The European Physical Journal C最新文献

{"title":"Electron-positron pair creation under Gaussian and super-Gaussian pulse trains","authors":"X. X. Zhou,&nbsp;X. N. Cao,&nbsp;C. K. Li,&nbsp;N. S. Lin,&nbsp;Y. J. Li","doi":"10.1140/epjc/s10052-024-13453-7","DOIUrl":"10.1140/epjc/s10052-024-13453-7","url":null,"abstract":"<div><p>The electron-positron pair (EPP) creation under Gaussian and super-Gaussian pulse trains are studied by the computational quantum field theory (CQFT) in the single-photon regime. The details of the EPP creation are studied from the time evolution of the EPP number, energy spectra and spatial distribution of the electrons. The results indicate that the final created EPPs is the non-linear accumulation of the multi-pulses, which depends on the time interval, pulse shape and pulse number. The optimal time interval can be chosen based on the pulse resonance condition, which is derived by the perturbation method. Besides, steeper super-Gaussian pulses and adding more pulses facilitate the EPP creation as well. The results indicate that, under optimal multi-pulse parameters, the number of the EPPs obtained is much larger than the sum of the EPPs created under the same number of single pulses. This finding not only can enhance the EPP creation, but also can improve the multi-pulse utilization and guide future experimental research on the EPP creation.</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"84 10","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-024-13453-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142519142","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":"Time dependent black holes and gravitational wave in Einstein–Gauss–Bonnet theory with two scalar fields","authors":"G. G. L. Nashed","doi":"10.1140/epjc/s10052-024-13441-x","DOIUrl":"10.1140/epjc/s10052-024-13441-x","url":null,"abstract":"<div><p>In this paper, we investigate the time dependent black holes in the frame of Einstein–Gauss–Bonnet theory having two scalar fields and investigate the propagation of the gravitational wave (GW). In the reconstructed models, there often appear ghosts, which could be eliminated by imposing some constraints. We investigate the behavior of high-frequency gravitational waves by examining the effects of varying Gauss–Bonnet coupling during their propagation. The speed of propagation changes due to the coupling during the black hole formation process. The propagation speed of gravitational waves differs when they enter the black hole compared to when they exit.</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"84 10","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-024-13441-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142524508","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":"Non-parametric reconstruction of the fine structure constant with galaxy clusters","authors":"Marcelo Ferreira,&nbsp;Rodrigo F. L. Holanda,&nbsp;Javier E. Gonzalez,&nbsp;L. R. Colaço,&nbsp;Rafael C. Nunes","doi":"10.1140/epjc/s10052-024-13468-0","DOIUrl":"10.1140/epjc/s10052-024-13468-0","url":null,"abstract":"<div><p>Testing possible variations in fundamental constants of nature is a crucial endeavor in observational cosmology. This paper investigates potential cosmological variations in the fine structure constant (<span>(alpha )</span>) through a non-parametric approach, using galaxy cluster observations as the primary cosmological probe. We employ two methodologies based on galaxy cluster gas mass fraction measurements derived from X-ray and Sunyaev–Zeldovich observations, along with luminosity distances from type Ia supernovae. We also explore how different values of the Hubble constant (<span>(H_0)</span>) impact the variation of <span>(alpha )</span> across cosmic history. When using the Planck satellite’s <span>(H_0)</span> observations, a constant <span>(alpha )</span> is ruled out at approximately the 3<span>(sigma )</span> confidence level for <span>(z lesssim 0.5)</span>. Conversely, employing local estimates of <span>(H_0)</span> restores agreement with a constant <span>(alpha )</span>.</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"84 10","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-024-13468-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142524510","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":"Egg-shaped sections of fluid structures around black holes","authors":"Abylaikhan Tlemissov,&nbsp;Jiří Kovář","doi":"10.1140/epjc/s10052-024-13496-w","DOIUrl":"10.1140/epjc/s10052-024-13496-w","url":null,"abstract":"<div><p>Astrophysical fluids subjected to the strong gravity of black holes can form rotating toroidal-like structures known as thick accretion discs. In order to facilitate the study of such structures, we introduce approximate empirical formulae for a relatively simple analytical description of their poloidal cross-sections that are usually described only numerically. Our comparisons of the approximate and exact descriptions of the cross-sections of the structures rotating around Schwarzschild and Kerr central black holes, together with the determination of the associated total masses of these structure, indicate a high degree of accuracy for these introduced formulae.