The European Physical Journal C最新文献

{"title":"Symmetric tensor coupling in holographic mean-field theory: deformed Dirac cones","authors":"Moongul Byun,&nbsp;Taewon Yuk,&nbsp;Sang-Jin Sin","doi":"10.1140/epjc/s10052-026-16244-4","DOIUrl":"10.1140/epjc/s10052-026-16244-4","url":null,"abstract":"<div><p>We extend the holographic mean-field theory to rank-two symmetric tensor field as an external source coupled with fermion. We classify the roles of symmetric tensor coupling according to the effect on the spectral density: cone-angle change, squashing, and tilting of the spectral light cones. The over-tilted light cone is also achieved in a generalized prescription, which consistently retains the causality condition. Our results provide agreements between the holographic spectra with those observed in real materials, such as type-II Dirac cones and strained graphene.</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"86 8","pages":""},"PeriodicalIF":4.9,"publicationDate":"2026-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-026-16244-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148837733","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Finite-field QED corrections to vacuum birefringence and magnetar polarization transport","authors":"Shahram Abbassi,&nbsp;F. A. Chishtie,&nbsp;S. R. Valluri","doi":"10.1140/epjc/s10052-026-16246-2","DOIUrl":"10.1140/epjc/s10052-026-16246-2","url":null,"abstract":"<div><p>We study low-energy photon propagation in a constant magnetic field within the finite-field one-loop Heisenberg–Euler framework and apply the resulting mode-dependent refractive indices to magnetar polarization transport. In a centered-dipole model, the polarization-limiting radius is unchanged to better than <span>(10^{-12})</span> because mode decoupling occurs at <span>(sim 10^2R_textrm{NS})</span>, where <span>(Bll B_textrm{cr})</span>. Near the surface, however, the weak-field Cotton–Mouton expression overestimates the accumulated birefringent phase by up to a factor 2.9 at <span>(10^{15})</span> G. At the plasma–vacuum resonance, finite-field corrections reduce the resonance density by <span>(32%)</span> and raise the adiabatic conversion energy by <span>(14%)</span> for 1E 1547.0-5408; the corresponding changes are factors 2.6 and 1.37 for 1RXS J1708-4009, and factors 9.7 and 2.13 for SGR 1806-20, the latter controlled by the strong-field asymptote. The parallel-mode magnetic response remains positive and exhibits a broad maximum near <span>(17B_textrm{cr})</span>. Its strict <span>(mathcal O(alpha ))</span> expansion is monotonic, indicating that the detailed position and profile of the maximum are not controlled beyond the present approximation and require higher-loop assessment. These results identify vacuum-resonance observables as the most sensitive channel for testing finite-field QED in magnetars.\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"86 8","pages":""},"PeriodicalIF":4.9,"publicationDate":"2026-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-026-16246-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148837449","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"White dwarf stars in Randall–Sundrum II braneworld gravity: perturbative bounds on super-chandrasekhar configurations","authors":"M. Zeyauddin","doi":"10.1140/epjc/s10052-026-16252-4","DOIUrl":"10.1140/epjc/s10052-026-16252-4","url":null,"abstract":"<div><p>We investigate the equilibrium structure of white dwarf stars in the Randall–Sundrum II braneworld scenario using the effective brane-TOV formulation, with the stellar matter described by the zero-temperature Chandrasekhar electron-degenerate equation of state at mean molecular weight per electron <span>(mu _e = 2)</span>. Scanning a range of brane tensions and Weyl-fluid closure parameters, we ask whether the braneworld corrections can support the super-Chandrasekhar masses (<span>(sim 2,M_odot )</span>) inferred for some over-luminous Type Ia supernova progenitors. To distinguish brane effects within the perturbative regime from formal extrapolations of the effective four-dimensional equations, we introduce a local, mass-based perturbativity diagnostic that compares the solution including the full Weyl evolution with the quadratic-correction-only solution at the same brane tension and central density. We do not compare against an independent non-perturbative five-dimensional solution – none currently exists in the literature for this configuration – but instead assess the perturbative admissibility of the solutions obtained after adopting the CAM closure. The general-relativistic limit is recovered with a Chandrasekhar mass of <span>(1.425,M_odot )</span>, and within the perturbative-validity regime the maximum white dwarf mass is <span>(simeq 1.50,M_odot )</span> – about <span>(5%)</span> above this value and well below <span>(2,M_odot )</span>. Masses approaching <span>(2,M_odot )</span> arise only where the Weyl contribution is no longer perturbative. We conclude that, within the CAM-closed effective brane formulation and subject to the perturbative-validity criterion adopted here, RS-II braneworld corrections can mildly raise the Chandrasekhar mass scale but do not robustly support physical super-Chandrasekhar white dwarfs.