Pub Date : 2026-01-01Epub Date: 2025-11-15DOI: 10.1016/j.aop.2025.170290
Sebastián Mendizabal
We study propagators in bosonic field theories at finite temperature and chemical potential using the Schwinger–Keldysh real-time formalism. The system is considered in contact with a thermal reservoir, allowing for a consistent treatment of both equilibrium and non-equilibrium situations. The chemical potential, associated with conserved charges, modifies the structure of the propagators and introduces features that require detailed analysis.
We focus on how a finite chemical potential affects the analytic structure of the bosonic propagators, including changes in the position of poles and the structure of branch cuts. In our setup, the chemical potential enters the theory as a constant background field, which alters both the dynamics and the boundary conditions. This work provides a basis for understanding the behavior of bosonic fields in thermal and dense environments.
{"title":"Non-equilibrium scalar fields at finite temperature and density","authors":"Sebastián Mendizabal","doi":"10.1016/j.aop.2025.170290","DOIUrl":"10.1016/j.aop.2025.170290","url":null,"abstract":"<div><div>We study propagators in bosonic field theories at finite temperature and chemical potential using the Schwinger–Keldysh real-time formalism. The system is considered in contact with a thermal reservoir, allowing for a consistent treatment of both equilibrium and non-equilibrium situations. The chemical potential, associated with conserved charges, modifies the structure of the propagators and introduces features that require detailed analysis.</div><div>We focus on how a finite chemical potential affects the analytic structure of the bosonic propagators, including changes in the position of poles and the structure of branch cuts. In our setup, the chemical potential enters the theory as a constant background field, which alters both the dynamics and the boundary conditions. This work provides a basis for understanding the behavior of bosonic fields in thermal and dense environments.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"484 ","pages":"Article 170290"},"PeriodicalIF":3.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145577896","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 : 2026-01-01Epub Date: 2025-11-07DOI: 10.1016/j.aop.2025.170278
Parviz Goodarzi
We investigate slow roll inflation and the creation of primordial density fluctuations in the framework of gravity. Our focus is on constraining the evolution of both the background and perturbations in this theory, specifically using the form , where is an arbitrary function of the trace of the stress–energy tensor . We derive the Mukhanov–Sasaki equations for scalar and tensor perturbations and, by solving them in the slow-roll regime, compute the power spectra and spectral indices for both scalar and tensor modes within the general functional form of . In particular, we examine power law functional forms of to establish the observational constraints associated with quadratic potential. By imposing constraints on the model’s parameters, we obtain results that align closely with the Planck 2018 data and BAO data for the tensor-to-scalar ratio. Notably, a model incorporating along with a quadratic potential yields best-fit values consistent with the spectral index and tensor-to-scalar ratio suggested by the Planck and BICEP2 observations. By choosing appropriate values of the parameter , the results of this model closely resemble those of the Starobinsky model of inflation.
{"title":"Primordial fluctuations from slow-roll inflation in f(Q,T) gravity","authors":"Parviz Goodarzi","doi":"10.1016/j.aop.2025.170278","DOIUrl":"10.1016/j.aop.2025.170278","url":null,"abstract":"<div><div>We investigate slow roll inflation and the creation of primordial density fluctuations in the framework of <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>Q</mi><mo>,</mo><mi>T</mi><mo>)</mo></mrow></mrow></math></span> gravity. Our focus is on constraining the evolution of both the background and perturbations in this theory, specifically using the form <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>Q</mi><mo>,</mo><mi>T</mi><mo>)</mo></mrow><mo>=</mo><mi>α</mi><mi>Q</mi><mo>+</mo><mi>g</mi><mrow><mo>(</mo><mi>T</mi><mo>)</mo></mrow></mrow></math></span>, where <span><math><mrow><mi>g</mi><mrow><mo>(</mo><mi>T</mi><mo>)</mo></mrow></mrow></math></span> is an arbitrary function of the trace of the stress–energy tensor <span><math><mi>T</mi></math></span>. We derive the Mukhanov–Sasaki equations for scalar and tensor perturbations and, by solving them in the slow-roll regime, compute the power spectra and spectral indices for both scalar and tensor modes within the general functional form of <span><math><mrow><mi>g</mi><mrow><mo>(</mo><mi>T</mi><mo>)</mo></mrow></mrow></math></span>. In particular, we examine power law functional forms of <span><math><mrow><mi>g</mi><mrow><mo>(</mo><mi>T</mi><mo>)</mo></mrow></mrow></math></span> to establish the observational constraints associated with quadratic potential. By imposing constraints on the model’s parameters, we obtain results that align closely with the Planck 2018 data and BAO data for the tensor-to-scalar ratio. Notably, a model incorporating <span><math><mrow><mi>g</mi><mrow><mo>(</mo><mi>T</mi><mo>)</mo></mrow><mo>=</mo><mi>β</mi><msup><mrow><mi>T</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></math></span> along with a quadratic potential yields best-fit values consistent with the spectral index and tensor-to-scalar ratio suggested by the Planck and BICEP2 observations. By choosing appropriate values of the parameter <span><math><mi>β</mi></math></span>, the results of this model closely resemble those of the Starobinsky model of inflation.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"484 ","pages":"Article 170278"},"PeriodicalIF":3.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145527769","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 : 2026-01-01Epub Date: 2025-11-10DOI: 10.1016/j.aop.2025.170286
Altin Shala , Volker Perlick
We investigate the feasibility of probing Bopp–Landé–Thomas–Podolsky generalized electrodynamics with traveling and standing wave experiments. We consider wave propagation in vacuum and in a cold and non-magnetized plasma. Dispersion relations are found for all possible transverse and longitudinal modes. Longitudinal traveling waves are found which exhibit negative group velocities.
