The European Physical Journal C最新文献

{"title":"Dyonic Kerr–Sen black hole’s resonant scattering: absorption and superradiance","authors":"Supakorn Katewongveerachart,&nbsp;David Senjaya","doi":"10.1140/epjc/s10052-026-15717-w","DOIUrl":"10.1140/epjc/s10052-026-15717-w","url":null,"abstract":"<div><p>We analytically investigate scalar superradiant scattering in the rotating dyonic Kerr–Sen black hole of Einstein–Maxwell-dilaton–axion theory. Starting from the separable Klein–Gordon equation for a massive neutral scalar field, we work in the low-frequency and slow-rotation regime and employ the analytical asymptotic matching (AAM) method to compute the reflection coefficient and the associated superradiant amplification factor. Since an exact global scattering solution is not available in this four-charge geometry, the AAM framework enables a controlled analytic treatment of the near-and far-region dynamics. We provide detailed and systematic derivations of the matching procedure leading to the closed-form amplification formula. The superradiant condition is obtained explicitly and we demonstrate that energy extraction occurs exclusively for co-rotating modes satisfying <span>(Omega &lt; m Omega _H)</span>. We show that the presence of electric and magnetic charges suppresses the amplification relative to the Kerr limit, whereas lighter co-rotating scalar fields broaden the superradiant window and enhance the efficiency of rotational energy extraction.\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"86 5","pages":""},"PeriodicalIF":4.8,"publicationDate":"2026-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-026-15717-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147829132","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":"Non-minimal effective scalar–tensor gravity in the early universe","authors":"Oleg Zenin,&nbsp;Roman Stamov,&nbsp;Sergey Kuzmin,&nbsp;Stanislav Alexeyev","doi":"10.1140/epjc/s10052-026-15585-4","DOIUrl":"10.1140/epjc/s10052-026-15585-4","url":null,"abstract":"<div><p>We study the consistency of several early-Universe scenarios within a framework of non-minimal effective scalar–tensor gravity. We show that bounce, inflation, and genesis stages are supported within the aforementioned theory. Consequently, this framework can serve as a viable model of the early Universe, where accelerated expansion is driven by the theory’s own intrinsic degrees of freedom. Notably, the theory also provides two different values of the Hubble parameter, potentially explaining the different values of the Hubble constant measured from galaxy clusters and relic radiation, respectively.\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"86 5","pages":""},"PeriodicalIF":4.8,"publicationDate":"2026-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-026-15585-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147829381","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":"Strong CP and the QCD axion lecture notes via effective field theory","authors":"Francesco Sannino","doi":"10.1140/epjc/s10052-026-15612-4","DOIUrl":"10.1140/epjc/s10052-026-15612-4","url":null,"abstract":"<div><p>These lecture notes provide a self-contained, graduate-level introduction to the strong <i>CP</i> problem and QCD axion physics from an effective field theory (EFT) viewpoint. We review the construction of the chiral EFT of QCD yielding a <span>(theta )</span>-dependent potential, from which vacuum alignment, <span>(theta )</span> periodicity and branch structure follow. We further show how the framework leads to the Witten–Veneziano relation highlighting the role of the pure-glue topological susceptibility in organizing <span>(theta )</span>-dependent hadronic observables. Using these tools, we show how to extract representative <i>CP</i>-odd mesonic and baryonic amplitudes, including the chiral estimate underlying the neutron EDM bound, and how to generalize the effective framework to confining <span>(operatorname {SU}(N))</span> theories with fermions in arbitrary representations. We further show how to employ the Veneziano–Yankielowicz effective Lagrangian for <span>(mathcal {N}=1)</span> supersymmetric Yang–Mills theory to extract salient information on the <span>(theta )</span>-dependent physics of one-flavour QCD via orientifold planar equivalence. We also revisit a recent no strong <i>CP</i> claim based on an ordering of limits in the sum over topological sectors and show, in the EFT language, that it amounts to introducing an extra non-propagating axion-like degree of freedom not required by QCD. We then present the standard dynamical resolution to the strong <i>CP</i> problem, i.e. the Peccei–Quinn mechanism, the resulting axion potential and mass from chiral EFT and briefly review associated time-honored UV completions, and the axion quality problem from gravitational corrections.\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"86 5","pages":""},"PeriodicalIF":4.8,"publicationDate":"2026-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-026-15612-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147829194","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":"Quantum corrections to the AdS bulk from a semiclassical description of D-branes","authors":"Andrei T. Patrascu","doi":"10.1140/epjc/s10052-026-15724-x","DOIUrl":"10.1140/epjc/s10052-026-15724-x","url":null,"abstract":"<div><p>We investigate the emergence of spacetime geometry within the AdS/CFT correspondence by explicitly incorporating quantum coherence effects arising from finite coherent superpositions of closed-string modes forming mesoscopic quantum D-branes. We show that the stage at which quantum coherence is suppressed relative to the construction of the emergent geometry significantly influences the resulting spacetime structure. Suppressing coherence prior to constructing the effective geometric description yields a purely classical Anti-de Sitter (AdS) geometry, whereas constructing the geometry from a coherent state and only subsequently suppressing interference leads to controlled quantum corrections of order <span>(O(M^{-2}))</span> to the AdS background. We further demonstrate that both microscopic coherence between string modes and mesoscopic coherence among D-branes distinctly shape the resulting spacetime structure, introducing measurable quantum deviations from classical geometry. Our results provide critical insights into how quantum coherence may underpin the emergence of classical gravity and offer new directions for studying quantum-gravitational phenomena within holographic frameworks.