</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"84 10","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-024-13496-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142518918","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":"QPOs from charged particles around magnetized black holes in braneworlds","authors":"Javlon Rayimbaev,&nbsp;Sardor Murodov,&nbsp;Abubakir Shermatov,&nbsp;Amirkhon Yusupov","doi":"10.1140/epjc/s10052-024-13463-5","DOIUrl":"10.1140/epjc/s10052-024-13463-5","url":null,"abstract":"<div><p>Quasiperiodic oscillations (QPOs) are a powerful tool for testing gravity theories, probing gravitational and electromagnetic field properties, and obtaining constraints on the black hole and field parameters. This work considers charged particle dynamics near uniformly magnetized black holes in braneworlds. First, we obtain the solution of the Maxwell equation for magnetic fields and calculate the radial and angular magnetic field components. We derive and analyze the effective potential of charged particles for circular orbits and investigate the energy and angular momentum for the circular orbits. We also analyze the combined effects of magnetic interaction and braneworlds on the charged particles’ innermost stable circular orbits (ISCOs). We calculate the angular momentum of charged particles in Keplerian orbits in the presence of an external magnetic field and braneworlds. Also, we investigate frequencies of the particle oscillations along vertical and angular directions. We applied our studies on particle oscillations to the QPO studies in the relativistic precession model. Finally, we obtain constraints on magnetic interaction and braneworld parameters together with the black hole mass and QPO orbits using Monte Carlo Markov Chain (MCMC) simulation in the four-dimensional parameter space for the QPOs observed in the microquasars XTE J1550-564, GRO J1655-40 &amp; GRS 1915-105, and at the center of galaxies M82 and Milky Way.</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"84 10","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-024-13463-5.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142518917","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":"Quantum nature of black hole and the superposition of fermionic field","authors":"Jinshan An,&nbsp;Li Zhang,&nbsp;Lulu Xiao,&nbsp;Jieci Wang","doi":"10.1140/epjc/s10052-024-13483-1","DOIUrl":"10.1140/epjc/s10052-024-13483-1","url":null,"abstract":"<div><p>The operational framework for the superposition of spacetime is fundamentally important in developing a comprehensive description of quantum gravity (Foo et al. in Phys Rev Lett 129:181301, 2022). As a “bottom-up” unifying theory of quantum gravity, it allows us to investigate how mass superposition of spacetime influences the performance of quantum information processing. In this paper, we study how the quantum-gravitational effects produced by the mass superposition of a black hole influence the quantum coherence of fermionic fields. It is shown that the spacetime effects associated with a classical black hole lead to inevitable decoherence. Notably, compared to classical black hole spacetime scenarios, fermionic fields near a black hole with superposed masses can retain more quantum coherence. This suggests that the quantum properties of spacetime may serve as resources to mitigate coherent degradation caused by gravitational effects. The bottom-up perspective on spacetime superposition proposed in this work serves as an indication of quantum-gravitational effects and holds significant theoretical implications.</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"84 10","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-024-13483-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142518602","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":"Influence of field mass and acceleration on entanglement generation","authors":"Yongjie Pan,&nbsp;Jiatong Yan,&nbsp;Sansheng Yang,&nbsp;Baocheng Zhang","doi":"10.1140/epjc/s10052-024-13488-w","DOIUrl":"10.1140/epjc/s10052-024-13488-w","url":null,"abstract":"<div><p>We explore the entanglement dynamics of two detectors undergoing uniform acceleration and circular motion within a massive scalar field, while also investigating the influence of the anti-Unruh effect on entanglement harvesting. Contrary to the conventional understanding of the weak anti-Unruh effect, where entanglement typically increases, we observe that the maximum entanglement between detectors does not exhibit a strict monotonic dependence on detector acceleration. Particularly at low accelerations, fluctuations in the entanglement maxima show a strong correlation with fluctuations in detector transition rates. We also find that the maximum entanglement of detectors tends to increase with smaller field mass. Novelly, our findings indicate the absence of a strong anti-Unruh effect in (3+1)-dimensional massive scalar fields. Instead, thermal effects arising from acceleration contribute to a decrease in the detector entanglement maximum.