\u0000\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"86 8","pages":""},"PeriodicalIF":4.9,"publicationDate":"2026-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-026-16252-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148837450","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Cryogenic pure CsI as a probe for neutrino electromagnetic interactions","authors":"C. M. Lewis","doi":"10.1140/epjc/s10052-026-16253-3","DOIUrl":"10.1140/epjc/s10052-026-16253-3","url":null,"abstract":"<div><p>Searches for neutrino electromagnetic interactions at reactor sites require an unusual combination of ultra-low thresholds and a stable low-background environment. It is shown here that cryogenic undoped cesium iodide (CsI) naturally satisfies these conditions in a way prior detectors have not. Although suppression of nuclear recoil ionization efficiency at low energies limits the use of this scintillator for coherent elastic neutrino-nucleus scattering, that same property renders the detector effectively blind to those nuclear recoils from MeV-scale reactor antineutrinos. This leaves the low-energy regime free to expose neutrino-electron (<span>({bar{nu }}_{e} -e^{-})</span>) scattering as the dominant observable channel and converts cryogenic CsI into a targeted probe of electromagnetic couplings. This work presents a conceptual design based on pure CsI crystals immersed in an active xenon-doped liquid argon veto evaluated under realistic intrinsic and environmental backgrounds. Under present detector capabilities, order-of-magnitude improvements over current reactor limits on the neutrino magnetic moment and millicharge are achievable. Cryogenic pure CsI therefore offers a distinctive and scalable route to leading studies of <span>({bar{nu }}_{e} -e^{-})</span> physics.\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"86 8","pages":""},"PeriodicalIF":4.9,"publicationDate":"2026-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-026-16253-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148837499","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Numerical study of MRW-type unintegrated double parton distribution functions from non-factorized DPDFs","authors":"R. Kord Valeshabadi,&nbsp;S. Rezaie,&nbsp;K. Azizi","doi":"10.1140/epjc/s10052-026-16264-0","DOIUrl":"10.1140/epjc/s10052-026-16264-0","url":null,"abstract":"<div><p>Double parton scattering provides a sensitive probe of multiparton correlations inside hadrons. In this work we present a numerical study of unintegrated double parton distribution functions constructed from non-factorized collinear DPDFs. As input we use the <span>GS09</span> DPDFs and evolve them to unequal scales with a numerical double DGLAP evolution framework, which is validated through the corresponding momentum and valence-number sum rules. We investigate MRW-inspired prescriptions for generating transverse momentum dependence in the double parton case. In particular, we study the double LO-MRW approach (DLO-MRW) in the perturbative region, the double modified KMRW approach (DMKMRW), the double virtuality ordered MRW (DVO-MRW) model, and a normalization-matched version of the latter. The DMKMRW, DVO-MRW, and matched DVO-MRW prescriptions can be applied directly to the full collinear DPDF, including its nonhomogeneous component, and avoid the piecewise treatment required in the conventional LO-MRW construction. We analyze the normalization, transverse momentum dependence, flavor dependence, and sensitivity to longitudinal DPDF correlations of the resulting distributions. The DMKMRW model is normalization preserving by construction, while the DVO-MRW model shows nontrivial normalization deviations that are removed in the matched version. Non-factorized effects are strongly channel-dependent. In DMKMRW, they enter mainly through longitudinal DPDF correlations, whereas in the LO-MRW and virtuality-ordered models, they also modify the transverse momentum shape. The largest deviations occur near the double parton kinematic boundary and in channels affected by valence-number and quark–antiquark correlations.\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"86 8","pages":""},"PeriodicalIF":4.9,"publicationDate":"2026-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-026-16264-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148837500","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"More on pre-inflationary non Gaussianities","authors":"M. Meo","doi":"10.1140/epjc/s10052-026-16261-3","DOIUrl":"10.1140/epjc/s10052-026-16261-3","url":null,"abstract":"<div><p>I generalize the three-point amplitude of curvature perturbations in the climbing scenario inspired by ten-dimensional non-supersymmetric strings to a broader class of exponential potentials, under some assumptions on the smoothing effects of String Theory that favor a bounce Cosmology. The extension can encompass the <span>(SO(16)times SO(16))</span> model, together with other scenarios related to supersymmetry breaking in String Theory. Above and beyond this scheme, the turning point leaves an exactly calculable imprint on the correlators, which is determined by a residue and points to a narrow <i>e</i>-fold range centered around <span>(N simeq 63)</span>. The <i>e</i>-fold ranges compatible with Planck data move toward lower values of <i>N</i> for milder potentials and toward larger values for steeper ones. I also compute the three-point amplitudes involving graviton modes in the same bounce scenario, showing in detail their lack of peculiar contributions from the turning point.\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"86 8","pages":""},"PeriodicalIF":4.9,"publicationDate":"2026-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-026-16261-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148837575","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Yang–Baxter symmetries of type II supergravity","authors":"Igor Bogatyrev,&nbsp;Edvard T. Musaev,&nbsp;Timophey Petrov","doi":"10.1140/epjc/s10052-026-16262-2","DOIUrl":"10.1140/epjc/s10052-026-16262-2","url":null,"abstract":"<div><p>We provide a complete proof that Yang–Baxter bi-vector deformations are solution generating transformations in Type II supergravity. The proof does not rely on the assumption that the vielbein is invariant under Lie derivative along all Killing vectors entering the bi-vector. We analyse transformation of boundary terms and derive a simple expression for the case, when the boundary does not change its geometrical locus.