Classical and Quantum Gravity最新文献_第3页

Exceptional points and cusp singularities in relativistic stellar oscillations with causal bulk relaxation 具有因果体松弛的相对论性恒星振荡中的异常点和尖点奇点

IF 3.5 3区物理与天体物理

Classical and Quantum Gravity Pub Date : 2026-10-05 DOI: 10.1088/1361-6382/aeb05c

Orlando Urbina-Gonzalez

{"title":"Exceptional points and cusp singularities in relativistic stellar oscillations with causal bulk relaxation","authors":"Orlando Urbina-Gonzalez","doi":"10.1088/1361-6382/aeb05c","DOIUrl":"https://doi.org/10.1088/1361-6382/aeb05c","url":null,"abstract":"Abstract Causal relativistic hydrodynamics promotes dissipative stresses to independent dynamical variables obeying first-order relaxation equations. When such relaxation channels are coupled to the second-order Einstein--fluid system, the stellar oscillation problem is generically elevated from a quadratic self-adjoint eigenvalue problem to a cubic non-Hermitian spectral problem in the complex frequency.&#xD;&#xD;We demonstrate that the resulting cubic operator possesses a structured non-Hermitian spectral geometry governed globally by its generalized discriminant. When the unperturbed stellar background is treated rigorously as an open system emitting gravitational radiation, the baseline quadratic operator acquires an intrinsic dissipation parameter $gamma$. We solve the complete spectral problem and prove that the strict $A_3$ (cusp) organizing center ceases to be fixed. First, we demonstrate that a consistent causal weak formulation naturally anchors the entire exceptional-point skeleton, including the cusp, firmly within the physically admissible parameter domain $(Lambda>0)$. Second, we show that open-system radiation damping continuously drives this cusp along an algebraic trajectory within this physical space. The physical curves of exceptional points (EP2) observed in the causal transport domain are shown to be the structural unfolding of this shifted open-system singularity.&#xD;&#xD;The effective spectral surface exhibits generic non-analytic behaviour, with square-root splitting near generic exceptional points, whereas the cubic-root scaling characterises the strict $A_3$ organizing center now natively rooted in the physical domain. These features arise from the structural interplay between second-order gravitational--fluid dynamics and first-order causal relaxation, characterising the robust topological skeleton of the system. The results establish the global geometric organisation of the non-Hermitian spectrum of relativistic stellar oscillations with causal bulk relaxation.&#xD;","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"36 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149089470","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}

引用次数: 0

Stochastic template banks for GW searches using low-discrepancy sequences 利用低差异序列进行GW搜索的随机模板库

IF 3.5 3区物理与天体物理

Classical and Quantum Gravity Pub Date : 2026-10-05 DOI: 10.1088/1361-6382/aeb05d

Tarun Kumar,Anand S. Sengupta

{"title":"Stochastic template banks for GW searches using low-discrepancy sequences","authors":"Tarun Kumar,Anand S. Sengupta","doi":"10.1088/1361-6382/aeb05d","DOIUrl":"https://doi.org/10.1088/1361-6382/aeb05d","url":null,"abstract":"Abstract Matched filtering remains the most sensitive method for detecting gravitational waves from compact binary coalescences. The efficiency of such searches depends on how well a discrete template bank covers the underlying parameter space. Conventional geometric, stochastic, and hybrid placement methods can lead to uneven coverage and redundant templates in higher dimensions. Hybrid methods are generally the most efficient among these, while stochastic methods are simpler to implement, particularly when the parameter-space metric is difficult to compute. In practice, both approaches rely on uniform random sampling, which often requires a large number of proposal points to achieve adequate coverage.&#xD;We find that stochastic template banks constructed using low-discrepancy sequences achieve comparable recovery fractions while requiring 27.5% fewer proposal points in two dimensions, about 12% fewer in three dimensions and 17% fewer in a four-dimensional eccentric equal-spin toy bank. The final template count is much less sensitive to the proposal sampling, consistent with the metric-volume constraints of the covering problem.&#xD;We introduce a slab-wise coarse prefilter to accelerate candidate rejection for strongly anisotropic metrics. Applied to the 4D toy bank, it gives a total bank-construction speed-up of about 1.28x.&#xD;The primary benefit of low-discrepancy sampling is therefore a reduction in the size of the initial proposal set, leading to lower memory usage and reduced bookkeeping during bank generation. These results show that low-discrepancy sampling provides a simple improvement to stochastic template-bank generation for current and future gravitational-wave searches.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"3 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149089471","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}

