物理最新文献

{"title":"Novel Casimir wormholes in Einstein gravity","authors":"Mohammad Reza Mehdizadeh,&nbsp;Amir Hadi Ziaie","doi":"10.1140/epjp/s13360-024-05801-z","DOIUrl":"10.1140/epjp/s13360-024-05801-z","url":null,"abstract":"<div><p>In the context of General Relativity (GR), violation of the null energy condition (NEC) is necessary for existence of static spherically symmetric wormhole solutions. Also, it is a well-known fact that the energy conditions are violated by certain quantum fields, such as the Casimir effect. The magnitude and sign of the Casimir energy depend on Dirichlet or Neumann boundary conditions and geometrical configuration of the objects involved in a Casimir setup. The Casimir energy may act as an ideal candidate for the matter that supports the wormhole geometry. In the present work, we firstly find traversable wormhole solutions supported by a general form for the Casimir energy density assuming a constant redshift function. As well, in this framework, assuming that the radial pressure and energy density obey a linear equation of state, we derive for the first time Casimir traversable wormhole solutions admitting suitable shape function. Then, we consider three geometric configurations of the Casimir effect such as (i) two parallel plates, (ii) two parallel cylindrical shells, and (iii) two spheres. We study wormhole solutions for each case and their property in detail. We also check the weak and strong energy conditions in the spacetime for the obtained wormhole solutions. The stability of the Casimir traversable wormhole solutions are investigated using the Tolman-Oppenheimer-Volkoff (TOV) equation. Finally, we study trajectory of null as well as timelike particles along with quasi-normal modes (QNMs) of a scalar field in the wormhole spacetime.</p></div>","PeriodicalId":792,"journal":{"name":"The European Physical Journal Plus","volume":"139 11","pages":""},"PeriodicalIF":2.8,"publicationDate":"2024-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142645404","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":"Antiproton annihilation at rest in thin solid targets and comparison with Monte Carlo simulations","authors":"C. Amsler,&nbsp;H. Breuker,&nbsp;M. Bumbar,&nbsp;M. Cerwenka,&nbsp;G. Costantini,&nbsp;R. Ferragut,&nbsp;M. Fleck,&nbsp;M. Giammarchi,&nbsp;A. Gligorova,&nbsp;G. Gosta,&nbsp;E. D. Hunter,&nbsp;C. Killian,&nbsp;B. Kolbinger,&nbsp;V. Kraxberger,&nbsp;N. Kuroda,&nbsp;M. Lackner,&nbsp;M. Leali,&nbsp;G. Maero,&nbsp;V. Mascagna,&nbsp;Y. Matsuda,&nbsp;S. Migliorati,&nbsp;D. J. Murtagh,&nbsp;A. Nanda,&nbsp;L. Nowak,&nbsp;S. Rheinfrank,&nbsp;M. Romé,&nbsp;M. C. Simon,&nbsp;M. Tajima,&nbsp;V. Toso,&nbsp;S. Ulmer,&nbsp;M. van Beuzekom,&nbsp;L. Venturelli,&nbsp;A. Weiser,&nbsp;E. Widmann,&nbsp;Y. Yamazaki,&nbsp;J. Zmeskal","doi":"10.1140/epja/s10050-024-01428-x","DOIUrl":"10.1140/epja/s10050-024-01428-x","url":null,"abstract":"<div><p>The mechanism of antiproton–nucleus annihilation at rest is not fully understood, despite substantial previous experimental and theoretical work. In this study we used slow extracted antiprotons from the ASACUSA apparatus at CERN to measure the charged particle multiplicities and their energy deposits from antiproton annihilations at rest on three different nuclei: carbon, molybdenum and gold. The results are compared with predictions from different models in the simulation tools Geant4 and FLUKA. A model that accounts for all the observed features is still missing, as well as measurements at low energies, to validate such models.</p></div>","PeriodicalId":786,"journal":{"name":"The European Physical Journal A","volume":"60 11","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epja/s10050-024-01428-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142664477","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":"Borosilicate glasses doped with Er2O3: preparation, physical, optical, dielectric properties and radiation shielding capacity","authors":"Aljawhara Almuqrin,&nbsp;Jamelah S. Al-Otaibi,&nbsp;Norah Alwadai,&nbsp;Badriah Albarzan,&nbsp;R. A. Elsad,&nbsp;M. S. Shams,&nbsp;Yasser S. Rammah","doi":"10.1007/s00339-024-08071-9","DOIUrl":"10.1007/s00339-024-08071-9","url":null,"abstract":"<div><p>This study aimed to investigate the physical, optical, dielectric properties as well as gamma-ray shielding capacity of borosilicate glass samples with chemical formula 70B₂O₃–5SiO₂–10Li₂O–5Bi₂O₃–10ZnO–XEr₂O₃ with X = 0.0 (Er-0.0) to 1.2 (Er-1.2) mol% which prepared by the melt quenching technique method. Densities (D_s) of Er-X samples increased from 2.95 to 3.12 g/cm³, whereas the molar volume (V_m) declined from 30.68 to 30.50 cm³/mol as Er₂O₃ content increased