Pub 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":"2025-11-15","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}
This investigation provides a meticulous and profound analysis of gravastar configurations within the framework of gravity, incorporating the Mazur Mottola formalism in conjunction with the temporal component of the Tolman-IV ansatz. The structure under consideration is delineated by a central region dominated by an exotic energy density, encased within an ultra-relativistic shell and culminating in a Schwarzschild exterior. Our treatment is anchored in the study of two gravastar models, uniquely distinguished by their respective mass–radius profiles. The analysis pursues a rigorous exploration of the shell’s internal features, with emphasis placed upon its finite thickness, energy density stratification and governing equation of state. The role of the coupling parameter is examined within the domain , wherein the limiting case reproduces the conventional predictions of general relativity. In addition, a three-dimensional graphical exploration illustrates the stabilizing capacity of , thereby consolidating the structural integrity and astrophysical viability of gravastars in the wider context of modified gravity frameworks.
{"title":"Structural evolution of gravastars under Tolman-IV metric in F(R,T) gravity","authors":"Arfa Waseem , A. Eid , Salma Yaqoob , Faisal Javed","doi":"10.1016/j.aop.2025.170289","DOIUrl":"10.1016/j.aop.2025.170289","url":null,"abstract":"<div><div>This investigation provides a meticulous and profound analysis of gravastar configurations within the framework of <span><math><mrow><mi>F</mi><mrow><mo>(</mo><mi>R,T</mi><mo>)</mo></mrow></mrow></math></span> gravity, incorporating the Mazur Mottola formalism in conjunction with the temporal component of the Tolman-IV ansatz. The structure under consideration is delineated by a central region dominated by an exotic energy density, encased within an ultra-relativistic shell and culminating in a Schwarzschild exterior. Our treatment is anchored in the study of two gravastar models, uniquely distinguished by their respective mass–radius profiles. The analysis pursues a rigorous exploration of the shell’s internal features, with emphasis placed upon its finite thickness, energy density stratification and governing equation of state. The role of the coupling parameter <span><math><mi>α</mi></math></span> is examined within the domain <span><math><mrow><mn>0</mn><mo>≤</mo><mi>α</mi><mo><</mo><mn>1</mn></mrow></math></span>, wherein the limiting case <span><math><mrow><mi>α</mi><mo>→</mo><mn>0</mn></mrow></math></span> reproduces the conventional predictions of general relativity. In addition, a three-dimensional graphical exploration illustrates the stabilizing capacity of <span><math><mi>α</mi></math></span>, thereby consolidating the structural integrity and astrophysical viability of gravastars in the wider context of modified gravity frameworks.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"484 ","pages":"Article 170289"},"PeriodicalIF":3.0,"publicationDate":"2025-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145577953","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 : 2025-11-10DOI: 10.1016/j.aop.2025.170250
Jens Braun , Andreas Geißel , Jan M. Pawlowski , Franz R. Sattler , Nicolas Wink
Systematic expansion schemes in functional approaches require the inclusion of non-classical tensor structures for relevant vertices. Each vertex has to be expanded in an appropriate tensor basis with a rapidly increasing number of basis elements. In contrast, classical actions typically only contain one of many tensor structures of a given vertex. Among the related tasks are the construction of bases and projection operators, the importance ordering of their elements, and the optimisation of such tensor bases, as well as an analysis of their regularity in momentum space. We present progress in all these directions and introduce the Mathematica package TensorBases designed for the aforementioned tasks.