\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"86 5","pages":""},"PeriodicalIF":4.8,"publicationDate":"2026-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-026-15724-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147829532","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":"Back-reaction effects of matter accretion onto a modified Schwarzschild black hole","authors":"Afeefa Bibi,&nbsp;M. Z. A. Moughal","doi":"10.1140/epjc/s10052-026-15716-x","DOIUrl":"10.1140/epjc/s10052-026-15716-x","url":null,"abstract":"<div><p>This work analytically investigates the back-reaction of accreting matter onto a modified Schwarzschild black hole within a perturbative framework, assuming quasi-steady accretion. To address different physical scenarios, three accretion models dust, radiative and perfect fluid are examined, and systematic corrections to the metric coefficients are derived. From these corrections, explicit forms of the mass function are obtained, from which the corrected apparent horizon is determined. The thermodynamic properties of the system are also explored in light of these modifications. Our results show that, independent of the chosen energy-momentum tensor, the near-horizon behavior of the corrected geometry consistently reduces to the Vaidya form. This establishes the universality of the perturbative method in the context of modified Schwarzschild black holes and provides new insights into the interplay between accretion dynamics, horizon structure, and BH thermodynamics. We also compare the results for the Schwarzschild black hole, the perturbed Schwarzschild black hole, and the modified Schwarzschild black hole, and find that the modified Schwarzschild black hole exhibits stronger back-reaction effects than the others.\u0000\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"86 5","pages":""},"PeriodicalIF":4.8,"publicationDate":"2026-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-026-15716-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147829528","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":"Pseudo-Newtonian potential for accretion disks in a modified gravity spacetime around the black hole and underlying properties","authors":"Sriraj Chandra,&nbsp;Banibrata Mukhopadhyay","doi":"10.1140/epjc/s10052-026-15701-4","DOIUrl":"10.1140/epjc/s10052-026-15701-4","url":null,"abstract":"<div><p>We construct a pseudo-Newtonian potential (PNP) corresponding to a rotating black hole solution in a modified gravity (MGR) framework using a metric-based prescription. The motivation is to enable realistic accretion disk studies in MGR, where full relativistic MHD simulations remain computationally prohibitive. Effective potentials and the underlying Newtonian-like forces are derived for both massive and massless particles in the equatorial plane, relevant for disk dynamics. The reliability of the PNP is tested by comparing key orbital properties – marginally stable, marginally bound, photon orbits and energies at marginally stable orbit radii – with exact MGR predictions. The PNP reproduces the marginally stable and photon orbits exactly, while marginally bound orbits and specific energies deviate by less than about 7–10%. The influence of the MGR parameter on particle dynamics and effective potentials is analyzed, revealing non-trivial departures from simple Newtonian intuition. The study demonstrates that the proposed PNP accurately captures essential spatial properties of MGR spacetime and provides an efficient, physically consistent tool for investigating accretion phenomena and strong-gravity astrophysics beyond general relativity.\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"86 5","pages":""},"PeriodicalIF":4.8,"publicationDate":"2026-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-026-15701-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147829275","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":"Polarized radiative transfer of Kerr–Newman black hole","authors":"Xin Li,&nbsp;Sen Guo,&nbsp;Pei Wang,&nbsp;En-Wei Liang,&nbsp;Huan Deng,&nbsp;Yu Liang,&nbsp;Xiao-Xiong Zeng,&nbsp;Kai Lin,&nbsp;Qing-Quan Jiang","doi":"10.1140/epjc/s10052-026-15683-3","DOIUrl":"10.1140/epjc/s10052-026-15683-3","url":null,"abstract":"<div><p>In this analysis, we investigate the polarization radiation imaging of Kerr–Newman black holes, with a particular focus on the impact of black hole charge on photon propagation and polarization characteristics. By extending the traditional Walker–Penrose method, which is limited by its reliance on specific symmetric structures and Killing tensors, we overcome these limitations by constructing an ordinary differential equations (ODEs) numerical framework that combines the photon orbit equation with the polarization parallel transport equation. This allows for the self-consistent evolution of photon trajectories and polarization states in any spacetime backgrounds without relying on specific symmetries. Using this framework, we analyze the effects of black hole spin and charge on the polarization characteristics of radiation from both prograde and retrograde accretion disks. Our results show that black hole charge can significantly modify photon trajectories and polarization patterns: increasing charge compresses and distorts the EVPA structure on photon-ring scales, inducing localized rotations and asymmetries that may provide a potential diagnostic of a nonzero black hole charge.