from 0.0 to 1.2 mol%. The oxygen packing density (OPD) enhanced from 89.64 to 90.33 mol/l, whereas oxygen molar volume (OMV) decreased from 11.16 to 10.95 cm³/mol. The optical band gap decreased from 3.36 to 2.90 eV for direct transition, while decreased from 2.96 to 2.50 eV for indirect transition. Urbach energy (ΔE_u) was enhanced from 0.17 to 0.56 eV. The refractive index (n) was increased from 2.40 to 2.54. The dielectric constant regularly rises with increasing Er₂O₃ content in the glass networks. The mass attenuation coefficient (MAC) followed the trend as (Er-1.2)_MAC &gt; (Er-0.9)_MAC &gt; (Er-0.6)_MAC &gt; (Er-0.3)_MAC &gt; (Er-0.0)_MAC. The Er-1.2 sample possessed the lowest values of half value layer (HVL) and mean free path (MFP). Results showed that suggested Er-X glasses, can be used in optical and radiation shielding applications.</p></div>","PeriodicalId":473,"journal":{"name":"Applied Physics A","volume":"130 12","pages":""},"PeriodicalIF":2.5,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142645662","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":"Interacting topological quantum aspects with light and geometrical functions","authors":"Karyn Le Hur","doi":"10.1016/j.physrep.2024.11.003","DOIUrl":"10.1016/j.physrep.2024.11.003","url":null,"abstract":"<div><div>I review my recent progress and develop a geometrical approach in the quantum with light as a guide, from the vector potential in classical physics, revealing that topological properties can be equivalently measured from the poles of a sphere. The topological state is induced on the Bloch sphere of a spin-1/2 particle from a radial magnetic field related to the physics of Skyrmions. This shows a relation between the global topological response being measured at the poles, the response to a circularly polarized field and the quantum metric. I show how this approach is helpful for the classification of matter with the detection of the global topological invariant at specific points in the Brillouin zone, e.g. the Dirac points, from the responses to electromagnetic waves such as circularly polarized light and from new geometrical functions associated to the quantum metric measuring the quantum Hall and spin Hall conductivities. The <span><math><mi>M</mi></math></span> point associated to the Brillouin zone of the honeycomb lattice also reveals the topological signature. Interactions are included in momentum space within a stochastic variational approach. In a realistic quantum model of interacting spins, this leads to fractional topological entangled aspects with a correspondence between a pair of half invariants and a Einstein–Podolsky–Rosen (EPR) pair or Bell state at one pole. I also formulate a correspondence between fractional topological numbers and resonating valence bond states. This approach gives further insight on the characterization of topological matter linked to superconductivity, protected topological semimetals in two dimensions and on the search of Majorana fermions for topologically protected quantum information. We also address a correspondence with the fractional quantum Hall effect and surface states of three-dimensional topological insulators.</div></div>","PeriodicalId":404,"journal":{"name":"Physics Reports","volume":"1104 ","pages":"Pages 1-42"},"PeriodicalIF":23.9,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142657528","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Higher order approximations in quantum speed limit time of a qubit coupled to XXZ spin chain environment","authors":"Muhammad Musadiq,&nbsp;Mehvish Shahzadi,&nbsp;Salman Khan","doi":"10.1140/epjp/s13360-024-05815-7","DOIUrl":"10.1140/epjp/s13360-024-05815-7","url":null,"abstract":"<div><p>The quantum speed limit (QSL) time of a single qubit coupled to Heisenberg <i>XXZ</i> spin bath is investigated. The time convolutionless (TCL) projection operators technique is followed for investigating the second (TCL2), third (TCL3) and fourth (TCL4) order approximations in QSL time of centrally interacting qubit. The results are discussed up to fourth order of perturbation expansions of the non-Markovian master equation of motion. Behavior of QSL time is studied against temperature, interaction time and coupling strength for second, third and fourth orders of master equation using TCL technique. The behavior of QSL time becomes less perturbative for third and fourth order approximations as compared to second order. It is investigated that QSL time of qubit becomes constant very quickly in the low temperature limit for third and fourth order approximation, which means evolution speed of qubit is less affected for higher orders of approximations. QSL time for third and fourth orders of TCL gives much better results at high temperature and also behave well at short times. It is observed that, as the order of the TCL master equation increases, the accuracy of the approximation improves, but the complexity of the equation also increases due to involvement of more and more interaction terms in the TCL master equation.