引用次数: 0

Electromagnetic Probes of the Supernova Engine 超新星引擎的电磁探针

IF 3.5 3区物理与天体物理

Classical and Quantum Gravity Pub Date : 2026-10-05 DOI: 10.1088/1361-6382/aeb086

Chris L Fryer

{"title":"Electromagnetic Probes of the Supernova Engine","authors":"Chris L Fryer","doi":"10.1088/1361-6382/aeb086","DOIUrl":"https://doi.org/10.1088/1361-6382/aeb086","url":null,"abstract":"Abstract Explosions from stellar collapse are important in nearly all aspects of astronomy: formation of compact remnants (including the potential seeds of supermassive black holes), the production of compact binaries the produce X-ray binaries and radio pulsars, the origin of many of the heavy elements (a critical aspect of galactic chemical evolution), and as standard candles to probe the early universe (including the nature of star formation). Because these explosions occur in extreme conditions, if we can understand them, they can be used to probe fundamental physics: matter at extreme densities (exceeding nuclear densities, quark formation), neutrino physics (including neutrino oscillations) and, in black-hole forming systems, the nature of relativity. Gravitational waves and neutrinos provide the most direct probe of stellar collapse, but these diagnostics require nearby events. Electromagnetic probes, from shock breakout to observations of supernova remnants, can be much more common and provide complementary diagnostics of the explosive engines behind stellar collapse. In this review, we review these electromagnetic diagnostics, the physics behind them and the theory and modeling work we require to take advantage of these probes.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"7 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149089474","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}

引用次数: 0

Topological Quantization of Complex Velocity in Stochastic Spacetimes 随机时空中复速度的拓扑量化

IF 3.5 3区物理与天体物理

Classical and Quantum Gravity Pub Date : 2026-10-05 DOI: 10.1088/1361-6382/aeb087

Jorge Meza-Domínguez,Tonatiuh Matos

{"title":"Topological Quantization of Complex Velocity in Stochastic Spacetimes","authors":"Jorge Meza-Domínguez,Tonatiuh Matos","doi":"10.1088/1361-6382/aeb087","DOIUrl":"https://doi.org/10.1088/1361-6382/aeb087","url":null,"abstract":"Abstract We establish a formal geometric framework for quantum fields on a stochastic gravitational background. Starting from a master partition function that averages over metric fluctuations, we define a matter amplitude $mathcal{K}[Phi; x]$ with explicit parametric dependence on spacetime coordinates, whose logarithmic derivative yields a complex velocity field $eta_{mu} = pi_{mu} - i u_{mu}$. This object is shown to be a section of the pullback bundle $E = pi_2^*(T^*M)$ over the product of configuration space $mathcal{C}$ and spacetime $M$, and defines a flat $mathbb{C}^times$ connection whose $U(1)$ part governs phase transport and whose $mathbb{R}^+$ part governs scale transport. The coupled dynamics collapse into the complex geodesic equation $mathcal{L}_{eta}eta = d(|eta|^2)$. On non-simply connected spacetimes, the total phase satisfies $frac{m}{hbar}oint_gamma eta_{mu} dx^{mu} = 2pi n + Deltaphi_{mathrm{top}}$, demonstrated analytically for a scalar field with twisted boundary conditions on a conical spacetime. We provide a self-contained bundle isomorphism mapping $eta_mu$ to the symmetric logarithmic derivative of quantum estimation theory, and derive the associated Berry curvature. A prospective estimate for the MAGIS-100 interferometer yields $gamma_B sim 3.97 times 10^{-9}$ rad for an astrophysical stochastic background (approximately five orders below projected sensitivity) and $gamma_B sim 3.97 times 10^{-53}$ rad for Planck-scale fluctuations. This framework geometrizes quantum mechanics without hidden variables: stochasticity imprints spacetime fluctuations on matter, preserving the wave function's probabilistic nature while maintaining consistency with the Born rule.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"480 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149089475","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}

引用次数: 0

Observational constraints on a non-minimally coupled scalar field in non-metricity gravitywith an extra degree of freedom 具有额外自由度的非度规重力非最小耦合标量场的观测约束

