物理最新文献

{"title":"Gradient expansion formalism for a generic model of inflationary magnetogenesis","authors":"A. V. Lysenko","doi":"10.1140/epjc/s10052-025-14269-9","DOIUrl":"10.1140/epjc/s10052-025-14269-9","url":null,"abstract":"<div><p>We study the generation of electromagnetic fields during inflation in a model with kinetic and axial couplings to the inflaton field using the gradient expansion formalism. This formalism allows us to simultaneously take into account the possible presence of two nonlinear phenomena: (i) the backreaction of the generated electromagnetic fields on the evolution of the inflaton and (ii) the creation of pairs of charged fermions from the physical vacuum (the Schwinger effect). We model the latter phenomenon by using the generalized Ohmic form of the induced current, <span>(vec {J}=sigma _{E}vec {E}+sigma _{B}vec {B})</span>, with <span>(sigma _E)</span> and <span>(sigma _B)</span> being the electric and magnetic conductivities. We derive the system of equtions of the gradient expansion formalism for generic kinetic and axial coupling functions as well as Schwinger conductivities. Further, in order to test our system of equations, we apply it to a specific case of the kinetic coupling in the exponential Ratra form and the linear axial coupling function for a few benchmark points in the parameter space. To estimate the accuracy of the obtained numerical results, we perform a comparison with the results of mode-by-mode solution in the Fourier space. We show that the backreaction causes a noticeable increase in the duration of the inflationary epoch while the Schwinger effect strongly suppresses the produced electromagnetic fields and lifts their backreaction.\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"85 5","pages":""},"PeriodicalIF":4.2,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-025-14269-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143938391","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}

{"title":"Integrability aspects, Wronskian solution, Grammian solution, lump and lump-multi-kink solutions of an extended ((3+1))-dimensional Bogoyavlensky-Konopelchenko equation","authors":"Uttam Kumar Mandal,&nbsp;Sukanya Dutta,&nbsp;Wen-Xiu Ma,&nbsp;Amiya Das","doi":"10.1140/epjp/s13360-025-06273-5","DOIUrl":"10.1140/epjp/s13360-025-06273-5","url":null,"abstract":"<div><p>In this article, we examine an extended <span>((3+1))</span>-dimensional Bogoyavlensky-Konopelchenko equation, which models the interaction between a Riemann wave and a long wave in a fluid. This equation has significant applications in the study of shallow-water waves, ion-acoustic waves, and water propagation in liquids. We explore the integrability of this model through various approaches. First, we derive the Hirota bilinear form using the Bell polynomial theory. By decoupling the two-field condition, we calculate the bilinear Bäcklund transformation. Subsequently, through the Cole–Hopf transformation and the linearization of the Bäcklund transformation, we obtain the Lax pair. Additionally, we derive infinitely many conservation laws using Bell polynomial theory. We compute one-, two-, and three-soliton solutions directly from the Hirota bilinear form and present their 3-D plot, density plot and 2D plot graphically. We establish the Wronskian condition by employing the Plücker relation, ensuring that the N-soliton solutions of the equation can be represented as Wronskian determinants. Additionally, the use of a suitable transformation and the Wronskian determinant condition in our model establishes the widely known Wronskian solution to the <span>((1+1))</span>-dimensional KdV equation. We derive a rational Wronskian solution by selecting a specific coefficient matrix in the resulting Wronskian formulation. Furthermore, we calculate one-, two-, and three-soliton solutions in Wronskian form and visually depict their soliton dynamics using Mathematica with appropriately chosen parameters. Additionally, we present a Grammian determinant solution, utilizing the Jacobi relation. To obtain the lump solution, we employ a quadratic function as a test function within the Hirota bilinear form. Furthermore, we calculate two sets of lump-multi-kink solutions employing two distinct test functions. We provide a visual comparison of the evolutionary dynamics of the lump-multi-kink solutions corresponding to two distinct test functions.</p></div>","PeriodicalId":792,"journal":{"name":"The European Physical Journal Plus","volume":"140 5","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143938334","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}