</p></div>","PeriodicalId":792,"journal":{"name":"The European Physical Journal Plus","volume":"139 11","pages":""},"PeriodicalIF":2.8,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142645695","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":"Quantum dense coding in two-qubit anisotropic XY Heisenberg model with Herring-Flicker coupling","authors":"Pouyan Ghiasi,&nbsp;Somayyeh Ghorbani,&nbsp;Seyed Mohammad Hosseiny,&nbsp;Milad Norouzi,&nbsp;Razie Mohebbi,&nbsp;Jamileh Seyed-Yazdi","doi":"10.1007/s00340-024-08346-2","DOIUrl":"10.1007/s00340-024-08346-2","url":null,"abstract":"<div><p>Quantum dense coding enables the transmission of two bits of classical information using a single qubit, leveraging the initial maximal entanglement of a Bell state channel. This study investigates this process within a two-qubit anisotropic XY Heisenberg spin chain, influenced by Herring-Flicker coupling and subjected to an external magnetic field. In practical scenarios, the interaction between spins, characterized by the variable coupling strength <i>J</i>, significantly impacts the assessment of these spin systems for quantum computing and communication. Therefore, it is essential to consider the distance between the spins. This article aims to analyze the effects of temperature variations on the quantum communication channel, taking into account Herring-Flicker coupling, which is vital for implementing quantum communication protocols in real-world applications. Our findings suggest that the current channel shows promising potential for the quantum-dense coding protocol.</p></div>","PeriodicalId":474,"journal":{"name":"Applied Physics B","volume":"130 12","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142645660","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":"Anisotropic stellar modeling via MIT Bag model EoS admitting Finch–Skea spacetime in f(Q) gravity","authors":"Allah Ditta,&nbsp;Munaza Asia,&nbsp;Abdelghani Errehymy,&nbsp;G. Mustafa,&nbsp;S. K. Maurya,&nbsp;Asif Mahmood","doi":"10.1140/epjp/s13360-024-05778-9","DOIUrl":"10.1140/epjp/s13360-024-05778-9","url":null,"abstract":"<div><p>This study evaluates the viability and stability of anisotropic compact stellar objects by utilizing the Finch–Skea spacetime solutions in <i>f</i>(<i>Q</i>) gravity, where <i>Q</i> is a nonmetricity scalar that incorporates gravitational effects. The physical properties of the compact star EXO 1785-248 are investigated by employing a static spherical metric in the inner region and Schwarzschild spacetime in the outer region. The unknown parameters are determined using observed values of the radius and mass of the studied compact star. The suggested mass and radius values of EXO 1785-248 from existing literature are utilized. Subsequently, calculations are conducted to determine the essential features of the compact star and establish its stability and physical existence. Various aspects are analyzed, including energy density, pressure profiles, gradients, anisotropic factors, energy conditions, sound speeds, Tolman–Oppenheimer–Volkoff forces, equation of state components, mass function, compactification, and redshift, in order to achieve this objective.</p></div>","PeriodicalId":792,"journal":{"name":"The European Physical Journal Plus","volume":"139 11","pages":""},"PeriodicalIF":2.8,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142645696","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":"An empirical formula for the proton radioactivity","authors":"Jie-Dong Jiang,&nbsp;Xiao Liu,&nbsp;Yang-yang Xu,&nbsp;Biao He,&nbsp;Xi-Jun wu,&nbsp;Xiao-Hua Li","doi":"10.1140/epja/s10050-024-01443-y","DOIUrl":"10.1140/epja/s10050-024-01443-y","url":null,"abstract":"<div><p>Proton radioactivity is an exotic decay mode of proton-rich nuclei far from the <span>(beta )</span>-stability line and shares the similar decay mechanism theory of barrier penetration as <span>(alpha )</span> decay. In present work, we extend the Hatsukawa formula (Hatsukawa et al. in Phys Rev C 42:674, 1990) for <span>(alpha )</span> decay to proton radioactivity and propose an empirical formula for evaluating the proton radioactivity half-lives of proton nuclei with Z  &gt;  68. Using this formula, we systematically calculate the proton radioactivity half-lives of 33 spherical proton emitters with the corresponding root-mean-square (rms) deviation being 0.391. It is found that the calculated half-lives can reproduce the experimental data well. Moreover, we extend this formula to predict the proton radioactivity half-lives of 18 spherical proton emitters, whose proton radioactivity is energetically allowed or observed but not yet quantified. For comparison, unified fission model (UFM), Coulomb potential and proximity potential model (CPPM), universal decay law for proton emission (UDLP) and new Geiger-Nuttall law (NG-N) are also used. All the predictions are basically consistent with each other.