IF 3.5 3区物理与天体物理

Classical and Quantum Gravity Pub Date : 2026-10-02 DOI: 10.1088/1361-6382/aeaf9b

Saddam Hussain,Ghulam Murtaza,Avik De

{"title":"Observational constraints on a non-minimally coupled scalar field in non-metricity gravitywith an extra degree of freedom","authors":"Saddam Hussain,Ghulam Murtaza,Avik De","doi":"10.1088/1361-6382/aeaf9b","DOIUrl":"https://doi.org/10.1088/1361-6382/aeaf9b","url":null,"abstract":"Abstract We investigate a non-minimally coupled scalar field in non-metricity gravity, adopting a non-trivial connection class in spatially flat FLRW spacetimes. In contrast to the coincident-gauge choice, this connection class activates an additional dynamical degree of freedom (DoF) that modifies the background evolution. We study two representative models, defined by power-law and exponential coupling functions with the exponential potential for scalar field. Confronting both models with recent combined datasets - DESI BAO, two independent supernova compilations, and cosmic chronometers - we find that each reproduces an extended matter-dominated era&#xD;followed by a stable late-time de-Sitter attractor, with inferred parameters consistent with the standard $Lambda$CDM model. A complementary autonomous dynamical-system analysis identifies a sequence of critical points describing successive stiff-fluid, transient matter-dominated, and stable de-Sitter phases, ensuring a viable thermal history of the universe. The observational and dynamical results are mutually consistent and support the cosmological viability of the proposed models.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"166 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149089489","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}

引用次数: 0

Probing Lorentz-invariance-violation with quantum coherence of Unruh-DeWitt detector 用Unruh-DeWitt探测器的量子相干探测Lorentz-invariance-violation

IF 3.5 3区物理与天体物理

Classical and Quantum Gravity Pub Date : 2026-10-02 DOI: 10.1088/1361-6382/aeafa1

Yihao Wu,Xiaobao Liu,Zehua Tian

{"title":"Probing Lorentz-invariance-violation with quantum coherence of Unruh-DeWitt detector","authors":"Yihao Wu,Xiaobao Liu,Zehua Tian","doi":"10.1088/1361-6382/aeafa1","DOIUrl":"https://doi.org/10.1088/1361-6382/aeafa1","url":null,"abstract":"Abstract Testing Lorentz invariance violation (LIV) is notoriously difficult, as its characteristic energy scale, $M_star$, in modified dispersion relations typically lies beyond current experimental reach. To enable a low-energy probe, we investigate the quantum coherence of an inertial Unruh-DeWitt (UDW) detector interacting with a massless scalar field with a Lorentz-violating dispersion relation $omega_{|textbf{k}|}=|textbf{k}|f(|textbf{k}|/M_star)$. &#xD;Unlike the Lorentz-invariant case where quantum coherence is rapidity-independent, we find for the Lorentz-violating quantum field case&#xD;the dynamics of detector's quantum coherence exhibits a strong dependence on its rapidity---offering a potential low-energy signature of LIV.&#xD;Applying this to the polymer-quantized scalar field theory inspired by loop quantum gravity,&#xD;we show that the detector's quantum coherence exhibits a pronounced dependence on rapidity and undergoes a sharp transition near a critical rapidity $beta_c approx 1.3675$, a value within reach of existing facilities like the Relativistic Heavy Ion Collider. We also show how the detector's rapidity and its energy-level spacing enhance the response to the test of LIV. &#xD;Our results establish quantum coherence as a sensitive and practical probe of LIV, providing a complementary avenue for testing quantum gravity-induced modifications to field theory.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"1 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149089487","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}

引用次数: 0

Asymptotic expansion of the metric at null infinity 零无穷处度规的渐近展开式

IF 3.5 3区物理与天体物理

Classical and Quantum Gravity Pub Date : 2026-10-02 DOI: 10.1088/1361-6382/aeaf9e

Marc Mars,Gabriel Sánchez-Pérez

引用次数: 0

Path to robust analytical extensions of regular black holes 正则黑洞鲁棒解析扩展之路

IF 3.5 3区物理与天体物理

Classical and Quantum Gravity Pub Date : 2026-10-02 DOI: 10.1088/1361-6382/aeafa2