我们研究了用行波和驻波实验探测bopp - land - thomas - podolsky广义电动力学的可行性。我们考虑了波在真空和冷的非磁化等离子体中的传播。找到了所有可能的横向和纵向模的色散关系。发现纵向行波呈现负群速度。
{"title":"Waves in Bopp–Landé–Thomas–Podolsky generalized electrodynamics","authors":"Altin Shala , Volker Perlick","doi":"10.1016/j.aop.2025.170286","DOIUrl":"10.1016/j.aop.2025.170286","url":null,"abstract":"<div><div>We investigate the feasibility of probing Bopp–Landé–Thomas–Podolsky generalized electrodynamics with traveling and standing wave experiments. We consider wave propagation in vacuum and in a cold and non-magnetized plasma. Dispersion relations are found for all possible transverse and longitudinal modes. Longitudinal traveling waves are found which exhibit negative group velocities.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"484 ","pages":"Article 170286"},"PeriodicalIF":3.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145479110","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 : 2026-01-01Epub Date: 2025-11-20DOI: 10.1016/j.aop.2025.170293
Marco Galoppo , Giorgio Torrieri
Motivated by known facts about effective field theory and non-Abelian gauge theory, we argue that the post-Newtonian approximation might fail even in the limit of weak fields and small velocities for wide-extended rotating bodies, where angular momentum spans significant spacetime curvature. We construct a novel dimensionless quantity that samples this breakdown, and we evaluate it by means of existing analytical solutions of rotating extended bodies and observational data. We give estimates for galaxies and binary systems, as well as our home in the Cosmos, Laniakea. We thus propose that a novel effective field theory of general relativity might be needed to account for the onset of nonlocal angular momentum effects.
{"title":"The need for a nonlocal expansion in general relativity","authors":"Marco Galoppo , Giorgio Torrieri","doi":"10.1016/j.aop.2025.170293","DOIUrl":"10.1016/j.aop.2025.170293","url":null,"abstract":"<div><div>Motivated by known facts about effective field theory and non-Abelian gauge theory, we argue that the post-Newtonian approximation might fail even in the limit of weak fields and small velocities for wide-extended rotating bodies, where angular momentum spans significant spacetime curvature. We construct a novel dimensionless quantity that samples this breakdown, and we evaluate it by means of existing analytical solutions of rotating extended bodies and observational data. We give estimates for galaxies and binary systems, as well as our home in the Cosmos, Laniakea. We thus propose that a novel effective field theory of general relativity might be needed to account for the onset of nonlocal angular momentum effects.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"484 ","pages":"Article 170293"},"PeriodicalIF":3.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145577895","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 : 2025-12-01Epub Date: 2025-10-08DOI: 10.1016/j.aop.2025.170246
José Weberszpil
We present a comprehensive functional deformation framework for modified gravity, based on an operator that continuously interpolates between a field and its spatial derivative. This approach naturally generates a deformed velocity profile for circular orbits, capable of accurately reproducing galactic rotation curves without invoking dark matter. A variational formulation is constructed, revealing the deformation as a modification of inertia rather than gravity itself. We introduce both standard and hybrid q-deformed profiles that successfully model a range of spiral and dwarf galaxies. The model demonstrates empirical viability for spiral galaxies and theoretical consistency within a geometric-thermodynamic context. The framework provides clear physical interpretation through information theory while maintaining mathematical rigor through variational principles.
