Fortschritte Der Physik-Progress of Physics最新文献

{"title":"Is Phantom Divide Crossing in General Relativity Completely Impossible? Shortcomings in Canonical and Minimally Coupled Scalar Field and Possible Solutions in k-Essence Models","authors":"Shin'ichi Nojiri,&nbsp;S.D. Odintsov,&nbsp;V.K. Oikonomou","doi":"10.1002/prop.70137","DOIUrl":"https://doi.org/10.1002/prop.70137","url":null,"abstract":"<div>\u0000 \u0000 <p>General relativity has its successes at the local astrophysical level, however, it seems to be insufficient in describing the Universe at large scales. In this work, we investigate how the generalized scalar field theories in the context of general relativity can accommodate a phantom-to-quintessence transition, which may be an essential element of realistic Dark Energy scenarios in the late Universe. As we demonstrate in a very detailed manner, this is impossible for a canonical and minimally coupled single scalar field theory, but it may be possible for <span></span><math>\u0000 <semantics>\u0000 <mi>k</mi>\u0000 <annotation>$k$</annotation>\u0000 </semantics></math>-essence theories. We point out how the ghost instabilities may be eliminated, and we analyze the quantitative features of a <span></span><math>\u0000 <semantics>\u0000 <mi>k</mi>\u0000 <annotation>$k$</annotation>\u0000 </semantics></math>-essence theory that may realize a phantom-to-quintessence transition in the late Universe. We also qualitatively compare the difficulties and fine-tunings required for <span></span><math>\u0000 <semantics>\u0000 <mi>k</mi>\u0000 <annotation>$k$</annotation>\u0000 </semantics></math>-essence theories to realize a phantom-to-quintessence transition, and how such a transition is naturally realized in modified gravity, without unnecessary fine-tunings and ghost eliminations.</p></div>","PeriodicalId":55150,"journal":{"name":"Fortschritte Der Physik-Progress of Physics","volume":"74 8","pages":""},"PeriodicalIF":5.4,"publicationDate":"2026-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148652416","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}

{"title":"Bianchi I Spacetimes in f(Q)-Gravity","authors":"Andronikos Paliathanasis,&nbsp;Genly Leon","doi":"10.1002/prop.70133","DOIUrl":"https://doi.org/10.1002/prop.70133","url":null,"abstract":"<p>The Kasner spacetimes are exact solutions that are self-similar and of significant interest because they can describe the dynamic evolution of kinematic variables near the singularity of the Mixmaster universe. The chaotic behavior of the Mixmaster universe is related to the Kasner relations. This study investigates Kasner and Kasner-like solutions in symmetric teleparallel <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>f</mi>\u0000 <mfenced>\u0000 <mi>Q</mi>\u0000 </mfenced>\u0000 </mrow>\u0000 <annotation>$fleft(Qright)$</annotation>\u0000 </semantics></math>-gravity. We consider three families of connections for the spatially flat Friedmann–Lemaître–Robertson–Walker. We found that Kasner-like solutions are present in the theory when the nonmetricity scalar <span></span><math>\u0000 <semantics>\u0000 <mi>Q</mi>\u0000 <annotation>$Q$</annotation>\u0000 </semantics></math> vanishes. Kasner-like relations are introduced only for the field equations of the connection defined in the coincident gauge. Finally, we perform a detailed phase-space analysis to understand the dynamics of <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>f</mi>\u0000 <mfenced>\u0000 <mi>Q</mi>\u0000 </mfenced>\u0000 </mrow>\u0000 <annotation>$fleft(Qright)$</annotation>\u0000 </semantics></math>-gravity in the evolution of anisotropies and the effects of different connections on this evolution.</p>","PeriodicalId":55150,"journal":{"name":"Fortschritte Der Physik-Progress of Physics","volume":"74 8","pages":""},"PeriodicalIF":5.4,"publicationDate":"2026-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/prop.70133","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148652439","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Issue Information: Fortschritte der Physik 8 / 2026","authors":"","doi":"10.1002/prop.70143","DOIUrl":"https://doi.org/10.1002/prop.70143","url":null,"abstract":"","PeriodicalId":55150,"journal":{"name":"Fortschritte Der Physik-Progress of Physics","volume":"74 