Pub Date : 2026-02-01Epub Date: 2025-12-16DOI: 10.1016/j.aop.2025.170326
Jesse Huhtala, Iiro Vilja
In quantum field theory, sharp momentum states have to be normalized to be in Fock space. We investigate two different normalization schemes: box normalization and wave packets. These methods are equivalent in flat spacetimes, but turn out to produce different results in curved spacetimes, specifically in those that break translation invariance. This means that scattering processes have to be defined in relation to the normalization scheme used, rather than being independent of it as is the case in flat spacetime. We prove this and provide an illustrative example.
{"title":"Normalizing Fock space states in static spacetimes","authors":"Jesse Huhtala, Iiro Vilja","doi":"10.1016/j.aop.2025.170326","DOIUrl":"10.1016/j.aop.2025.170326","url":null,"abstract":"<div><div>In quantum field theory, sharp momentum states have to be normalized to be in Fock space. We investigate two different normalization schemes: box normalization and wave packets. These methods are equivalent in flat spacetimes, but turn out to produce different results in curved spacetimes, specifically in those that break translation invariance. This means that scattering processes have to be defined in relation to the normalization scheme used, rather than being independent of it as is the case in flat spacetime. We prove this and provide an illustrative example.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"485 ","pages":"Article 170326"},"PeriodicalIF":3.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145797571","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}
Pub Date : 2026-02-01Epub Date: 2025-12-16DOI: 10.1016/j.aop.2025.170323
A.A. Araújo Filho , Iarley P. Lobo
A recent study (Touati and Zaim, 2023) examined the thermodynamic behavior of an axially symmetric black hole within a non–commutative framework that mimics the effect of an angular momentum. However, the analysis presents notable computational inconsistencies. In that analysis, the event horizon was miscalculated, and this error propagated through and compromised all subsequent results. In addition, an incorrect definition of surface gravity was used — the spherically symmetric case was invoked for an axially symmetric spacetime — rendering the thermodynamic results invalid. In other words, all the results presented in the paper require a thorough reexamination.
{"title":"Comment on “Thermodynamic properties of Schwarzschild black hole in non-commutative gauge theory of gravity”","authors":"A.A. Araújo Filho , Iarley P. Lobo","doi":"10.1016/j.aop.2025.170323","DOIUrl":"10.1016/j.aop.2025.170323","url":null,"abstract":"<div><div>A recent study (Touati and Zaim, 2023) examined the thermodynamic behavior of an axially symmetric black hole within a non–commutative framework that mimics the effect of an angular momentum. However, the analysis presents notable computational inconsistencies. In that analysis, the event horizon was miscalculated, and this error propagated through and compromised all subsequent results. In addition, an incorrect definition of surface gravity was used — the spherically symmetric case was invoked for an axially symmetric spacetime — rendering the thermodynamic results invalid. In other words, all the results presented in the paper require a thorough reexamination.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"485 ","pages":"Article 170323"},"PeriodicalIF":3.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145797573","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}
Pub Date : 2026-02-01Epub Date: 2025-12-03DOI: 10.1016/j.aop.2025.170318
Xi Ming , Qing-yu Cai
This work investigates the fundamental connection between quantum mechanics and thermodynamics through the concept of the arrow of time. While the second law of thermodynamics identifies the arrow of time with the monotonic increase of entropy in isolated systems, closed quantum systems evolve unitarily and conserve von Neumann entropy, making the origin of irreversibility less apparent. Here we establish a no-go theorem proving that correlations in unknown states of closed quantum systems cannot be universally removed by any physical operation. This result demonstrates that correlation generation is inherently irreversible, providing a microscopic and universal basis for the arrow of time. In thermodynamic settings, this irreversibility ensures that heat flows spontaneously from hotter to colder subsystems, reproducing the Clausius formulation of the second law. More generally, the irreversible growth of correlations explains entropy increase, the approach to equilibrium, and decoherence as observable manifestations of the same principle. Our findings ground a quantum-mechanical foundation for the second law of thermodynamics and demonstrate the universality of the arrow of time.