{"title":"Functional q-deformation of orbital velocity in emergent gravitation: Extended framework and galactic applications","authors":"José Weberszpil","doi":"10.1016/j.aop.2025.170246","DOIUrl":"10.1016/j.aop.2025.170246","url":null,"abstract":"<div><div>We present a comprehensive functional deformation framework for modified gravity, based on an operator that continuously interpolates between a field and its spatial derivative. This approach naturally generates a deformed velocity profile for circular orbits, capable of accurately reproducing galactic rotation curves without invoking dark matter. A variational formulation is constructed, revealing the deformation as a modification of inertia rather than gravity itself. We introduce both standard and hybrid q-deformed profiles that successfully model a range of spiral and dwarf galaxies. The model demonstrates empirical viability for spiral galaxies and theoretical consistency within a geometric-thermodynamic context. The framework provides clear physical interpretation through information theory while maintaining mathematical rigor through variational principles.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"483 ","pages":"Article 170246"},"PeriodicalIF":3.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145248006","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 argue that Planck-scale fluctuations “planckeons” realize a network of non-traversable Einstein–Rosen bridges and act as holographic devices. Modeling planckeons as wormhole mouths on extremal (RT) surfaces ties spacetime connectivity directly to entanglement. Using the Ryu–Takayanagi framework, we derive an entanglement entropy that governs the thermodynamics of the planckeon ensemble. The resulting partition function exhibits a high-temperature logarithmic entropy consistent with holographic scaling, while at low temperature the network freezes into a sparse remnant-like phase. A characteristic temperature (set by the planckeon gap) separates these regimes; in the noninteracting edge-mode description this marks a crossover (and becomes a genuine phase transition once interactions/pairing are included). Embedding a minimal length in the wormhole throat yields a quantum-corrected Bekenstein entropy in which the area term is supplemented by edge-mode contributions, thereby linking wormhole geometry with quantum-information flow and suggesting a holographic origin of spacetime and black-hole microstructure.
{"title":"Planckeons as mouths of quantum wormholes and holographic origin of spacetime","authors":"Ignazio Licata , Fabrizio Tamburini , Davide Fiscaletti","doi":"10.1016/j.aop.2025.170248","DOIUrl":"10.1016/j.aop.2025.170248","url":null,"abstract":"<div><div>We argue that Planck-scale fluctuations “planckeons” realize a network of non-traversable Einstein–Rosen bridges and act as holographic devices. Modeling planckeons as wormhole mouths on extremal (RT) surfaces ties spacetime connectivity directly to entanglement. Using the Ryu–Takayanagi framework, we derive an entanglement entropy that governs the thermodynamics of the planckeon ensemble. The resulting partition function exhibits a high-temperature logarithmic entropy consistent with holographic scaling, while at low temperature the network freezes into a sparse remnant-like phase. A characteristic temperature <span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>c</mi></mrow></msub></math></span> (set by the planckeon gap) separates these regimes; in the noninteracting edge-mode description this marks a <em>crossover</em> (and becomes a genuine phase transition once interactions/pairing are included). Embedding a minimal length in the wormhole throat yields a quantum-corrected Bekenstein entropy in which the area term is supplemented by edge-mode contributions, thereby linking wormhole geometry with quantum-information flow and suggesting a holographic origin of spacetime and black-hole microstructure.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"483 ","pages":"Article 170248"},"PeriodicalIF":3.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145323003","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 : 2025-12-01Epub Date: 2025-10-01DOI: 10.1016/j.aop.2025.170241
Hao Zhu , Su-Ye Lü , Xiao-Yang Shi , Wu-Ming Liu
We report the formation of magnetic domain wall (MDW) in ferromagnetic spin-2 Bose–Einstein condensates, triggered by Raman-type spin–orbit coupling (SOC). In this study, we explore the generation and deformation of the MDW basing on both mean-field theory and hydrodynamic theory. The MDW cannot be formed by bare SOC, while emerges when rotation effect is considered. A typical kink shaped longitude magnetization and bell shaped transverse magnetization of the MDW are proposed, and the superfluid velocity field calculations indicates the MDW is topological nontrivial. The evolution of MDW with SOC is systematic studied through degree of phase separation, topological charge, and particle number transformation. Moreover, a first-order phase transition happens when rotation frequency exceeds a critical value, and novel wall–vortex complexes appear. The stability of the MDW is also discussed through real-time dynamics in the presence of Gaussian noise that MDW can survive for a long period of time with strong SOC. Our work paves the way to explore exotic topological excitations in high-spin system.