{"title":"Superparamagnetic heating and cytotoxicity properties of bimagnetic core-shell nanoparticles ligated with different dispersants","authors":"V. Vinodhini,&nbsp;Vembakam Vijayakanth,&nbsp;Subhashini Brahadeeswaran,&nbsp;Ramasamy Tamizhselvi,&nbsp;Krishnamoorthi Chintagumpala","doi":"10.1007/s00339-025-08578-9","DOIUrl":"10.1007/s00339-025-08578-9","url":null,"abstract":"<div><p>Heat generation by magnetic losses (hysteresis or relaxation) in magnetic nanoparticles under alternate magnetic field (AMF) have many applications in biomedical heat treatment domain. Hence localized magnetic hyperthermia was widely researched for adjunct or independent therapy and efficient drug release in cancer treatment. For this application, the main criterion is that magnetic nanoparticles should have good biocompatibility and high heating capacity for in vivo applications and use of small quantity of nanoparticles for heat generation. It is understood that magnetic heating capacity of nanoparticles depends on saturation mass magnetization (M_s), magnetic anisotropic constant (K_A), and magnetic hysteresis. Majority of researchers modified these parameters by chemical substitution, and magnetic nanoparticles volume (size) variation. Here both M_s and K_A were modified by magnetic exchange bias field in bimagnetic hard magnetic core-soft magnetic shell nanoparticles (CSNPs). Here ZnFe₂O₄ (soft magnetic) and CoFe₂O₄ (hard magnetic) based bimagnetic ZnFe₂O₄-CoFe₂O₄ (soft core-hard shell) and CoFe₂O₄-ZnFe₂O₄ (hard core-soft shell) CSNPs with average particle diameter of 11 nm were synthesized and evaluated their magnetic heating capacities and cytocompatibility at different CSNPs concentrations under AMFs. Superparamagnetic heating capacity and cytotoxicity studies on both oleic acid, and zwitterionic dopamine sulfonate (ZDS) dispersants ligated core-shell nanoparticles show good cytocompatibility and magnetic heating capacities. Among all the samples, ZnFe₂O₄-CoFe₂O₄ CSNPs at 0.5 mg/mL concentration exhibited high heating capacity of 427 W/g. All CSNPs exhibited high cytocompatibility with L929 cells in MTT assay, in 100–900 µg/mL concentration range. These CSNPs show promising candidacy for localized magnetic hyperthermia in cancer treatment.</p></div>","PeriodicalId":473,"journal":{"name":"Applied Physics A","volume":"131 6","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143938308","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study of early inflationary phase with minimal and non-minimal coupling using string-motivated potential","authors":"Chitrak Sarkar,&nbsp;Amitava Choudhuri,&nbsp;Buddhadeb Ghosh","doi":"10.1140/epjc/s10052-025-14236-4","DOIUrl":"10.1140/epjc/s10052-025-14236-4","url":null,"abstract":"<div><p>We study the early inflationary phase using a potential derived from type IIB/F theory within the frameworks of minimally and non-minimally coupled scalar fields to gravity. The well-known cosmological Klein–Gordon equation based on a single scalar field with a stringy potential is solved numerically for both setups. The solutions obtained are consistent with the Friedmann equation. We first use a solution for minimal setup to calculate some important inflationary parameters, e.g., first slow-roll parameter (<span>(epsilon )</span>), the tensor-to-scalar ratio (<i>r</i>), and the scalar spectral index (<span>(n_s)</span>) during inflation. We have found <span>(r=0.0011)</span>, and <span>(n_s= 0.9647)</span>, that lie well inside the Planck-2018 data. Specifically, we investigate a solution for a non-minimal setup to explore the non-Gaussianity. In this scenario, a conformal transformation is used to study the various inflationary parameters in the Jordan- and Einstein frames. We have calculated the potential slow-roll parameters predicting the range for <i>r</i> (<span>(0.009983,,textrm{to},, 0.00022)</span>) and <span>(n_s)</span> (<span>(0.9597,, textrm{to}, , 0.9707)</span>), which lie well within the Planck-2018 data in 68% and 95% C.L. The non-Gaussian parameters <span>({f}_{NL})</span> (<span>(-0.0167824)</span> to <span>(-0.01222)</span>), <span>({tau }_{NL})</span> (<span>(2.816times 10^{-4})</span> to <span>(1.49times 10^{-4})</span>) and <span>({g}_{NL})</span> (<span>(-2.877times 10^{-4})</span> to <span>(-1.673times 10^{-4})</span>) for non-minimal coupling constant <span>(xi )</span> ranging from 0.001 to 0.0001 with 60 e-folds are obtained. We have elucidated the graceful exit phenomenon from the inflationary phase for both setups. The application of the technique of dynamical systems analysis offers insights into the stability and the dynamic nature of the inflationary solution in the phase space, that indicates the starting and ending of the inflationary period.\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"85 5","pages":""},"PeriodicalIF":4.2,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-025-14236-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143938484","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}