8","pages":""},"PeriodicalIF":5.4,"publicationDate":"2026-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/prop.70143","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148652436","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Perturbative Analytical Construction of Bowen–York Initial Data for Binary Black Holes up to Third Order in Spin and Linear Momentum","authors":"Leyla Ogurol,&nbsp;Tore Boybeyi,&nbsp;Bayram Tekin","doi":"10.1002/prop.70136","DOIUrl":"https://doi.org/10.1002/prop.70136","url":null,"abstract":"<p>We analytically construct initial data for binary black hole systems by solving the Einstein constraint equations within the Bowen–York framework. Allowing for arbitrarily oriented linear momenta and spins, we obtain a perturbative solution of the vacuum Hamiltonian constraint up to third order in the source parameters. Our solution explicitly incorporates the system's binary nature via position-weighted multipole moments. The momentum constraints are solved exactly, while the conformal factor is determined analytically. Using the resulting initial data, we compute the ADM energy, linear and angular momenta, and the irreducible mass. We also determine the shape of the apparent horizon and show that it is geometrically consistent with the inner-end regularity. The resulting expressions are written in a manifestly tensorial form and provide an analytic benchmark for numerical–relativity calculations within the perturbative far-zone regime considered here.</p>","PeriodicalId":55150,"journal":{"name":"Fortschritte Der Physik-Progress of Physics","volume":"74 8","pages":""},"PeriodicalIF":5.4,"publicationDate":"2026-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/prop.70136","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148652417","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Radial Oscillations of Quark Stars in Light of Current Astrophysical Constraints: A Comparative Study","authors":"Grigoris Panotopoulos,&nbsp;Ángel Rincón,&nbsp;Ilidio Lopes","doi":"10.1002/prop.70132","DOIUrl":"https://doi.org/10.1002/prop.70132","url":null,"abstract":"<div>\u0000 \u0000 <p>We investigate the structural and oscillatory properties of isotropic strange quark stars within general relativity, focusing on three physically motivated equations of state: the color-flavor-locked (CFL) phase, an interacting quark matter model, and a linear (causal) equation of state. By numerically solving the Tolman–Oppenheimer–Volkoff and radial perturbation equations, we construct equilibrium stellar sequences and compute oscillation spectra across three representative masses (0.77, 1.4, and 2.0 <span></span><math>\u0000 <semantics>\u0000 <msub>\u0000 <mi>M</mi>\u0000 <mo>⊙</mo>\u0000 </msub>\u0000 <annotation>$M_odot$</annotation>\u0000 </semantics></math>). Our analysis is focused on two diagnostics: (i) mass–radius profiles and (ii) radial mode eigenfrequencies with large frequency separations. We compare theoretical predictions against multi-messenger constraints from NICER X-ray timing of key pulsars, the massive pulsars at two solar masses, and the low-mass compact object in HESS J1731−347. All three equations of state yield maximum masses exceeding 2 <span></span><math>\u0000 <semantics>\u0000 <msub>\u0000 <mi>M</mi>\u0000 <mo>⊙</mo>\u0000 </msub>\u0000 <annotation>$M_odot$</annotation>\u0000 </semantics></math> with canonical-mass radii of <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <mn>10</mn>\u0000 <mo>−</mo>\u0000 <mn>12</mn>\u0000 <mo>)</mo>\u0000 <mspace></mspace>\u0000 <mi>k</mi>\u0000 <mi>m</mi>\u0000 </mrow>\u0000 <annotation>$(10{-}12)nobreakspace km$</annotation>\u0000 </semantics></math>, satisfying current observational bounds. Fundamental mode frequencies span 4–7 kHz, with asymptotic large separations differing among the models. These elevated frequencies lie within the detection band of current and next-generation gravitational-wave observatories, offering potential asteroseismic signatures for distinguishing strange quark stars from hadronic neutron stars in post-merger emission. Our results demonstrate that self-bound quark matter naturally accommodates the sub-solar mass configuration of HESS J1731−347, reinforcing the viability of strange quark star interpretations.</p>\u0000 </div>","PeriodicalId":55150,"journal":{"name":"Fortschritte Der Physik-Progress of Physics","volume":"74 7","pages":""},"PeriodicalIF":5.4,"publicationDate":"2026-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148615608","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}