{"title":"Magnetic domain walls in Ferromagnetic Spin-2 Bose–Einstein condensates","authors":"Hao Zhu , Su-Ye Lü , Xiao-Yang Shi , Wu-Ming Liu","doi":"10.1016/j.aop.2025.170241","DOIUrl":"10.1016/j.aop.2025.170241","url":null,"abstract":"<div><div>We report the formation of magnetic domain wall (MDW) in ferromagnetic spin-2 Bose–Einstein condensates, triggered by Raman-type spin–orbit coupling (SOC). In this study, we explore the generation and deformation of the MDW basing on both mean-field theory and hydrodynamic theory. The MDW cannot be formed by bare SOC, while emerges when rotation effect is considered. A typical kink shaped longitude magnetization and bell shaped transverse magnetization of the MDW are proposed, and the superfluid velocity field calculations indicates the MDW is topological nontrivial. The evolution of MDW with SOC is systematic studied through degree of phase separation, topological charge, and particle number transformation. Moreover, a first-order phase transition happens when rotation frequency exceeds a critical value, and novel wall–vortex complexes appear. The stability of the MDW is also discussed through real-time dynamics in the presence of Gaussian noise that MDW can survive for a long period of time with strong SOC. Our work paves the way to explore exotic topological excitations in high-spin system.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"483 ","pages":"Article 170241"},"PeriodicalIF":3.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145322988","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 : 2025-12-01Epub Date: 2025-10-10DOI: 10.1016/j.aop.2025.170240
Deepak Vaid , Lin Teixeira de Sousa
We propose a modification of the Nambu–Goto action for the bosonic string which is compatible with the existence of a minimum area at the Planck scale. The result is a phenomenological action based on the observation that LQG tells us that areas of two-surfaces are operators in quantum geometry and are bounded from below. This leads us to a string action which is similar to that of bimetric gravity. We provide formulations of the bimetric string action for both the Nambu–Goto (second order) and Polyakov (first order) formulations. We explore the classical solutions of this action and its quantization and relate it to the conventional string solutions.
We further construct a string action in which the effect of the background geometry is described in terms of the pullback of the bulk connection, which encodes the bulk geometry, to the worldsheet. The resulting string action is in the form of a gauged sigma model, where the spacetime co-ordinates are now vectors which transform under the Poincaré group . This requires the introduction of an auxiliary bulk co-ordinate which has a natural interpretation as a holographic or scale direction. We discuss possible cosmological implications of such a large scale emergent dimension.
{"title":"A loop quantum gravity inspired action for the bosonic string and emergent dimensions at large scales","authors":"Deepak Vaid , Lin Teixeira de Sousa","doi":"10.1016/j.aop.2025.170240","DOIUrl":"10.1016/j.aop.2025.170240","url":null,"abstract":"<div><div>We propose a modification of the Nambu–Goto action for the bosonic string which is compatible with the existence of a minimum area at the Planck scale. The result is a phenomenological action based on the observation that LQG tells us that areas of two-surfaces are operators in quantum geometry and are bounded from below. This leads us to a string action which is similar to that of bimetric gravity. We provide formulations of the bimetric string action for both the Nambu–Goto (second order) and Polyakov (first order) formulations. We explore the classical solutions of this action and its quantization and relate it to the conventional string solutions.</div><div>We further construct a string action in which the effect of the background geometry is described in terms of the pullback of the bulk connection, which encodes the bulk geometry, to the worldsheet. The resulting string action is in the form of a gauged sigma model, where the spacetime co-ordinates are now vectors which transform under the Poincaré group <span><math><mrow><mi>I</mi><mi>S</mi><mi>O</mi><mrow><mo>(</mo><mi>D</mi><mo>,</mo><mn>1</mn><mo>)</mo></mrow></mrow></math></span>. This requires the introduction of an auxiliary bulk co-ordinate which has a natural interpretation as a holographic or scale direction. We discuss possible cosmological implications of such a large scale emergent dimension.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"483 ","pages":"Article 170240"},"PeriodicalIF":3.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145322989","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 : 2025-12-01Epub Date: 2025-10-04DOI: 10.1016/j.aop.2025.170243
Da-Wei Luo, Ting Yu
Non-Markovian effects in the dynamics of an open system are typically characterized by non-monotonic information flows from the system to its environment or by information backflows from the environment to the system. Using a two-level system (TLS) coupled to a dissipative single-mode cavity, we demonstrate that the geometric decoherence of the open quantum system can serve as a reliable indicator of non-Markovian dynamics. This geometric approach also reveals finer details of the dynamics, such as the specific time points when non-Markovian behavior emerges. In particular, we show that the divergence of the geometric decoherence factor of the TLS can serve as a sufficient condition for non-Markovian dynamics, and in certain cases, it can even be both a necessary and sufficient condition.