{"title":"Bridging quantum mechanics and thermodynamics: Irreversible correlations as the arrow of time","authors":"Xi Ming , Qing-yu Cai","doi":"10.1016/j.aop.2025.170318","DOIUrl":"10.1016/j.aop.2025.170318","url":null,"abstract":"<div><div>This work investigates the fundamental connection between quantum mechanics and thermodynamics through the concept of the arrow of time. While the second law of thermodynamics identifies the arrow of time with the monotonic increase of entropy in isolated systems, closed quantum systems evolve unitarily and conserve von Neumann entropy, making the origin of irreversibility less apparent. Here we establish a no-go theorem proving that correlations in unknown states of closed quantum systems cannot be universally removed by any physical operation. This result demonstrates that correlation generation is inherently irreversible, providing a microscopic and universal basis for the arrow of time. In thermodynamic settings, this irreversibility ensures that heat flows spontaneously from hotter to colder subsystems, reproducing the Clausius formulation of the second law. More generally, the irreversible growth of correlations explains entropy increase, the approach to equilibrium, and decoherence as observable manifestations of the same principle. Our findings ground a quantum-mechanical foundation for the second law of thermodynamics and demonstrate the universality of the arrow of time.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"485 ","pages":"Article 170318"},"PeriodicalIF":3.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145747818","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}
We investigate the current–voltage characteristics of an extended Su–Schrieffer–Heeger (SSH) chain under irradiation by arbitrarily polarized light, demonstrating its potential as a light-controlled rectifier. Irradiation of light induces anisotropy in the system, enabling directional current flow and active control of rectification behavior. Our analysis demonstrates that, under optimized light parameters, the rectification efficiency can exceed 90%. Moreover, the direction of rectification – whether positive or negative – can be precisely controlled by varying the polarization of the light, highlighting the potential for external optical control of electronic behavior. The effect of light irradiation is incorporated using the Floquet–Bloch ansatz combined with the minimal coupling scheme, while charge transport is computed through the nonequilibrium Green’s function formalism within the Landauer–Büttiker framework.
我们研究了任意偏振光照射下延伸的Su-Schrieffer-Heeger （SSH）链的电流-电压特性，证明了它作为光控整流器的潜力。光的照射引起系统的各向异性，使定向电流流动和整流行为的主动控制成为可能。我们的分析表明，在优化的光参数下，整流效率可以超过90%。此外，整流方向——无论是正的还是负的——可以通过改变光的偏振来精确控制，突出了外部光学控制电子行为的潜力。光照射的影响采用Floquet-Bloch ansatz结合最小耦合方案，而电荷输运则通过landauer - b ttiker框架内的非平衡格林函数形式计算。
{"title":"Photo-induced directional transport in extended SSH chains","authors":"Usham Harish Kumar Singha , Kallol Mondal , Sudin Ganguly , Santanu K. Maiti","doi":"10.1016/j.aop.2025.170317","DOIUrl":"10.1016/j.aop.2025.170317","url":null,"abstract":"<div><div>We investigate the current–voltage characteristics of an extended Su–Schrieffer–Heeger (SSH) chain under irradiation by arbitrarily polarized light, demonstrating its potential as a light-controlled rectifier. Irradiation of light induces anisotropy in the system, enabling directional current flow and active control of rectification behavior. Our analysis demonstrates that, under optimized light parameters, the rectification efficiency can exceed 90%. Moreover, the direction of rectification – whether positive or negative – can be precisely controlled by varying the polarization of the light, highlighting the potential for external optical control of electronic behavior. The effect of light irradiation is incorporated using the Floquet–Bloch ansatz combined with the minimal coupling scheme, while charge transport is computed through the nonequilibrium Green’s function formalism within the Landauer–Büttiker framework.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"485 ","pages":"Article 170317"},"PeriodicalIF":3.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145691989","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}
Pub Date : 2026-02-01Epub Date: 2025-12-22DOI: 10.1016/j.aop.2025.170331
Nuno Barros e Sá
We present proofs of two results: (a) The currents arising from Noether’s first theorem in a physical theory with local invariance can always be decomposed into two terms, one of them vanishing on-shell, and the other having an off-shell vanishing divergence, or that they are improper, using the original terminology of Noether; (b) When there is a current which is covariantly conserved, it differs from the canonical current by an improper current. Both proofs are performed in the most general case, that is, for arbitrary maximal order of the derivatives of the dynamical fields of the theory in the Lagrangian, and for arbitrary maximal order of the derivatives of the parameters of the symmetry transformations present in the infinitesimal transformations of the fields and spacetime coordinates. Both proofs are made using only . These are alternative proofs of known results which, besides making use of elementary calculus only, rendering them accessible to a large number of physicists, present the novelty of providing, in both cases, explicit formulae for the decomposition of the improper currents into their two terms (the one vanishing on-shell and the one whose divergence vanishes off-shell).