{"title":"Juggling with tensor bases in functional approaches","authors":"Jens Braun , Andreas Geißel , Jan M. Pawlowski , Franz R. Sattler , Nicolas Wink","doi":"10.1016/j.aop.2025.170250","DOIUrl":"10.1016/j.aop.2025.170250","url":null,"abstract":"<div><div>Systematic expansion schemes in functional approaches require the inclusion of non-classical tensor structures for relevant vertices. Each vertex has to be expanded in an appropriate tensor basis with a rapidly increasing number of basis elements. In contrast, classical actions typically only contain one of many tensor structures of a given vertex. Among the related tasks are the construction of bases and projection operators, the importance ordering of their elements, and the optimisation of such tensor bases, as well as an analysis of their regularity in momentum space. We present progress in all these directions and introduce the Mathematica package <span><span>TensorBases</span><svg><path></path></svg></span> designed for the aforementioned tasks.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"484 ","pages":"Article 170250"},"PeriodicalIF":3.0,"publicationDate":"2025-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145577894","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 : 2025-11-10DOI: 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":"2025-11-10","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 : 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":"2025-11-07","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 : 2025-11-01DOI: 10.1016/j.aop.2025.170277
S. Habib Mazharimousavi
Motivated by developments in Loop Quantum Cosmology (LQC) and quantum-corrected black holes, we propose a cosmological black/white hole model in which a traveler can enter a black hole and emerge from a white hole without ever encountering a singularity. Our construction is based on the Reissner–Nordström (RN) black hole, which naturally possesses a timelike singularity. By employing the thin-shell wormhole (TSW) formalism, we demonstrate how the interior can be surgically modified to connect a black hole region to a white hole region. We analyze the junction conditions and identify the exotic surface matter required at the throat. Furthermore, we investigate the stability of the throat under linear mechanical perturbations and show that stability is achievable for throat radii smaller than a critical value. Our results illustrate, at a phenomenological level, the feasibility of constructing nonsingular black/white hole transitions, shedding light on possible quantum-gravity inspired alternatives to classical singularities.
{"title":"From black hole to white hole via thin-shell wormhole","authors":"S. Habib Mazharimousavi","doi":"10.1016/j.aop.2025.170277","DOIUrl":"10.1016/j.aop.2025.170277","url":null,"abstract":"<div><div>Motivated by developments in Loop Quantum Cosmology (LQC) and quantum-corrected black holes, we propose a cosmological black/white hole model in which a traveler can enter a black hole and emerge from a white hole without ever encountering a singularity. Our construction is based on the Reissner–Nordström (RN) black hole, which naturally possesses a timelike singularity. By employing the thin-shell wormhole (TSW) formalism, we demonstrate how the interior can be surgically modified to connect a black hole region to a white hole region. We analyze the junction conditions and identify the exotic surface matter required at the throat. Furthermore, we investigate the stability of the throat under linear mechanical perturbations and show that stability is achievable for throat radii smaller than a critical value. Our results illustrate, at a phenomenological level, the feasibility of constructing nonsingular black/white hole transitions, shedding light on possible quantum-gravity inspired alternatives to classical singularities.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"483 ","pages":"Article 170277"},"PeriodicalIF":3.0,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145463423","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}
This study investigates the effects of Hawking radiation on tripartite quantum coherence and tripartite entropy uncertainty measurement in the context of a Schwarzschild black hole. Two main cases are examined, each encompassing three distinct scenarios: one involving only accessible modes (particles outside the event horizon), another involving only inaccessible modes (antiparticles inside the event horizon), and a third involving both accessible and inaccessible modes. Results show that in scenarios with accessible modes, tripartite quantum coherence decreases monotonically with increasing Hawking temperature, while tripartite entropy uncertainty measurement rises. Conversely, when inaccessible modes are present, Hawking radiation generates quantum coherence and reduces entropy uncertainty measurement. This suggests that quantum coherence and measurement uncertainty can be transmitted or distributed across different regions of spacetime, even across the event horizon of a black hole, indicating an interconnection of quantum properties despite the horizon’s role as a boundary.
{"title":"The effect of Hawking radiation on tripartite entropic uncertainty and tripartite Quantum coherence in Schwarzschild spacetime","authors":"Wajid Joyia , Asif Ilyas , Mahtab A. Khan , Nahaa Eid Alsubaie , Amaria Javed","doi":"10.1016/j.aop.2025.170269","DOIUrl":"10.1016/j.aop.2025.170269","url":null,"abstract":"<div><div>This study investigates the effects of Hawking radiation on tripartite quantum coherence and tripartite entropy uncertainty measurement in the context of a Schwarzschild black hole. Two main cases are examined, each encompassing three distinct scenarios: one involving only accessible modes (particles outside the event horizon), another involving only inaccessible modes (antiparticles inside the event horizon), and a third involving both accessible and inaccessible modes. Results show that in scenarios with accessible modes, tripartite quantum coherence decreases monotonically with increasing Hawking temperature, while tripartite entropy uncertainty measurement rises. Conversely, when inaccessible modes are present, Hawking radiation generates quantum coherence and reduces entropy uncertainty measurement. This suggests that quantum coherence and measurement uncertainty can be transmitted or distributed across different regions of spacetime, even across the event horizon of a black hole, indicating an interconnection of quantum properties despite the horizon’s role as a boundary.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"483 ","pages":"Article 170269"},"PeriodicalIF":3.0,"publicationDate":"2025-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145463424","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 phase sensitivity of a Mach–Zehnder interferometer using a special class of generalized coherent states constructed from generalized Heisenberg and deformed algebras. These states, derived from a perturbed harmonic oscillator with a four-parameter deformed spectrum, provide enhanced tunability and nonclassical features. The quantum Fisher information and its associated quantum Cramér–Rao bound are computed to define the fundamental precision limits in phase estimation. We analyze the phase sensitivity under three realistic detection methods: difference intensity detection, single-mode intensity detection, and balanced homodyne detection. The performance of each method is compared with the quantum Cramér–Rao bound to evaluate their optimality. Our results demonstrate that, for suitable parameter regimes, these generalized coherent states enable phase sensitivities approaching the quantum limit. This offers a flexible framework for precision quantum metrology and potential applications in quantum-enhanced sensing.
