Annals of Physics最新文献

{"title":"Effective Pressure of the FRW Universe","authors":"Shi-Bei Kong","doi":"10.1016/j.aop.2025.170163","DOIUrl":"10.1016/j.aop.2025.170163","url":null,"abstract":"<div><div>In this paper, we study the effective pressure of the <span><math><mi>N</mi></math></span>-dimensional FRW(Friedmann–Robertson– Walker) universe in Einstein gravity, Gauss–Bonnet gravity, and Lovelock gravity. The effective pressure is defined by <span><math><mrow><msub><mrow><mi>P</mi></mrow><mrow><mi>e</mi><mi>f</mi><mi>f</mi></mrow></msub><mo>≔</mo><mo>−</mo><mi>d</mi><mi>E</mi><mo>/</mo><mi>d</mi><mi>V</mi></mrow></math></span>, where <span><math><mrow><mi>E</mi><mo>=</mo><mi>ρ</mi><mi>V</mi></mrow></math></span> is the effective energy and <span><math><mi>V</mi></math></span> is the volume of the FRW universe inside the apparent horizon. The effective pressure in Einstein gravity is always negative and its absolute value decreases with the horizon radius <span><math><msub><mrow><mi>R</mi></mrow><mrow><mi>A</mi></mrow></msub></math></span>. The effective pressure in Gauss–Bonnet gravity is different with the one in Einstein gravity only when <span><math><mrow><mi>N</mi><mo>≥</mo><mn>6</mn></mrow></math></span>, and in this case, the effective pressure is not always negative and has a minimum, which is very similar to the potential between molecules. The effective pressure in Lovelock gravity can have multiple zero-points and extreme points. The effective pressure in different dimensions has interesting relations. We also find that under certain condition, the effective pressure is equivalent with the ‘ordinary’ pressure <span><math><mi>p</mi></math></span> of the perfect fluid, and this condition do not depend on the specific choice of gravitational theories.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"481 ","pages":"Article 170163"},"PeriodicalIF":3.0,"publicationDate":"2025-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144757234","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":"Fokker–Planck equation for the Brownian motion in the post-Newtonian approximation","authors":"Gilberto M. Kremer","doi":"10.1016/j.aop.2025.170153","DOIUrl":"10.1016/j.aop.2025.170153","url":null,"abstract":"<div><div>A mixture of light-gas particles and Brownian heavy particles is analyzed within the framework of a post-Newtonian Boltzmann equation to determine the Fokker–Planck equation for the Brownian motion. For each species, the equilibrium distribution function refers to the corresponding post-Newtonian Maxwell–Jüttner distribution function. The expressions for the friction viscous coefficient in the first and second post-Newtonian approximations are determined, and we show their dependence on the corresponding gravitational potentials. A linear stability analysis in the Newtonian and post-Newtonian Fokker–Planck equations for the Brownian motion is developed, where the perturbations are assumed to be plane harmonic waves of small amplitudes. From a dispersion relation it follows that: (i) for perturbation wavelengths smaller than the Jeans wavelength two propagating modes – corresponding to harmonic waves in opposite directions – and one mode that does not propagate show up; (ii) for perturbation wavelengths bigger than the Jeans wavelength the time evolution of the perturbation corresponds to a growth or a decay and the one which grows refers to the instability.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"481 ","pages":"Article 170153"},"PeriodicalIF":3.0,"publicationDate":"2025-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144748786","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":"Investigation of intrinsic nonlinear effects in driven-dissipative optomechanical systems using the generalized linear response theory","authors":"B. Askari,&nbsp;A. Dalafi,&nbsp;M.J. Kazemi","doi":"10.1016/j.aop.2025.170157","DOIUrl":"10.1016/j.aop.2025.170157","url":null,"abstract":"<div><div>In this article, we study the effects of intrinsic nonlinear optomechanical interaction on the linear response of a driven-dissipative optomechanical system to a weak time-dependent perturbation. By calculating the linear response of the cavity optical mode to a weak probe laser in the framework of the generalized linear response theory, it is shown how the Stokes and anti-Stokes sideband amplitudes as well as the power reflection coefficient, and the density of states of the cavity optical mode are expressed in terms of photonic retarded Green’s functions. Then, we derive the equations of motion of retarded Green’s functions of the system from nonlinear quantum Langevin equations and solve them. It is shown that for a single-photon optomechanical coupling of the order of the cavity linewidth, the nonlinear effect does not manifest itself unless the system satisfies a resonance condition, where the frequency of the upper normal mode of the system is twice that of the lower one. Based on the generality of the present approach which works at all regimes, the validity of linearization approximation is also confirmed at the off-resonance regime.