{"title":"Improper currents in theories with local invariance","authors":"Nuno Barros e Sá","doi":"10.1016/j.aop.2025.170331","DOIUrl":"10.1016/j.aop.2025.170331","url":null,"abstract":"<div><div>We present proofs of two results: (a) The currents arising from Noether’s first theorem in a physical theory with local invariance can always be decomposed into two terms, one of them vanishing on-shell, and the other having an off-shell vanishing divergence, or that they are improper, using the original terminology of Noether; (b) When there is a current which is covariantly conserved, it differs from the canonical current by an improper current. Both proofs are performed in the most general case, that is, for arbitrary maximal order of the derivatives of the dynamical fields of the theory in the Lagrangian, and for arbitrary maximal order of the derivatives of the parameters of the symmetry transformations present in the infinitesimal transformations of the fields and spacetime coordinates. Both proofs are made using only . These are alternative proofs of known results which, besides making use of elementary calculus only, rendering them accessible to a large number of physicists, present the novelty of providing, in both cases, explicit formulae for the decomposition of the improper currents into their two terms (the one vanishing on-shell and the one whose divergence vanishes off-shell).</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"485 ","pages":"Article 170331"},"PeriodicalIF":3.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145836665","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}
In this study, we investigate the stability of the Einstein Static Universe within gravity under homogeneous anisotropic perturbations in both scale factors and matter. The perturbed field equations are derived using a linear equation of state, and two specific models are analyzed. The Arctan model, , yields bounded curvature and smooth transitions across regimes, while the Logarithmic model, , incorporates quantum-motivated corrections. For each model, stability conditions are obtained and stability regions are mapped in parameter space. Our analysis shows that both models admit stable Einstein Static Universe solutions within certain parameter ranges, in contrast with the instability predicted by General Relativity.
{"title":"Cosmic evolution and stability of the Einstein Static Universe in modified gravity models","authors":"Sana Saleem , Jawahir Waqqas , Tooba Tariq , S.A. Mardan","doi":"10.1016/j.aop.2025.170321","DOIUrl":"10.1016/j.aop.2025.170321","url":null,"abstract":"<div><div>In this study, we investigate the stability of the Einstein Static Universe within <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>R</mi><mo>)</mo></mrow></mrow></math></span> gravity under homogeneous anisotropic perturbations in both scale factors and matter. The perturbed field equations are derived using a linear equation of state, and two specific models are analyzed. The Arctan model, <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>R</mi><mo>)</mo></mrow><mo>=</mo><mi>λ</mi><mo>arctan</mo><mrow><mo>(</mo><mi>R</mi><mo>)</mo></mrow></mrow></math></span>, yields bounded curvature and smooth transitions across regimes, while the Logarithmic model, <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>R</mi><mo>)</mo></mrow><mo>=</mo><mi>β</mi><mo>ln</mo><mrow><mo>(</mo><mi>R</mi><mo>)</mo></mrow><mo>+</mo><mi>R</mi></mrow></math></span>, incorporates quantum-motivated corrections. For each model, stability conditions are obtained and stability regions are mapped in parameter space. Our analysis shows that both models admit stable Einstein Static Universe solutions within certain parameter ranges, in contrast with the instability predicted by General Relativity.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"485 ","pages":"Article 170321"},"PeriodicalIF":3.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145797572","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}
Pub Date : 2026-02-01Epub Date: 2025-12-17DOI: 10.1016/j.aop.2025.170319
Rounak Manna , Ujjal Debnath , Anirudh Pradhan
