Pub Date : 2025-11-20DOI: 10.1016/j.aop.2025.170297
Kourosh Nozari, Hamed Ramezani
In this paper, we study the statistical mechanics within the polymer quantization framework in the semiclassical regime. We apply a non-canonical transformation to the phase space variables. Then, we use this non-canonical transformation to calculate the deformed density of states of the -dimensional phase space, which encompasses all polymer effects. In the next step, some thermodynamic features of a system of -dimensional harmonic oscillators are studied by computing the deformed partition function. The results show that the number of microstates decreases because there is an upper bound on the momentum within the polymer framework. We found that in the high-temperature regime, when the thermal de Broglie wavelength is close to the Planck length, degrees of freedom of the system are frozen in this setup. In other words, there is an effective reduction in space dimensions from to in the polymeric framework, which also signals the fractional dimension for odd-dimensional oscillators.
{"title":"Dimensional phenomenology in polymeric quantization framework","authors":"Kourosh Nozari, Hamed Ramezani","doi":"10.1016/j.aop.2025.170297","DOIUrl":"10.1016/j.aop.2025.170297","url":null,"abstract":"<div><div>In this paper, we study the statistical mechanics within the polymer quantization framework in the semiclassical regime. We apply a non-canonical transformation to the phase space variables. Then, we use this non-canonical transformation to calculate the deformed density of states of the <span><math><mrow><mn>2</mn><mi>n</mi></mrow></math></span>-dimensional phase space, which encompasses all polymer effects. In the next step, some thermodynamic features of a system of <span><math><mi>n</mi></math></span>-dimensional harmonic oscillators are studied by computing the deformed partition function. The results show that the number of microstates decreases because there is an upper bound on the momentum within the polymer framework. We found that in the high-temperature regime, when the thermal de Broglie wavelength is close to the Planck length, <span><math><mi>n</mi></math></span> degrees of freedom of the system are frozen in this setup. In other words, there is an effective reduction in space dimensions from <span><math><mi>n</mi></math></span> to <span><math><mfrac><mrow><mi>n</mi></mrow><mrow><mn>2</mn></mrow></mfrac></math></span> in the polymeric framework, which also signals the fractional dimension for odd-dimensional oscillators.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"484 ","pages":"Article 170297"},"PeriodicalIF":3.0,"publicationDate":"2025-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145577898","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 : 2025-11-20DOI: 10.1016/j.aop.2025.170296
O. Hryhorchak , G. Panochko , V. Pastukhov
The properties of the one-dimensional population-imbalanced fermions are discussed. First, the system is assumed to be in the two-body resonance where all two-body scattering lengths diverge, and the only interaction between fermions that is taken into account is the short-range three-body one. In particular, we consider the situation when only one ‘flavor’ of fermions is macroscopically occupied, and there are exactly two atoms of the other two. This system supports the trimer and the medium-induced dimer states studied here in detail and shows evidence of color superfluidity. The impact of the two-body inter-impurity interaction that breaks the initial symmetry on the properties of the bipolaron is revealed.
{"title":"Bipolaron in one-dimensional fermions with three-body interaction","authors":"O. Hryhorchak , G. Panochko , V. Pastukhov","doi":"10.1016/j.aop.2025.170296","DOIUrl":"10.1016/j.aop.2025.170296","url":null,"abstract":"<div><div>The properties of the one-dimensional <span><math><mrow><mi>S</mi><mi>U</mi><mrow><mo>(</mo><mn>3</mn><mo>)</mo></mrow></mrow></math></span> population-imbalanced fermions are discussed. First, the system is assumed to be in the two-body resonance where all two-body scattering lengths diverge, and the only interaction between fermions that is taken into account is the short-range three-body one. In particular, we consider the situation when only one ‘flavor’ of fermions is macroscopically occupied, and there are exactly two atoms of the other two. This system supports the trimer and the medium-induced dimer states studied here in detail and shows evidence of color superfluidity. The impact of the two-body inter-impurity interaction that breaks the initial <span><math><mrow><mi>S</mi><mi>U</mi><mrow><mo>(</mo><mn>3</mn><mo>)</mo></mrow></mrow></math></span> symmetry on the properties of the bipolaron is revealed.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"484 ","pages":"Article 170296"},"PeriodicalIF":3.0,"publicationDate":"2025-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145577952","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 : 2025-11-20DOI: 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":"2025-11-20","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 : 2025-11-17DOI: 10.1016/j.aop.2025.170291
Arun Kumar , Sushant G. Ghosh
We investigate the strong gravitational lensing signatures of black holes (BH) surrounded by a novel class of cloud of strings (NCoS), characterized by additional parameters and beyond the Schwarzschild case. After deriving the photon sphere and critical impact parameter, we investigate the deflection angle in the strong-field regime, showing logarithmic divergence near the photon orbit. The lensing observables—angular image positions (), flux ratios (), and time delays between relativistic images—are computed for supermassive BHs M87 and Sgr A. Compared to Schwarzschild, Reissner-Nordström, and Letelier BHs, NCoS spacetime reveals distinguishable lensing features, with photon sphere radii and Einstein ring diameters varying non-monotonically with and . Applying our formalism to supermassive black holes M87* and Sgr A*, we find that the angular size of the photon ring and flux ratio provide stringent constraints on the NCoS parameters. EHT observations of M87* restrict the string cloud parameter to , while Sgr A* data impose tighter bounds () with , ruling out the pure Letelier limit () at confidence. Our results illustrate that NCoS BHs reconcile with EHT observations for a broader parameter range than earlier models, offering a viable framework to probe string-inspired modifications to general relativity in the strong-gravity regime.