{"title":"Black holes surrounded by massive vector fields in Kaluza–Klein gravity","authors":"Kimet Jusufi,&nbsp;Ankit Anand,&nbsp;Sara Saghafi,&nbsp;B. Cuadros-Melgar,&nbsp;Kourosh Nozari","doi":"10.1140/epjc/s10052-025-14253-3","DOIUrl":"10.1140/epjc/s10052-025-14253-3","url":null,"abstract":"<div><p>We present an exact black hole solution surrounded by massive vector fields predicted by Kaluza–Klein (KK) gravity. KK gravity in four dimensions (4D) is of particular interest, as it predicts a tower of particle states, including gravitons with spin-0 and spin-1 components, in addition to the massless spin-2 gravitons of general relativity. The extra degrees of freedom in the gravitational sector modify the law of gravity, allowing the theory to explain the effects attributed to dark matter in the universe. In this paper, we construct a black hole solution surrounded by massive spin-1 gravitons within KK theory. In addition to the influence of the massive vector fields, we incorporate an interaction term between the black hole and the massive vector field. The black hole solution is affected by the mass of the spin-1 graviton and an additional parameter that encodes corrections to Newton’s constant, as well as the coupling between the massive vector field and the black hole mass. We find that the coupling between the massive vector field and the black hole mimics the effect of an electric charge. To this end, we investigate the accretion disk, quasinormal modes (QNMs), and the stability of the black hole spacetime. Finally, we use Event Horizon Telescope (EHT) observations of Sgr A* to constrain the black hole parameters.\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"85 5","pages":""},"PeriodicalIF":4.2,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-025-14253-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143944361","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}

{"title":"Aspects of non-local QED and the weak gravity conjecture","authors":"Fayez Abu-Ajamieh,&nbsp;Nobuchika Okada,&nbsp;Sudhir K. Vempati","doi":"10.1140/epjc/s10052-025-14169-y","DOIUrl":"10.1140/epjc/s10052-025-14169-y","url":null,"abstract":"<div><p>We use the weak gravity conjecture (WGC) to investigate the impact of charge dequantization arising from non-local QED on the scale of non-locality of neutrinos. We find this scale to be <span>(lesssim 49)</span> TeV as implied by direct bounds and <span>(lesssim 15)</span> TeV as implied by cosmological bounds, which could be probed in future colliders. We also investigate the electric force and potential in non-local QED and use them to reformulate the weak gravity conjecture (WGC) in non-local QED.\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"85 5","pages":""},"PeriodicalIF":4.2,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-025-14169-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143944362","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}

{"title":"Charged isotropic solutions with linear barotropic equations of state in Einstein–Gauss–Bonnet gravity","authors":"Siyamthanda Remember Mngadi,&nbsp;Sudan Hansraj","doi":"10.1140/epjc/s10052-025-14265-z","DOIUrl":"10.1140/epjc/s10052-025-14265-z","url":null,"abstract":"<div><p>In the present work we investigate new class of charged isotropic solutions with a linear barotropic equation of state (EoS) in the framework of Einstein–Gauss–Bonnet (EGB) gravity for 5 and 6 dimensional spherically symmetric static distributions. Imposing such a restriction of the EoS, one more further assumption on the metric potentials must be chosen in order to close the system. For example, the constant gravitational potential which is responsible for an isothermal distribution in Einstein gravity and as well as different forms of temporal potential are analyzed. Through graphical analysis we demonstrate that the obtained exact models satisfy the basic elementary astrophysical requirement for physical plausibility.</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"85 5","pages":""},"PeriodicalIF":4.2,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-025-14265-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143938393","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}