\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"86 8","pages":""},"PeriodicalIF":4.9,"publicationDate":"2026-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-026-16262-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148837574","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Euler-Heisenberg actions for gauge-axial background vectors","authors":"Lucas Pereira de Souza","doi":"10.1140/epjc/s10052-026-16218-6","DOIUrl":"10.1140/epjc/s10052-026-16218-6","url":null,"abstract":"<div><p>We derive the closed-form one-loop Euler–Heisenberg effective actions for Dirac fermions coupled simultaneously to classical electromagnetic vector and massive pseudo-vector backgrounds within a controlled quasi-static approximation. Through complete diagonalization of the functional Hessian, we systematically delineate the parameter space into distinct sectors characterized by stability properties and spectral structure. We identify subspaces that encompass and extend results from previous studies into a broader class, admitting propagating axial fields as physically viable regimes; strikingly, we note sectors presenting chirality-asymmetric instability. This addresses long-standing questions regarding the well-defined nature, diagonalizability, and stability of these models. From the effective actions, we derive novel nonperturbative pair-production rates for simultaneously propagating electromagnetic and axial vector backgrounds; remarkably, we find pronounced vacuum stabilization compared to previous results. Furthermore, we derive the non-perturbative contributions to the chiral current divergence, which enables dynamical chiral symmetry breaking and show that the electromagnetic coupling induces instanton-like configurations for the axial field, even when it is not a fundamental gauge field. As a proof-of-concept, we analyze a cosmological toy model of baryogenesis driven by an axial vector, providing numerical estimates that support the viability of this hypothesis. Additionally, we outline qualitative predictions for Weyl/Dirac semi-metals and briefly discuss potential applications in related phenomena, such as Quark-Gluon plasma, Electroweak scenarios and the Strong-CP problem.</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"86 8","pages":""},"PeriodicalIF":4.9,"publicationDate":"2026-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-026-16218-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148837770","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Emergent universe scenario in the modified Chaplygin gas: towards an exact solution and observational constraints","authors":"D. Panigrahi,&nbsp;S. Chatterjee,&nbsp;B. C. Paul","doi":"10.1140/epjc/s10052-026-16134-9","DOIUrl":"10.1140/epjc/s10052-026-16134-9","url":null,"abstract":"<div><p>The modified Chaplygin gas (MCG) model is revisited to examine its capability in describing the complete cosmic evolution within a unified framework. The model is found to be consistent with observational constraints, including the cosmic microwave background (CMB) shift parameter, while also supporting standard structure formation alongside late-time cosmic acceleration. Due to the highly nonlinear nature of the governing field equations, exact analytical solutions in cosmic time are generally not attainable. To overcome this, we adopt a first-order approximation, which enables us to obtain an analytical expression for the scale factor and determine the corresponding flip time. The effective equation-of-state parameter evolves from a positive value in the early matter-dominated era to <span>(w_{textrm{eff}} approx -1)</span> at late times, in agreement with observations. In addition, a solution in the phantom regime exhibits an emergent, non-singular behavior, where the universe originates from a finite minimum scale factor and smoothly evolves toward a late-time de Sitter-like phase, approaching the <span>(Lambda )</span>CDM limit. The emergent solution is shown to be geodesically complete and free from curvature singularities, as confirmed by the regular behavior of the Kretschmann scalar. We also perform a CMB analysis for all the considered cases, and in each case the obtained values of <span>(R_{textrm{th}})</span> and <span>(chi ^2_{textrm{CMB}})</span> remain consistent with observations within the <span>(1sigma )</span> confidence level. Furthermore, the combined Hubble-57 and CMB analysis leads to significantly improved constraints on the model parameters. Moreover, the obtained solutions are independently verified using the Raychaudhuri equation, providing a consistency check that further reinforces the robustness of the methodology. Overall, the results demonstrate that the MCG model provides a self-consistent and observationally viable description of cosmic evolution without requiring modifications to general relativity.\u0000\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"86 8","pages":""},"PeriodicalIF":4.9,"publicationDate":"2026-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-026-16134-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148837698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Modular flow of celestial conformal field theory","authors":"Mahdis Ghodrati","doi":"10.1140/epjc/s10052-026-16249-z","DOIUrl":"10.1140/epjc/s10052-026-16249-z","url":null,"abstract":"<div><p>We first review the calculations for the modular flow and the vector flow of <span>(text {CFT}_2)</span>, warped CFTs and Bondi–Metzner–Sachs field theories (BMSFTs), and then we present the vector flows and modular flows in Celestial field theory and Klein CFTs. We also discuss the search for this structure in Lifshitz and other exotic field theories.\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"86 8","pages":""},"PeriodicalIF":4.9,"publicationDate":"2026-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-026-16249-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148837845","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}