我们研究了被一类新的弦云（NCoS）包围的黑洞（BH）的强引力透镜特征，其特征是超出史瓦西情况的附加参数|、|和c0。在推导出光子球和临界撞击参数后，我们研究了在强场区域的偏转角，在光子轨道附近显示出对数发散。透镜观测值——角图像位置（θ∞）、通量比（rmag）和相对论图像之间的时间延迟——计算了超大质量黑洞M87∗和Sgr A∗。与史瓦西黑洞、Reissner-Nordström和Letelier黑洞相比，NCoS时空显示出明显的透镜特征，光子球半径和爱因斯坦环直径随|、|和c0呈非单调变化。将我们的公式应用于超大质量黑洞M87*和Sgr A*，我们发现光子环的角尺寸θ∞和通量比rma对NCoS参数有严格的约束。M87*的EHT观测将弦云参数限制在0≤|a|≤0.56，而Sgr a *的数据在c0/M≥1.57的情况下施加了更严格的界限（|a|≤0.42），排除了纯Letelier极限（c0→0）在>；2σ置信度。我们的研究结果表明，与早期模型相比，NCoS黑洞在更宽的参数范围内与EHT观测相吻合，为探索强引力条件下弦启发的广义相对论修正提供了一个可行的框架。
{"title":"Strong gravitational lensing by black holes with a cloud of strings and constraints from EHT observations of M87* and Sgr A*","authors":"Arun Kumar , Sushant G. Ghosh","doi":"10.1016/j.aop.2025.170291","DOIUrl":"10.1016/j.aop.2025.170291","url":null,"abstract":"<div><div>We investigate the strong gravitational lensing signatures of black holes (BH) surrounded by a novel class of cloud of strings (NCoS), characterized by additional parameters <span><math><mrow><mo>|</mo><mi>a</mi><mo>|</mo></mrow></math></span> and <span><math><msub><mrow><mi>c</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span> beyond the Schwarzschild case. After deriving the photon sphere and critical impact parameter, we investigate the deflection angle in the strong-field regime, showing logarithmic divergence near the photon orbit. The lensing observables—angular image positions (<span><math><msub><mrow><mi>θ</mi></mrow><mrow><mi>∞</mi></mrow></msub></math></span>), flux ratios (<span><math><msub><mrow><mi>r</mi></mrow><mrow><mtext>mag</mtext></mrow></msub></math></span>), and time delays between relativistic images—are computed for supermassive BHs M87<span><math><msup><mrow></mrow><mrow><mo>∗</mo></mrow></msup></math></span> and Sgr A<span><math><msup><mrow></mrow><mrow><mo>∗</mo></mrow></msup></math></span>. Compared to Schwarzschild, Reissner-Nordström, and Letelier BHs, NCoS spacetime reveals distinguishable lensing features, with photon sphere radii and Einstein ring diameters varying non-monotonically with <span><math><mrow><mo>|</mo><mi>a</mi><mo>|</mo></mrow></math></span> and <span><math><msub><mrow><mi>c</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span>. Applying our formalism to supermassive black holes M87* and Sgr A*, we find that the angular size of the photon ring <span><math><msub><mrow><mi>θ</mi></mrow><mrow><mi>∞</mi></mrow></msub></math></span> and flux ratio <span><math><msub><mrow><mi>r</mi></mrow><mrow><mtext>mag</mtext></mrow></msub></math></span> provide stringent constraints on the NCoS parameters. EHT observations of M87* restrict the string cloud parameter to <span><math><mrow><mn>0</mn><mo>≤</mo><mrow><mo>|</mo><mi>a</mi><mo>|</mo></mrow><mo>≤</mo><mn>0</mn><mo>.</mo><mn>56</mn></mrow></math></span>, while Sgr A* data impose tighter bounds (<span><math><mrow><mrow><mo>|</mo><mi>a</mi><mo>|</mo></mrow><mo>≤</mo><mn>0</mn><mo>.</mo><mn>42</mn></mrow></math></span>) with <span><math><mrow><msub><mrow><mi>c</mi></mrow><mrow><mn>0</mn></mrow></msub><mo>/</mo><mi>M</mi><mo>≳</mo><mn>1</mn><mo>.</mo><mn>57</mn></mrow></math></span>, ruling out the pure Letelier limit (<span><math><mrow><msub><mrow><mi>c</mi></mrow><mrow><mn>0</mn></mrow></msub><mo>→</mo><mn>0</mn></mrow></math></span>) at <span><math><mrow><mo>></mo><mn>2</mn><mi>σ</mi></mrow></math></span> confidence. Our results illustrate that NCoS BHs reconcile with EHT observations for a broader parameter range than earlier models, offering a viable framework to probe string-inspired modifications to general relativity in the strong-gravity regime.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"484 ","pages":"Article 170291"},"PeriodicalIF":3.0,"publicationDate":"2025-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145577951","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 : 2025-11-15DOI: 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.
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