</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"84 10","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-024-13488-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142519025","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":"Complexity characterization in modeling anisotropic compact stellar structures","authors":"Shyam Das,&nbsp;Megandhren Govender,&nbsp;Somi Aktar","doi":"10.1140/epjc/s10052-024-13439-5","DOIUrl":"10.1140/epjc/s10052-024-13439-5","url":null,"abstract":"<div><p>In this study, we present an exact solution to the Einstein field equations, featuring a static, spherically symmetric, anisotropic compact stellar fluid sphere with non-zero complexity. The model is constructed using a specific metric potential for the <span>(g_{tt})</span> component, along with a defined complexity profile. The model parameters are fixed by ensuring the continuity of the interior and exterior metrics across the surface of the star and by setting the radial pressure to zero across the boundary. The stability of the model has been analyzed by verification of different standard conditions. Validation of our model is supported by recent observational data from well-known pulsars.</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"84 10","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-024-13439-5.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142518806","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":"Study of the axial-vector and tensor resonant contributions to the (D rightarrow VPell ^+nu _ell ) decays based on SU(3) flavor analysis","authors":"Yi Qiao,&nbsp;Yue-Xin Liu,&nbsp;Yuan-Guo Xu,&nbsp;Ru-Min Wang","doi":"10.1140/epjc/s10052-024-13387-0","DOIUrl":"10.1140/epjc/s10052-024-13387-0","url":null,"abstract":"<div><p>Semileptonic three-body <span>(D rightarrow Mell ^+nu _ell )</span> decays, non-leptonic <span>(M rightarrow VP)</span> decays, and semileptonic four-body <span>(D rightarrow M(M rightarrow VP)ell ^+nu _ell )</span> decays are analyzed using the SU(3) flavor symmetry/breaking approach, where <span>(ell =e/mu )</span>, <span>(M=A/T)</span>, and <i>A</i>/<i>T</i>/<i>V</i>/<i>P</i> denote the axial-vector/tensor/vector/pseudoscalar mesons, respectively. In terms of SU(3) flavor symmetry/breaking, the decay amplitudes of the <span>(D rightarrow M ell ^+ nu _ell )</span> decays and the vertex coefficients of the <span>(M rightarrow VP)</span> decays are related. The relevant non-perturbative parameters of the <span>(D rightarrow Aell ^+nu _ell )</span>, <span>(A rightarrow VP)</span>, and <span>(T rightarrow VP)</span> decays are constrained by the present experimental data, and the non-perturbative parameters of <span>(D rightarrow Tell ^+nu _ell )</span> decays are taken from the results in the light-front quark model since no experimental data are available at present. The branching ratios of the <span>(D rightarrow M ell ^+ nu _ell )</span>, <span>(M rightarrow VP)</span>, and <span>(Drightarrow M(Mrightarrow VP)ell ^+nu _ell )</span> decays are then predicted. We find that some processes receive both tensor and axial-vector resonant contributions, while other processes receive only axial-vector resonant contributions. In cases where both kinds of resonant contributions exist, the axial-vector contributions are dominant. Some branching ratios with axial-vector resonance states are large, and they may be measured experimentally in the near future. In addition, the sensitivities of the branching ratios of <span>(D rightarrow A ell ^+ nu _ell )</span> and <span>(A rightarrow VP)</span> decays to the parameters are also investigated, and some decay branching ratios are found to be sensitive to the non-perturbative parameters.</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"84 10","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-024-13387-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142518714","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":"D-Brane effective Lagrangian in spacetimes with boundaries","authors":"Ali Baradaran-Hosseini,&nbsp;Mohammad R. Garousi","doi":"10.1140/epjc/s10052-024-13399-w","DOIUrl":"10.1140/epjc/s10052-024-13399-w","url":null,"abstract":"<div><p>In this study, we explore the transformation of <span>(D_p)</span>-branes to <span>(D_{p-1})</span>-branes under T-duality when the <i>D</i>-brane is embedded in a spacetime with a boundary. Our goal is to derive the higher-derivative corrections to the Dirac–Born–Infeld (DBI) Lagrangian for both the bulk and boundary terms. For the bulk terms, we calculate the <span>(alpha ')</span> corrections for the massless open string fields, up to the 8th order in the dimensionless Maxwell field strength. We demonstrate that the bulk Lagrangian can satisfy the T-duality constraint without residual total derivative terms in the base space. This determines the most general independent couplings of the massless open string fields in the bulk Lagrangian, encompassing 145 coupling constants, up to three parameters. Two of these parameters are physical and are determined by disk-level S-matrix elements, while the third is unphysical and can be eliminated by field redefinitions and integration by parts. The final result for the bulk Lagrangian consists of 49 couplings. For the boundary terms, the application of T-duality symmetry to massless open and closed string fields enables us to extend the DBI Lagrangian to include the boundary unit normal vector field <span>(n_mu )</span> and its first derivative.</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"84 10","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-024-13399-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142519009","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}