nu (r)propto r^{gamma })</span> preserves separability and yields an analytic viscous correction <span>(propto r^{gamma -1})</span> to the meridional velocities, with amplitude set by a coupling <span>(V_{gamma })</span>. This framework provides closed-form expressions for velocity fields, streamlines, and stream surfaces, enabling quantitative morphology diagnostics such as the opening-angle profile <span>(psi (theta ))</span> and contour-based RMSE for direct comparison with simulations or observations. The resulting <span>((alpha ,beta ,gamma ))</span> atlas defines a transparent analytic baseline for global HD/GRMHD models, clarifies how viscosity tilts self-similar stream surfaces, and offers benchmark solutions for reduced or physics-informed neural network surrogates.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"56 3","pages":""},"PeriodicalIF":1.7,"publicationDate":"2026-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s13538-026-02063-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147738702","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Computational Study on Structural, Mechanical, Electronic and Optical Properties of La(_{2})ZrSe(_{5}) Chalcogenide for Optoelectronic Applications La (_{2}) ZrSe (_{5})光电子应用硫系化合物结构、力学、电子和光学性质的计算研究

IF 1.7 4区物理与天体物理

Brazilian Journal of Physics Pub Date : 2026-04-23 DOI: 10.1007/s13538-026-02077-9

Vicky Mayaka, Elkana Rugut, Calford Otieno

{"title":"Computational Study on Structural, Mechanical, Electronic and Optical Properties of La(_{2})ZrSe(_{5}) Chalcogenide for Optoelectronic Applications","authors":"Vicky Mayaka, Elkana Rugut, Calford Otieno","doi":"10.1007/s13538-026-02077-9","DOIUrl":"10.1007/s13538-026-02077-9","url":null,"abstract":"<div>\u0000 \u0000 <p>First-principles approach was used to explore the structural, mechanical, electronic and optical properties of the chalcogenide compound La<span>(_{2})</span>ZrSe<span>(_{5})</span> in its orthorhombic phase. To the best of one’s knowledge, a number of this compound’s physical characteristics, including its electronic properties, mechanical behavior, optical dispersion behavior and vibrational characteristics are still understudied. The calculated lattice parameters and unit cell volume are compared with those from previous research to check the reliability of our findings. By analyzing its elastic constants, the mechanical stability of La<span>(_{2})</span>ZrSe<span>(_{5})</span> is evaluated, showing its mechanical resilience. The material’s analysis of mechanical descriptors, including the independent elastic coefficients of bulk, shear and Young’s modulus, as well as ratios such as Pugh’s and Poisson’s ratio, suggests anisotropic and ductile behavior. The electronic properties were further examined by figuring out the band structure, partial and total density of states. According to the findings, La<span>(_{2})</span>ZrSe<span>(_{5})</span> is a semiconductor with a fundamental band gap of approximately 1.25 eV as computed using hybrid functional, suggesting that it may find use in optoelectronics such as photodetectors, field effect transistors, light-emitting diodes and electronics. This work will provide helpful guidance for future experiments and theoretical investigations of the material.</p>\u0000 </div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"56 3","pages":""},"PeriodicalIF":1.7,"publicationDate":"2026-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147738703","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Polarization-Tunable Lasing from Chiral Quasi-Bound State in the Continuum in Dielectric Metasurfaces 介电超表面连续介质中手性准束缚态的偏振可调谐激光

IF 1.7 4区物理与天体物理

Brazilian Journal of Physics Pub Date : 2026-04-17 DOI: 10.1007/s13538-026-02057-z

Zhijian Qiu, Guiyang Hou, Yingjie Ju, Wudeng Wang

{"title":"Polarization-Tunable Lasing from Chiral Quasi-Bound State in the Continuum in Dielectric Metasurfaces","authors":"Zhijian Qiu, Guiyang Hou, Yingjie Ju, Wudeng Wang","doi":"10.1007/s13538-026-02057-z","DOIUrl":"10.1007/s13538-026-02057-z","url":null,"abstract":"<div>\u0000 \u0000 <p>Chiral bound states in the continuum (BICs) in dielectric metasurfaces provide a compelling route to control light–matter interactions through high-quality resonances with strong polarization sensitivity. Here, we numerically demonstrate a tunable nanolaser based on chiral quasi-BICs supported by an all-dielectric metasurface composed of asymmetric InP semicircular rings. Breaking in-plane inversion symmetry enables a magnetic quadrupole-mediated chiral quasi-BIC that exhibits distinctly different Q-factors and near-field enhancements under LCP and RCP excitation. Capitalizing on this polarization-selective confinement, we achieve tunable lasing with ultralow thresholds of 10.97 µJ/cm² (LCP) and 8.32 µJ/cm² (RCP), attributed to asymmetric quasi-BIC radiation coupling. Furthermore, the lasing emission shows spectral narrowing from ~ 11 nm to sub-nanometer linewidths and a 10⁶-fold intensity contrast between LCP and RCP at identical pump fluence. Our work establishes chiral quasi-BICs as a robust platform for dynamically reconfigurable nanolasers, with promising applications in polarization-sensitive photonics, chiral emission control, and adaptive optical systems.</p>\u0000 </div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"56 3","pages":""},"PeriodicalIF":1.7,"publicationDate":"2026-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147738091","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Photon Emission Rate From Heavy-Ion Collision 重离子碰撞的光子发射速率

IF 1.7 4区物理与天体物理

Brazilian Journal of Physics Pub Date : 2026-04-15 DOI: 10.1007/s13538-026-02069-9

Kanshokmi Tuithung, S. Somorendro Singh

引用次数: 0