{"title":"Big Bang Nucleosynthesis in Constrained f(Q,C) Gravity: An Observational Analysis","authors":"Manahil Ali,&nbsp;A. Eid,&nbsp;Abdul Malik Sultan,&nbsp;M. Umair Shahzad","doi":"10.1002/prop.70134","DOIUrl":"https://doi.org/10.1002/prop.70134","url":null,"abstract":"&lt;div&gt;\u0000 \u0000 &lt;p&gt;The construction of &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;f&lt;/mi&gt;\u0000 &lt;mo&gt;(&lt;/mo&gt;\u0000 &lt;mi&gt;Q&lt;/mi&gt;\u0000 &lt;mo&gt;,&lt;/mo&gt;\u0000 &lt;mi&gt;C&lt;/mi&gt;\u0000 &lt;mo&gt;)&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt;$f(Q,C)$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; gravity is based on symmetric teleparallel geometry, which involves the boundary term &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mi&gt;C&lt;/mi&gt;\u0000 &lt;annotation&gt;$C$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; despite the Ricci scalar &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mi&gt;R&lt;/mi&gt;\u0000 &lt;annotation&gt;$R$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; along with non-metricity &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mi&gt;Q&lt;/mi&gt;\u0000 &lt;annotation&gt;$Q$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;. In this article, we are devoted to assess the effects of &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;f&lt;/mi&gt;\u0000 &lt;mo&gt;(&lt;/mo&gt;\u0000 &lt;mi&gt;Q&lt;/mi&gt;\u0000 &lt;mo&gt;,&lt;/mo&gt;\u0000 &lt;mi&gt;C&lt;/mi&gt;\u0000 &lt;mo&gt;)&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt;$f(Q,C)$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; gravity for the formation of light elements in the early-universe known as big bang nucleosynthesis. For instance, we examine the big bang nucleosynthesis constraints in four distinct &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;f&lt;/mi&gt;\u0000 &lt;mo&gt;(&lt;/mo&gt;\u0000 &lt;mi&gt;Q&lt;/mi&gt;\u0000 &lt;mo&gt;,&lt;/mo&gt;\u0000 &lt;mi&gt;C&lt;/mi&gt;\u0000 &lt;mo&gt;)&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt;$f(Q,C)$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; gravity models. Specifically, we investigate how the modifications by the boundary term &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mi&gt;C&lt;/mi&gt;\u0000 &lt;annotation&gt;$C$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; and non-metricity &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mi&gt;Q&lt;/mi&gt;\u0000 &lt;annotation&gt;$Q$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; influence the freeze-out temperature &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;T&lt;/mi&gt;\u0000 &lt;mi&gt;f&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;annotation&gt;$mathcal {T}_f$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;, comparing with the standard &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;Λ&lt;/mi&gt;\u0000 &lt;mi&gt;CDM&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt;$Lambda{rm CDM}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; results. We focus on four distinct cosmological models of &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;f&lt;/mi&gt;\u0000 ","PeriodicalId":55150,"journal":{"name":"Fortschritte Der Physik-Progress of Physics","volume":"74 7","pages":""},"PeriodicalIF":5.4,"publicationDate":"2026-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148466818","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}

{"title":"Holographic Weyl Anomaly and Kounterterms in AdS Gravity","authors":"Giorgos Anastasiou,&nbsp;Jahaira Bonifacio-Chavez,&nbsp;Olivera Miskovic,&nbsp;Rodrigo Olea","doi":"10.1002/prop.70130","DOIUrl":"https://doi.org/10.1002/prop.70130","url":null,"abstract":"<div>\u0000 \u0000 <p>The addition of Kounterterms to Einstein gravity leads to a finite action for asymptotically anti-de Sitter (AdS) spaces with a conformally flat boundary. In that sense, it provides a partial renormalization for AdS gravity when compared to standard holographic techniques, where the mismatch is given in terms of nontrivial conformal properties of the boundary. On the other hand, this method has the clear advantage that the variation of the action has a closed form in an arbitrary dimension. In this work, it is shown how to extract holographic information on conformal anomalies from the variation in <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <mn>2</mn>\u0000 <mi>n</mi>\u0000 <mo>+</mo>\u0000 <mn>1</mn>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 <annotation>$(2n+1)$</annotation>\u0000 </semantics></math>-dimensional Einstein-AdS plus Kounterterms. Remarkably enough, a considerable part of the Weyl anomaly can be worked out for any odd dimension.</p></div>","PeriodicalId":55150,"journal":{"name":"Fortschritte Der Physik-Progress of Physics","volume":"74 7","pages":""},"PeriodicalIF":5.4,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148386224","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}