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"481 ","pages":"Article 170157"},"PeriodicalIF":3.0,"publicationDate":"2025-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144739517","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":"Probabilistic pathways: New frontiers in quantum ensemble control","authors":"Abdessamad Belfakir ,&nbsp;Randa Herzallah","doi":"10.1016/j.aop.2025.170158","DOIUrl":"10.1016/j.aop.2025.170158","url":null,"abstract":"<div><div>In this paper, we propose a novel probabilistic control framework for efficiently controlling an ensemble of quantum systems that can also compensate for the interaction of the systems with the external environment. The main challenge in this problem is to simultaneously steer an ensemble of systems with variation in their internal parameters from an initial state to a desired final state. The minimization of the discrepancy between the probabilistic description of the dynamics of a quantum ensemble and a predefined desired probabilistic description is the key step in the proposed framework. With this objective, the derived solution will not only allow the transitioning of the ensemble from one state to another, but will generally allow steering an initial distribution of the ensemble to a final distribution. Numerical results are presented, demonstrating the effectiveness of the proposed probabilistic control framework.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"481 ","pages":"Article 170158"},"PeriodicalIF":3.0,"publicationDate":"2025-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144757233","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":"Geometric modeling of a line of alternating disclinations: Application to grain boundaries in graphene","authors":"A.M. de M. Carvalho ,&nbsp;C. Furtado","doi":"10.1016/j.aop.2025.170160","DOIUrl":"10.1016/j.aop.2025.170160","url":null,"abstract":"<div><div>We develop a conformal geometric model for grain boundaries in graphene based on a periodic line of alternating disclinations. Within the framework of <span><math><mrow><mo>(</mo><mn>2</mn><mo>+</mo><mn>1</mn><mo>)</mo></mrow></math></span>-dimensional gravity, we solve a reduced form of the Einstein equations to determine the conformal factor, from which the induced metric, scalar curvature, and holonomy are obtained analytically. Each pentagon–heptagon pair is modeled as a disclination dipole, forming a continuous distribution that captures the geometric signature of experimentally observed 5<span><math><mo>|</mo></math></span>7 grain boundaries. We show that the curvature is localized near the defect line and that the geometry becomes asymptotically flat, with trivial holonomy at large distances. This construction provides a tractable and physically consistent realization of the Katanaev–Volovich framework, connecting topological defect theory with atomistic features of graphene.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"481 ","pages":"Article 170160"},"PeriodicalIF":3.0,"publicationDate":"2025-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144724553","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":"Generalized relativistic second-order dissipative hydrodynamics: Coupling different rank tensors","authors":"Arus Harutyunyan ,&nbsp;Armen Sedrakian","doi":"10.1016/j.aop.2025.170159","DOIUrl":"10.1016/j.aop.2025.170159","url":null,"abstract":"<div><div>In this work, we extend the formalism of second-order relativistic dissipative hydrodynamics, developed previously using Zubarev’s non-equilibrium statistical operator formalism (Harutyunyan et al., 2022). By employing a second-order expansion of the statistical operator in terms of hydrodynamic gradients, we demonstrate that new second-order terms emerge due to the coupling of two-point quantum correlators between tensors of differing ranks, evaluated at distinct space–time points. Such terms arise because of the presence of the acceleration vector in the system allows Curie’s theorem, which governs symmetry constraints, to be extended for constructing invariants from tensors of different ranks evaluated at distinct space–time points. The new terms are identified in the context of a complete set of second-order equations governing the shear-stress tensor, bulk-viscous pressure, and charge-diffusion currents for a generic quantum system characterized by the energy–momentum tensor and multiple conserved charges. Additionally, we identify the transport coefficients associated with these new terms and derive the Kubo formulas expressing the second-order transport coefficients through two- and three-point correlation functions.