{"title":"Quantum phase sensitivity with generalized coherent states based on deformed su(1,1) and Heisenberg algebras","authors":"Nour-Eddine Abouelkhir , Abdallah Slaoui , Rachid Ahl Laamara","doi":"10.1016/j.aop.2025.170276","DOIUrl":"10.1016/j.aop.2025.170276","url":null,"abstract":"<div><div>We investigate the phase sensitivity of a Mach–Zehnder interferometer using a special class of generalized coherent states constructed from generalized Heisenberg and deformed <span><math><mrow><mi>s</mi><mi>u</mi><mrow><mo>(</mo><mn>1</mn><mo>,</mo><mn>1</mn><mo>)</mo></mrow></mrow></math></span> algebras. These states, derived from a perturbed harmonic oscillator with a four-parameter deformed spectrum, provide enhanced tunability and nonclassical features. The quantum Fisher information and its associated quantum Cramér–Rao bound are computed to define the fundamental precision limits in phase estimation. We analyze the phase sensitivity under three realistic detection methods: difference intensity detection, single-mode intensity detection, and balanced homodyne detection. The performance of each method is compared with the quantum Cramér–Rao bound to evaluate their optimality. Our results demonstrate that, for suitable parameter regimes, these generalized coherent states enable phase sensitivities approaching the quantum limit. This offers a flexible framework for precision quantum metrology and potential applications in quantum-enhanced sensing.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"483 ","pages":"Article 170276"},"PeriodicalIF":3.0,"publicationDate":"2025-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145413810","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 : 2025-10-30DOI: 10.1016/j.aop.2025.170267
Matteo Baggioli , Maxim N. Chernodub , Karl Landsteiner , Alessandro Principi , María A.H. Vozmediano
The dynamics of Dirac semimetals is modeled at low energies by the massless Dirac Hamiltonian with the Fermi velocity replacing the velocity of light. The classical action is scale invariant. In 3D materials, Coulomb interactions induce a conformal anomaly associated to the charge renormalization already known in quantum field theory. In this work, we describe a new conformal anomaly induced by the running of the Fermi velocity that applies to Dirac semimetals in two and three dimensions. The case of graphene is particularly interesting. We analyze the anomaly and explore its thermodynamic and hydrodynamic consequences. The anomaly changes the thermodynamic equation of state of the systems and modifies the propagation speed of hydrodynamic sound waves experimentally accessible.
{"title":"A conformal anomaly from the Fermi velocity renormalization in graphene and Dirac semi-metals","authors":"Matteo Baggioli , Maxim N. Chernodub , Karl Landsteiner , Alessandro Principi , María A.H. Vozmediano","doi":"10.1016/j.aop.2025.170267","DOIUrl":"10.1016/j.aop.2025.170267","url":null,"abstract":"<div><div>The dynamics of Dirac semimetals is modeled at low energies by the massless Dirac Hamiltonian with the Fermi velocity replacing the velocity of light. The classical action is scale invariant. In 3D materials, Coulomb interactions induce a conformal anomaly associated to the charge renormalization already known in quantum field theory. In this work, we describe a new conformal anomaly induced by the running of the Fermi velocity that applies to Dirac semimetals in two and three dimensions. The case of graphene is particularly interesting. We analyze the anomaly and explore its thermodynamic and hydrodynamic consequences. The anomaly changes the thermodynamic equation of state of the systems and modifies the propagation speed of hydrodynamic sound waves experimentally accessible.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"483 ","pages":"Article 170267"},"PeriodicalIF":3.0,"publicationDate":"2025-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145413811","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 : 2025-10-29DOI: 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":"2025-10-29","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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