The main objective of this study is to inspect the dynamical characteristics of thin-shell wormholes originating from the Euler–Heisenberg anti-de Sitter (EHAdS) black hole. Within the framework of the Darmois–Israel formalism, this kind of geometric framework is produced by considering the cut-and-paste procedure to avoid the emergence of a singularity and to determine the location of the event horizon. Furthermore, we observe that the elements of stress energy inside the wormhole’s shell defy the weak- and null-energy requirements yet satisfy the criteria of strong energy. Next, we briefly review the gravitational properties (attractive or repulsive) of our wormhole solution. Next, we determine how much exotic substance is required overall to keep the throat of the wormhole open. Afterwards, we use the linearized radial perturbation to analyze the stability of the constructed wormhole structure through the assumption of three distinct variable equations of state (EoS), such as barotropic, phantom-like, and Chaplygin variable EoS. Our research reveals the presence of stable and unstable areas, which depend on how well certain parameters are chosen inside the metric spacetime and EoS. This analysis is further extended in a non-perturbative framework under different EoSs to explore stability beyond small perturbations. Finally, possible observational signatures are considered through the study of light deflection by thin-shell wormholes in EHAdS spacetime. Overall, the findings are highly intriguing and practically feasible in terms of the thin-shell wormhole stability problem.
{"title":"Stability of thin-shell wormholes constructed from Euler–Heisenberg AdS black holes","authors":"Rounak Manna , Ujjal Debnath , Anirudh Pradhan","doi":"10.1016/j.aop.2025.170319","DOIUrl":"10.1016/j.aop.2025.170319","url":null,"abstract":"<div><div>The main objective of this study is to inspect the dynamical characteristics of thin-shell wormholes originating from the Euler–Heisenberg anti-de Sitter (EHAdS) black hole. Within the framework of the Darmois–Israel formalism, this kind of geometric framework is produced by considering the cut-and-paste procedure to avoid the emergence of a singularity and to determine the location of the event horizon. Furthermore, we observe that the elements of stress energy inside the wormhole’s shell defy the weak- and null-energy requirements yet satisfy the criteria of strong energy. Next, we briefly review the gravitational properties (attractive or repulsive) of our wormhole solution. Next, we determine how much exotic substance is required overall to keep the throat of the wormhole open. Afterwards, we use the linearized radial perturbation to analyze the stability of the constructed wormhole structure through the assumption of three distinct variable equations of state (EoS), such as barotropic, phantom-like, and Chaplygin variable EoS. Our research reveals the presence of stable and unstable areas, which depend on how well certain parameters are chosen inside the metric spacetime and EoS. This analysis is further extended in a non-perturbative framework under different EoSs to explore stability beyond small perturbations. Finally, possible observational signatures are considered through the study of light deflection by thin-shell wormholes in EHAdS spacetime. Overall, the findings are highly intriguing and practically feasible in terms of the thin-shell wormhole stability problem.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"485 ","pages":"Article 170319"},"PeriodicalIF":3.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145797574","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}
Pub Date : 2026-02-01Epub Date: 2025-12-10DOI: 10.1016/j.aop.2025.170320
Adnan Malik , Aimen Rauf , P.K. Sahoo , Wenbin Lin , Fatemah Mofarreh
This study investigates cosmological dynamics in modified gravity, where spacetime geometry is governed by the non-metricity scalar . Using Friedmann–Robertson–Walker spacetime, we derive exact cosmological solutions for six distinct epochs: dark energy-dominated, dust-dominated, sub-relativistic, radiation-dominated, ultra-relativistic, and stiff fluid phases. Employing a power-law approach, we analyze the universe’s evolutionary dynamics, identifying parameter ranges that satisfy energy conditions for viable bouncing cosmologies. We further examine three specific bouncing scenarios — symmetric bounce, superbounce, and oscillatory cosmology — within the framework, assessing their mathematical consistency and physical implications. Our results demonstrate how gravity can simultaneously address singularity avoidance, describe multi-phase cosmic evolution, and provide alternatives to standard cosmological paradigms while maintaining fundamental energy conditions. The findings highlight the theory’s potential to unify diverse cosmological phenomena through geometric modifications of gravity.