{"title":"Geometric signature of non-Markovian dynamics","authors":"Da-Wei Luo, Ting Yu","doi":"10.1016/j.aop.2025.170243","DOIUrl":"10.1016/j.aop.2025.170243","url":null,"abstract":"<div><div>Non-Markovian effects in the dynamics of an open system are typically characterized by non-monotonic information flows from the system to its environment or by information backflows from the environment to the system. Using a two-level system (TLS) coupled to a dissipative single-mode cavity, we demonstrate that the geometric decoherence of the open quantum system can serve as a reliable indicator of non-Markovian dynamics. This geometric approach also reveals finer details of the dynamics, such as the specific time points when non-Markovian behavior emerges. In particular, we show that the divergence of the geometric decoherence factor of the TLS can serve as a sufficient condition for non-Markovian dynamics, and in certain cases, it can even be both a necessary and sufficient condition.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"483 ","pages":"Article 170243"},"PeriodicalIF":3.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145248007","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 : 2025-12-01Epub Date: 2025-10-29DOI: 10.1016/j.aop.2025.170270
Chia-Yi Ju , Junting He , Guang-Yin Chen
Exceptional points (EPs) in non-Hermitian systems exhibit intriguing properties, particularly in their eigenvalue perturbative expansions. Unlike standard perturbation theory, where perturbed eigenvalues can be expanded in a power series of the perturbation parameter, at an th-order EP, the perturbed eigenvalues are generally expanded in th-root of the perturbation parameter, indicating the nonanalytical nature of EPs. Since studies have suggested that the exponent of the perturbation parameter in the first-order term of the eigenvalue perturbation is related to the topological properties of the Hilbert space bundle, understanding this exponent is important. Therefore, in this study, we first demonstrate that the leading order in the perturbation correction is related to the topology of the Hilbert space bundle. We then show that the perturbative behavior, and hence the topology, not only depends on the order of the EP but can also be affected by the rest of the system. We show that the exponent of the expansion parameters in the leading order of eigenvalue expansions at an th-order EP can be a fractional number differs from under special circumstances. These results may contribute to identifying the topology of the Hilbert space bundle, offer a new perspective to the formulation of perturbation theory around EPs, and provide further insights into non-Hermitian quantum systems.
{"title":"Fractional exponents and topological signatures of exceptional points in non-Hermitian systems","authors":"Chia-Yi Ju , Junting He , Guang-Yin Chen","doi":"10.1016/j.aop.2025.170270","DOIUrl":"10.1016/j.aop.2025.170270","url":null,"abstract":"<div><div>Exceptional points (EPs) in non-Hermitian systems exhibit intriguing properties, particularly in their eigenvalue perturbative expansions. Unlike standard perturbation theory, where perturbed eigenvalues can be expanded in a power series of the perturbation parameter, at an <span><math><mi>N</mi></math></span>th-order EP, the perturbed eigenvalues are generally expanded in <span><math><mi>N</mi></math></span>th-root of the perturbation parameter, indicating the nonanalytical nature of EPs. Since studies have suggested that the exponent of the perturbation parameter in the first-order term of the eigenvalue perturbation is related to the topological properties of the Hilbert space bundle, understanding this exponent is important. Therefore, in this study, we first demonstrate that the leading order in the perturbation correction is related to the topology of the Hilbert space bundle. We then show that the perturbative behavior, and hence the topology, not only depends on the order of the EP but can also be affected by the rest of the system. We show that the exponent of the expansion parameters in the leading order of eigenvalue expansions at an <span><math><mi>N</mi></math></span>th-order EP can be a fractional number differs from <span><math><mrow><mn>1</mn><mo>/</mo><mi>N</mi></mrow></math></span> under special circumstances. These results may contribute to identifying the topology of the Hilbert space bundle, offer a new perspective to the formulation of perturbation theory around EPs, and provide further insights into non-Hermitian quantum systems.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"483 ","pages":"Article 170270"},"PeriodicalIF":3.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145413809","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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