{"title":"Clustering in nuclei and hadrons","authors":"Atsushi Hosaka,&nbsp;Yoshiko Kanada-En’yo,&nbsp;Yasuhiro Yamaguchi","doi":"10.1140/epja/s10050-025-01530-8","DOIUrl":"10.1140/epja/s10050-025-01530-8","url":null,"abstract":"<div><p>Clustering phenomena in hadron and nuclear systems are overviewed. Because the energy scales for hadron and nuclear systems are not very much different, we can apply similar ideas and methods for the study of the seemingly different two systems, with the key ingredient, cluster. Once clusters are formed, they develop low lying excitations near the threshold if suitable interaction is available. This is a universal phenomenon which has been known as the threshold-rule. For nuclear systems the most established is the alpha (<span>(alpha )</span>-)cluster which is the nucleus of <span>(^4textrm{He})</span>. How the <span>(alpha )</span>-clusters develop in nuclei of light-medium mass region, typically <span>(^{12}textrm{C})</span> is discussed in a microscopic manner based on the antisymmetrized molecular dynamics. The evidences of such clustering in some static properties of nuclei and scattering phenomena are discussed. Similar clustering phenomena occur for hadrons, where quark clusters are developed in either colored or colorless channels which are considered to play an important role for exotic hadrons of multi-quarks. In particular colorless hadronic clusters can be good constituents to form molecular-like structure near threshold regions.</p></div>","PeriodicalId":786,"journal":{"name":"The European Physical Journal A","volume":"61 5","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epja/s10050-025-01530-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143944359","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}

{"title":"Elastic and inelastic collisions in the (2 + 1)-dimensional modified dispersive water wave equation","authors":"Qing-Jiang Feng,&nbsp;Guo-Qing Zhang","doi":"10.1140/epjp/s13360-025-06322-z","DOIUrl":"10.1140/epjp/s13360-025-06322-z","url":null,"abstract":"<div><p>The research objective of this paper is to improve the <i>exp</i> [-<i>ϕ</i>(ξ)] expansion method and discuss elastic and inelastic collisions (the fusion and fission) of multiple localized waves. Based on variable separation transformation, a series of new variable separation solutions for the (2 + 1)-dimensional modified dispersive water wave equation are constructed using the improved <i>exp</i>[-<i>ϕ</i>(ξ)]] expansion method. By introducing some appropriate functions, the three-dimensional images of variable separation solutions are provided to investigate the structural characteristics and dynamic behavior of these solutions. The variable separation solutions exhibit two inelastic collisions phenomena: multiple dromion waves fuse into one dromion wave, and one periodic dromion wave splits into multiple periodic dromion waves. In addition, the “head-on” elastic collision, “chasing” elastic collision, and “head on-chasing” elastic collision of multiple periodic dromion waves are discussed, as well as the inelastic collision of two dromion solitons in a plane (on a periodic background). It is hoped that the interaction phenomenon of nonlinear waves discussed in this paper can provide a certain positive effect on the study of soliton theory.</p></div>","PeriodicalId":792,"journal":{"name":"The European Physical Journal Plus","volume":"140 5","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143938332","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}

{"title":"Plasmon-sound hybridization in ionic crystals","authors":"Jakob Rappolt,&nbsp;Andreas Rückriegel,&nbsp;Peter Kopietz","doi":"10.1140/epjb/s10051-025-00941-2","DOIUrl":"10.1140/epjb/s10051-025-00941-2","url":null,"abstract":"<p> We study the hybridization between plasmons, phonons, and electronic sound in ionic crystals using the Debye model, where the ionic background is modeled as a homogeneous, isotropic, elastic medium. We explicitly obtain the energies and the damping of the hybrid plasmon-sound modes in the hydrodynamic regime and calculate the corresponding dynamic structure factor. We find that with increasing viscosity, a plasmon-like mode quickly decays into a broad, incoherent background, while a phonon-like mode with linear dispersion remains rather sharp. The quantitative behavior of the hybridized collective modes depends on the ratio of the electronic and the ionic plasma frequencies. We also show that the direct Coulomb interaction between the ions is essential to obtain a collective sound mode with linear dispersion.</p>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"98 5","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjb/s10051-025-00941-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143938616","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}