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"481 ","pages":"Article 170159"},"PeriodicalIF":3.0,"publicationDate":"2025-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144748785","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":"Exploring complexity in a Schwarzschild radiating star","authors":"Megandhren Govender,&nbsp;Wesley Govender","doi":"10.1016/j.aop.2025.170156","DOIUrl":"10.1016/j.aop.2025.170156","url":null,"abstract":"<div><div>We study the notion of complexity as defined by Herrera (L. Herrera, Phys. Rev. D <strong>97</strong>, 044010 (2018) <span><span>[1]</span></span>) in a collapsing Schwarzschild-like star. Starting off with the static Schwarzschild interior solution cast in isotropic coordinates, we allow the mass function to be time-dependent. This gives rise to a dynamical radiating sphere with isotropic pressure and heat flux in the stellar interior. Since the star is radiating energy, the exterior spacetime is described by the Vaidya solution. The initial static solution described by the interior Schwarzschild solution is complexity-free. As hydrostatic equilibrium is lost and the configuration collapses, it enters a dynamical phase which is also complexity-free. We show that in order for the complexity to vanish, the density inhomogeneity is balanced by heat dissipation at each interior point of the stellar configuration.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"481 ","pages":"Article 170156"},"PeriodicalIF":3.0,"publicationDate":"2025-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144722735","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":"Wigner function for charged particles with spin 0 in non-commutative space","authors":"Dehong You,&nbsp;Yao Wang,&nbsp;Qi-Ming Fu,&nbsp;Junfeng He,&nbsp;Benzhuo Lou","doi":"10.1016/j.aop.2025.170154","DOIUrl":"10.1016/j.aop.2025.170154","url":null,"abstract":"<div><div>Wigner functions are quasi-probability distribution functions in phase space and play a crucial role in quantum optics, quantum information, and nuclear physics. In this paper,we first introduced the construction of the <span><math><msub><mrow><mo>⋆</mo></mrow><mrow><mi>θ</mi></mrow></msub></math></span>-product in non-commutative space and its relationship with the Wigner function. Then, we derived the eigenvalue equation of the Wigner function in non-commutative space using <span><math><msub><mrow><mo>⋆</mo></mrow><mrow><mi>θ</mi></mrow></msub></math></span>-product. Finally, we briefly discussed the role of <span><math><mi>θ</mi></math></span> in the observation of non-commutative effects in phase space within an electromagnetic field.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"481 ","pages":"Article 170154"},"PeriodicalIF":3.0,"publicationDate":"2025-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144715751","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":"Bulk viscous matter with decaying vacuum energy density: A model for late-time evolution of the Universe","authors":"Tanmay Nandi,&nbsp;Amitava Choudhuri","doi":"10.1016/j.aop.2025.170155","DOIUrl":"10.1016/j.aop.2025.170155","url":null,"abstract":"&lt;div&gt;&lt;div&gt;In this study, we combine viscous dark matter and running vacuum energy density in a single cosmological setting and investigate their cosmological implications. Specifically, we consider a well-studied form of running vacuum energy density model inspired by &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;f&lt;/mi&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;-gravity or, equivalently from the Brans–Dicke scalar-tensor theory that arises from a covariant action, i.e., &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;ρ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;Λ&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mi&gt;l&lt;/mi&gt;&lt;mfrac&gt;&lt;mrow&gt;&lt;mover&gt;&lt;mrow&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;̈&lt;/mo&gt;&lt;/mrow&gt;&lt;/mover&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;/mrow&gt;&lt;/mfrac&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mi&gt;λ&lt;/mi&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mfrac&gt;&lt;mrow&gt;&lt;mover&gt;&lt;mrow&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;̇&lt;/mo&gt;&lt;/mrow&gt;&lt;/mover&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;/mrow&gt;&lt;/mfrac&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mfrac&gt;&lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/mfrac&gt;&lt;mi&gt;η&lt;/mi&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;ρ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; and