</p></div>","PeriodicalId":786,"journal":{"name":"The European Physical Journal A","volume":"60 11","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142645698","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":"Labeling small-degree nodes promotes semi-supervised community detection on graph convolutional network","authors":"Yu Zhao,&nbsp;Huiyao Li,&nbsp;Bo Yang","doi":"10.1140/epjb/s10051-024-00817-x","DOIUrl":"10.1140/epjb/s10051-024-00817-x","url":null,"abstract":"<p>Community structure is one of the most important characteristics of network, which can reveal the internal organization structure of nodes. Many algorithms have been proposed to identify community structures in networks. However, the classification accuracy of existing unsupervised community detection algorithms is generally low. Therefore, the semi-supervised community detection algorithm which can greatly improve the classification accuracy by introducing a small number of labeled nodes has attracted much attention. Nevertheless, previous studies were sketchy in terms of label rates and also ignored the variation of classification accuracy under different labeling strategies. In this paper, based on graph convolutional networks, we first study the effect of labeling strategies and label rates on classification accuracy in four real world networks in detail. The research phenomenon is counter-intuitive but surprisingly effective: the classification accuracy of labeling small-degree nodes or random-selection nodes is significantly higher than that of labeling high-degree nodes. The labeling strategies based on acquaintance immune algorithm also prove this result. The interesting question that arises is what topological properties of the network can lead to such results? So we test and verify it in two kinds of synthetic networks. It is found that the phenomenon which labeling small-degree nodes promotes classification accuracy can be observed when the degree distribution of the network follows power-law distribution and the ratio of the external edges of the community to the total edges of nodes in the network is small.</p>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"97 11","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142645758","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}

{"title":"Anisotropic gravastar as horizonless regular black hole spacetime and its images illuminated by thin accretion disk","authors":"M. F. Fauzi,&nbsp;H. S. Ramadhan,&nbsp;A. Sulaksono","doi":"10.1140/epjc/s10052-024-13519-6","DOIUrl":"10.1140/epjc/s10052-024-13519-6","url":null,"abstract":"<div><p>A connection between regular black holes and horizonless ultracompact objects was proposed in Carballo-Rubio et al. (JHEP 08:046, 2023, arXiv:2211.05817 [gr-qc]). In this paper, we construct a model of a horizonless compact object, specifically an anisotropic gravastar with continuous pressure, that corresponds to regular black hole spacetime in the appropriate limit. The construction begins by modeling an equation of state that satisfies the anisotropic gravastar conditions and transitions to the de Sitter (<span>(p=-epsilon )</span>) upon horizon formation. The spacetime structure is similar to the <i>Quantum Horizonless Compact Object</i> (QHCO) described in Chen and Yokokura (Phys Rev D 109:104058, 2024, arXiv:2403.09388 [gr-qc]). Within this model, we also generate images of the corresponding objects surrounded by a thin accretion disk. The resulting images reveal that assuming that the emitting matter exists only outside the object, the inner light ring structure closely resembles that of the horizonless configuration of a regular black hole and the QHCO, yet it exhibits a distinct light ring structure compared to the thin-shell gravastar model. However, the opposite occurs when emitting matter is taken into account inside the object.</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"84 11","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-024-13519-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142636767","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}