Hanwen Hu,Cheng-Jun Fang,Chen Lan,Xiaoning Wu,Zong-Kuan Guo

{"title":"Path to robust analytical extensions of regular black holes","authors":"Hanwen Hu,Cheng-Jun Fang,Chen Lan,Xiaoning Wu,Zong-Kuan Guo","doi":"10.1088/1361-6382/aeafa2","DOIUrl":"https://doi.org/10.1088/1361-6382/aeafa2","url":null,"abstract":"Abstract The construction of globally regular black hole spacetimes faces a subtle but fundamental challenge:&#xD;the mathematical consistency of the naive analytic extension across $r=0$.&#xD;We demonstrate that for spherically symmetric metrics lacking reflection symmetry (e.g., the Hayward model), the standard $S^2$ angular topology at the origin acts as &#xD;an obstruction to such naive through-going extension prescriptions. &#xD;This forces naive radial extensions to violate the Israel junction condition due to the divergence of extrinsic curvature.&#xD;To resolve this pathology, we propose a &#xD;local near-core regularization framework introducing a minimal angular correction $epsilon(r)$.&#xD;This correction is rigorously derived from the requirements of $C^infty$ geometric smoothness and dynamical stability under radial deformations.&#xD;Physically, the regularization transforms the degenerate central point into a non-vanishing minimal surface, identifying the geometry near $r=0$ as a black-bounce or wormhole throat supported by effective field theories. &#xD;This work provides a rigorous foundation for the physical meaning of ``regularity'' by establishing the necessary geometric conditions for analytical extensions of such spacetimes.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"15 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149089473","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}

引用次数: 0

Gravitational entropy in Petrov Type I spacetimes 彼得罗夫I型时空中的引力熵

IF 3.5 3区物理与天体物理

Classical and Quantum Gravity Pub Date : 2026-10-02 DOI: 10.1088/1361-6382/aeaf9d

MAHARSHI SARMA,Sebastián Nájera,Roberto A Sussman

引用次数: 0

Boltzmann Dynamics in K-essence Cosmology: Photon Propagation in an Emergent Spacetime k -本质宇宙学中的玻尔兹曼动力学：涌现时空中的光子传播

IF 3.5 3区物理与天体物理

Classical and Quantum Gravity Pub Date : 2026-10-02 DOI: 10.1088/1361-6382/aeafa0

Krishnendu Roy,Debashis Gangopadhyay,Chiranjeeb Singha,Goutam Manna

{"title":"Boltzmann Dynamics in K-essence Cosmology: Photon Propagation in an Emergent Spacetime","authors":"Krishnendu Roy,Debashis Gangopadhyay,Chiranjeeb Singha,Goutam Manna","doi":"10.1088/1361-6382/aeafa0","DOIUrl":"https://doi.org/10.1088/1361-6382/aeafa0","url":null,"abstract":"Abstract Recent cosmological tensions, notably the Hubble and $S_{8}$ tensions, motivate extensions of the conventional FLRW framework in which additional dynamical fields can alter the effective spacetime experienced by matter and radiation. In K-essence cosmology, the scalar field induces an emergent FLRW geometry disformally related to the gravitational metric, leading to a emph{tilted causal structure} in which the photon light cone differs from that of gravity. We develop a covariant Boltzmann formalism in a homogeneous K-essence background and derive the modified mass-shell condition, geodesic equations, and collision integrals for both massless and massive species. The photon distribution remains thermal in the emergent frame, while appearing geometrically rescaled in the gravitational frame. Microphysical Thomson/Compton scattering is unmodified; instead, the emergent geometry induces effective rest-frame energies and a geometrically rescaled scattering rate, conveniently encoded in a transport coefficient $sigma_T^{(mathrm{geom})}$. Focusing on the tightly coupled pre-recombination era, we obtain modified acoustic dynamics and, for a purely kinetic DBI-type model, find an effective interaction rate scaling $n_{e}sigma_T^{(mathrm{geom})}apropto a^{-8}$ and a diffusion scale scaling $k_{D}^{-2}propto a^{29/2}$, enhancing the sensitivity of small-scale anisotropies to the evolving geometry. Our results provide a self-consistent kinetic description of particle transport in the emergent K-essence spacetime, and they lay the groundwork for a full numerical Einstein-Boltzmann implementation to compute post-recombination free streaming and the CMB angular power spectrum. A detailed numerical analysis will be pursued in future work.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"17 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149089477","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}

引用次数: 0