a recently proposed general parameterization for bulk viscosity &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;ζ&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;ζ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;ζ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mfrac&gt;&lt;mrow&gt;&lt;mover&gt;&lt;mrow&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;̇&lt;/mo&gt;&lt;/mrow&gt;&lt;/mover&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;/mrow&gt;&lt;/mfrac&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;ζ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mfrac&gt;&lt;mrow&gt;&lt;mover&gt;&lt;mrow&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;̈&lt;/mo&gt;&lt;/mrow&gt;&lt;/mover&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mover&gt;&lt;mrow&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;̇&lt;/mo&gt;&lt;/mrow&gt;&lt;/mover&gt;&lt;/mrow&gt;&lt;/mfrac&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, where &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;l&lt;/mi&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mi&gt;λ&lt;/mi&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mi&gt;η&lt;/mi&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;ζ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;ζ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; and &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;ζ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; are constants. In this setup, we derived analytical solutions for the Hubble parameter and the scale factor of the universe within the framework of Eckart’s theory of bulk viscosity. The viability of the proposed model equation is tested by constraining its free model parameters using the Hubble parameter &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;z&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; and type Ia supernovae (SNe Ia) observations at different redshifts, and the goodness-of-fit of the model to the data was also checked by a &lt;span&gt;&lt;math&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;χ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt; function minimization. Various significant cosmological parameters were estimated and analytically explained in the evolution dynamics of the universe, and a comparison of our proposed model with the &lt;span&gt;&lt;math&gt;&lt;mi&gt;Λ&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;CDM model was studied. The application of dynamical systems analysis reveals the physical aspects of the new phase space that emerge from the model and deri","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"481 ","pages":"Article 170155"},"PeriodicalIF":3.0,"publicationDate":"2025-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144722734","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":"Warp bubble geometries with anisotropic fluids: A piecewise analytical approach","authors":"N. Bolívar ,&nbsp;G. Abellán ,&nbsp;I. Vasilev","doi":"10.1016/j.aop.2025.170147","DOIUrl":"10.1016/j.aop.2025.170147","url":null,"abstract":"<div><div>We present a comprehensive analytical study of spherically symmetric warp bubble configurations in the framework of classical general relativity. We use a simplified ADM-type metric with a trivial lapse and a non-trivial radial shift function, which resembles a Painlevé–Gullstrand type metric. Employing this metric, our approach leads naturally to an anisotropic energy–momentum tensor characterized by an equation of state that emerges naturally from the equations. To reconcile the strict boundary conditions with the requirement of a localized matter distribution, we adopt a piecewise—defined model for the energy density. This construction allows us to confine possible violations of the dominant energy condition to finite and controlled shells, while ensuring that the weak and null energy conditions are globally satisfied. We illustrate our method with two representative examples: a one-shell exponential decay profile and a double-shell profile incorporating an additional power-law factor. Our results demonstrate that, by properly tuning the model parameters, it is possible to design warp bubble geometries that are not only mathematically consistent, but also physically more feasible, providing a promising stepping stone towards the development of realistic warp bubble models.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"481 ","pages":"Article 170147"},"PeriodicalIF":3.0,"publicationDate":"2025-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144724554","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}