{"title":"Issue Information: Fortschritte der Physik 7 / 2026","authors":"","doi":"10.1002/prop.70131","DOIUrl":"https://doi.org/10.1002/prop.70131","url":null,"abstract":"","PeriodicalId":55150,"journal":{"name":"Fortschritte Der Physik-Progress of Physics","volume":"74 7","pages":""},"PeriodicalIF":5.4,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/prop.70131","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148386223","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Approximate Ricci-Flat Metrics for Calabi–Yau Manifolds","authors":"Seung-Joo Lee,&nbsp;Andre Lukas","doi":"10.1002/prop.70129","DOIUrl":"https://doi.org/10.1002/prop.70129","url":null,"abstract":"<p>We outline a method to determine analytic Kähler potentials with associated approximately Ricci-flat Kähler metrics on Calabi–Yau manifolds. Key ingredients are numerically calculating Ricci-flat Kähler potentials via machine learning techniques and fitting the numerical results to Donaldson's ansatz. We apply this method to the Dwork family of quintic hypersurfaces in <span></span><math>\u0000 <semantics>\u0000 <msup>\u0000 <mi>P</mi>\u0000 <mn>4</mn>\u0000 </msup>\u0000 <annotation>$mathbb {P}^4$</annotation>\u0000 </semantics></math> and an analogous one-parameter family of bi-cubic CY hypersurfaces in <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msup>\u0000 <mi>P</mi>\u0000 <mn>2</mn>\u0000 </msup>\u0000 <mo>×</mo>\u0000 <msup>\u0000 <mi>P</mi>\u0000 <mn>2</mn>\u0000 </msup>\u0000 </mrow>\u0000 <annotation>$mathbb {P}^2times mathbb {P}^2$</annotation>\u0000 </semantics></math>. In each case, a relatively simple analytic expression is obtained for the approximately Ricci-flat Kähler potentials, including the explicit dependence on the complex structure parameter. We find that these Kähler potentials only depend on the modulus of the complex structure parameter.</p>","PeriodicalId":55150,"journal":{"name":"Fortschritte Der Physik-Progress of Physics","volume":"74 7","pages":""},"PeriodicalIF":5.4,"publicationDate":"2026-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/prop.70129","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148358258","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Counting Degrees of Freedom: A Method Applicable From Scalars to \u0000 \u0000 \u0000 f\u0000 (\u0000 Q\u0000 )\u0000 \u0000 $f(mathbb {Q})$\u0000 Gravity and Beyond","authors":"Lavinia Heisenberg","doi":"10.1002/prop.70126","DOIUrl":"https://doi.org/10.1002/prop.70126","url":null,"abstract":"<p>We present a clear, step-by-step method for counting degrees of freedom and identifying constraints in general field theories. This approach, grounded in the works of Einstein, Hilbert, Cartan, Kuranishi, and, more recently, Seiler, is neither Lagrangian nor Hamiltonian in nature. Instead, it applies directly to the field equations. We offer a transparent physical interpretation of the method, establish new results, and explore a broad set of examples to demonstrate its power and generality. Notably, we apply the method to <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>f</mi>\u0000 <mo>(</mo>\u0000 <mi>Q</mi>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 <annotation>$f(mathbb {Q})$</annotation>\u0000 </semantics></math> gravity, where traditional techniques such as the Dirac–Bergmann algorithm are ineffective, and obtain seven propagating degrees of freedom.</p>","PeriodicalId":55150,"journal":{"name":"Fortschritte Der Physik-Progress of Physics","volume":"74 6","pages":""},"PeriodicalIF":5.4,"publicationDate":"2026-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/prop.70126","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148325007","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}