{"title":"Dark energy cosmological solutions in f(Q) modified gravity","authors":"Adnan Malik , Aimen Rauf , P.K. Sahoo , Wenbin Lin , Fatemah Mofarreh","doi":"10.1016/j.aop.2025.170320","DOIUrl":"10.1016/j.aop.2025.170320","url":null,"abstract":"<div><div>This study investigates cosmological dynamics in modified <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>Q</mi><mo>)</mo></mrow></mrow></math></span> gravity, where spacetime geometry is governed by the non-metricity scalar <span><math><mi>Q</mi></math></span>. Using Friedmann–Robertson–Walker spacetime, we derive exact cosmological solutions for six distinct epochs: dark energy-dominated, dust-dominated, sub-relativistic, radiation-dominated, ultra-relativistic, and stiff fluid phases. Employing a power-law approach, we analyze the universe’s evolutionary dynamics, identifying parameter ranges that satisfy energy conditions for viable bouncing cosmologies. We further examine three specific bouncing scenarios — symmetric bounce, superbounce, and oscillatory cosmology — within the <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>Q</mi><mo>)</mo></mrow></mrow></math></span> framework, assessing their mathematical consistency and physical implications. Our results demonstrate how <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>Q</mi><mo>)</mo></mrow></mrow></math></span> gravity can simultaneously address singularity avoidance, describe multi-phase cosmic evolution, and provide alternatives to standard cosmological paradigms while maintaining fundamental energy conditions. The findings highlight the theory’s potential to unify diverse cosmological phenomena through geometric modifications of gravity.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"485 ","pages":"Article 170320"},"PeriodicalIF":3.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145748920","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}
Pub Date : 2026-02-01Epub Date: 2025-12-18DOI: 10.1016/j.aop.2025.170328
Anirudh Pradhan , K. Ghaderi , M. Zeyauddin
We study the optical properties of a new regular Gaussian black hole embedded in a cold isotropic non magnetized refractive plasma. The spacetime is sourced by a Gaussian matter distribution with smearing scale . Photon motion is analyzed for three plasma prescriptions: a uniform medium with constant plasma frequency, a singular isothermal sphere (SIS), and a radially decreasing model. Numerically we find that increasing enlarges both the photon sphere and the shadow, whereas stronger plasma reduces them through dispersion. In the weak field regime the bending angle increases with , while the magnification depends on the plasma profile: it is reduced as plasma strength grows and, for steep inhomogeneous profiles such as SIS, larger further lowers the net magnification due to core smoothing and refractive gradients. Mapping the shadow size to M87* and Sgr A* shows consistency with current Event Horizon Telescope (EHT) constraints for small and moderate plasma strength. These trends provide observational tests of quadratic spacetimes in dispersive media and motivate multi frequency analyses to disentangle geometric and environmental effects.
{"title":"A new regular R2 Gaussian black hole in refractive plasma: Observable signatures and EHT constraints","authors":"Anirudh Pradhan , K. Ghaderi , M. Zeyauddin","doi":"10.1016/j.aop.2025.170328","DOIUrl":"10.1016/j.aop.2025.170328","url":null,"abstract":"<div><div>We study the optical properties of a new regular <span><math><msup><mrow><mi>R</mi></mrow><mrow><mn>2</mn></mrow></msup></math></span> Gaussian black hole embedded in a cold isotropic non magnetized refractive plasma. The spacetime is sourced by a Gaussian matter distribution with smearing scale <span><math><mi>α</mi></math></span>. Photon motion is analyzed for three plasma prescriptions: a uniform medium with constant plasma frequency, a singular isothermal sphere (SIS), and a radially decreasing model. Numerically we find that increasing <span><math><mi>α</mi></math></span> enlarges both the photon sphere and the shadow, whereas stronger plasma reduces them through dispersion. In the weak field regime the bending angle increases with <span><math><mi>α</mi></math></span>, while the magnification depends on the plasma profile: it is reduced as plasma strength grows and, for steep inhomogeneous profiles such as SIS, larger <span><math><mi>α</mi></math></span> further lowers the net magnification due to core smoothing and refractive gradients. Mapping the shadow size to M87* and Sgr A* shows consistency with current Event Horizon Telescope (EHT) constraints for small <span><math><mi>α</mi></math></span> and moderate plasma strength. These trends provide observational tests of quadratic <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>R</mi><mo>)</mo></mrow></mrow></math></span> spacetimes in dispersive media and motivate multi frequency analyses to disentangle geometric and environmental effects.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"485 ","pages":"Article 170328"},"PeriodicalIF":3.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145797575","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}
Pub Date : 2026-02-01Epub Date: 2025-12-05DOI: 10.1016/j.aop.2025.170314
Samuel Fedida
We investigate a generalisation to Lüders’ rule à la Aharonov–Albert in those globally hyperbolic spacetimes which allow unitarily equivalent Hilbert spaces to be defined along Cauchy hypersurfaces, thus relying on the existence of an interaction picture à la Tomonaga–Schwinger. We show that under this rule and under the additional assumptions of the integrability and unitarity of the Tomonaga–Schwinger dynamics and the foliation-independence of rays on acausal Cauchy hypersurfaces, selective quantum measurements satisfy a state-independent anyonic commutation relation over spacelike-separated precompact regions. We highlight that this propagates to positive operator-valued measures, where the commutation is necessarily bosonic. In the instantaneous-measurement idealisation, this implies quantum no-signalling for non-selective measurements. We then examine Sorkin’s impossible measurements and show that immediate contradictions can be averted as long as collapse-inducing measurements are irreversible. These results reaffirm the consistency of the Tomonaga–Schwinger picture of relativistic quantum theory, for which unitarity, integrability and foliation-independence of the states exclude superluminal signalling despite the “instantaneity” of a side-cone measurement collapse rule. We finish by discussing the possibility of extending such results beyond the interaction picture.
{"title":"Einstein causality of quantum measurements in the Tomonaga–Schwinger picture","authors":"Samuel Fedida","doi":"10.1016/j.aop.2025.170314","DOIUrl":"10.1016/j.aop.2025.170314","url":null,"abstract":"<div><div>We investigate a generalisation to Lüders’ rule à la Aharonov–Albert in those globally hyperbolic spacetimes which allow unitarily equivalent Hilbert spaces to be defined along Cauchy hypersurfaces, thus relying on the existence of an interaction picture à la Tomonaga–Schwinger. We show that under this rule and under the additional assumptions of the integrability and unitarity of the Tomonaga–Schwinger dynamics and the foliation-independence of rays on acausal Cauchy hypersurfaces, selective quantum measurements satisfy a state-independent anyonic commutation relation over spacelike-separated precompact regions. We highlight that this propagates to positive operator-valued measures, where the commutation is necessarily bosonic. In the instantaneous-measurement idealisation, this implies quantum no-signalling for non-selective measurements. We then examine Sorkin’s impossible measurements and show that immediate contradictions can be averted as long as collapse-inducing measurements are irreversible. These results reaffirm the consistency of the Tomonaga–Schwinger picture of relativistic quantum theory, for which unitarity, integrability and foliation-independence of the states exclude superluminal signalling despite the “instantaneity” of a side-cone measurement collapse rule. We finish by discussing the possibility of extending such results beyond the interaction picture.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"485 ","pages":"Article 170314"},"PeriodicalIF":3.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145748921","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}
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