\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"86 5","pages":""},"PeriodicalIF":4.8,"publicationDate":"2026-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-026-15683-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147829613","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":"The angular observables of (Lambda _b rightarrow Lambda _c(rightarrow Lambda ^0 pi ^+) , tau ^-(rightarrow pi ^- nu _tau ), {bar{nu }}_tau ) within the paradigm of FCCC anomalies","authors":"Muhammad Arslan,&nbsp;Ishtiaq Ahmed,&nbsp;Muhammad Jamil Aslam","doi":"10.1140/epjc/s10052-026-15601-7","DOIUrl":"10.1140/epjc/s10052-026-15601-7","url":null,"abstract":"<div><p>We present a global analysis of the current <i>B</i>-meson flavor anomalies and extend it to the baryonic sector through the decay <span>(Lambda _b^0 rightarrow Lambda _c^+(rightarrow Lambda ^0 pi ^+) tau ^-(rightarrow pi ^- nu _tau ){bar{nu }}_tau )</span>. The lepton flavor universality ratios <span>(R_{tau /(mu ,e)}(D^{(*)}))</span>, measured by BaBar, Belle, and LHCb, exhibit a combined <span>(3.8sigma )</span> deviation from Standard Model (SM) predictions. Using the latest HFLAV averages and imposing <span>(B_c)</span>-lifetime constraints on the branching ratio, <span>({mathcal {B}}(B_c rightarrow tau nu ) &lt; 60%, 30%, 10%)</span>, we perform a global fit to the anomaly data and propagate the preferred new physics (NP) solutions to the full cascade decay <span>(Lambda _b^0 rightarrow Lambda _c^+(rightarrow Lambda ^0 pi ^+) tau ^-(rightarrow pi ^- nu _tau ){bar{nu }}_tau )</span>. The mixed vector-scalar scenario <span>((C_{V_L},C_{S_R}))</span> emerges as the most favored NP solution, yielding the largest pull from the SM while remaining insensitive to branching-ratio constraints. The single-operator <span>(C_{V_L})</span> case identified as the next most competitive scenario. We study the impact of NP vector, scalar and tensor operators on a complete set of angular observables on the five-fold <span>(Lambda _b)</span> decay using Lattice-QCD form factors and find that the scenarios <span>((Re [C_{S_L}=4C_T],Im [C_{S_L}=4C_T]))</span> and <span>((C_{S_L},C_{S_R}))</span> generate the largest deviations from the SM predictions. In particular, the observables <span>({mathcal {K}}_{1c})</span>, <span>({mathcal {K}}_{2ss})</span>, <span>({mathcal {K}}_{2cc})</span>, and <span>({mathcal {K}}_{4s})</span> show the highest sensitivity to NP effects. The correlation analysis reveals distinctive NP patterns: the <span>((Re [C_{S_L}=4C_T],Im [C_{S_L}=4C_T]))</span> scenario exhibits inverse correlations among <span>({mathcal {K}}_{1c})</span> and <span>({mathcal {K}}_{2ss,2cc,4s})</span> and direct correlations between <span>({mathcal {K}}_{2ss})</span> and <span>({mathcal {K}}_{2cc,4s})</span>, pointing to destructive helicity interference and a possible CP-violating phase, while the <span>((C_{S_L},C_{S_R}))</span> scenario displays complementary behavior consistent with CP-conserving dynamics. These results establish baryonic semileptonic decays as a powerful and independent probe of the <span>(R_{tau /(mu ,e)}(D^{(*)}))</span> anomalies, with future measurements providing critical tests of the underlying NP structure.\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"86 5","pages":""},"PeriodicalIF":4.8,"publicationDate":"2026-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-026-15601-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147829533","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":"Acceleration radiation of a two-level atom freely falling into a nonsingular black hole with holonomy corrections","authors":"Ar Rohim,&nbsp;Anto Sulaksono","doi":"10.1140/epjc/s10052-026-15660-w","DOIUrl":"10.1140/epjc/s10052-026-15660-w","url":null,"abstract":"<div><p>In this study, we examine a two-level atom freely falling into an effective model of a static, spherically symmetric, nonsingular black hole with holonomy corrections. The quantum correction parameter produces black hole remnants as the size approaches the horizon. In the system, the atom interacts with a massless scalar photon through a Boulware-like vacuum. We discuss how quantum corrections affect the form of the atom’s excitation and absorption probabilities. We find that the excitation probability decreases with increasing quantum correction parameter, whereas the absorption probability increases. We confirm that the Einstein equivalence principle holds for such a system, as expected. We also examined the behavior of the modified horizon brightened acceleration radiation under holonomy corrections. We recover the standard Hawking temperature and Hawking–Bekeinstein entropy when holonomy corrections vanish.\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"86 5","pages":""},"PeriodicalIF":4.8,"publicationDate":"2026-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-026-15660-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147829621","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":"Periodic orbits and gravitational radiation from extreme mass-ratio inspirals as probes of black hole quantum hair","authors":"Yiru Zhang,&nbsp;Meirong Tang,&nbsp;Zhaoyi Xu","doi":"10.1140/epjc/s10052-026-15715-y","DOIUrl":"10.1140/epjc/s10052-026-15715-y","url":null,"abstract":"<div><p>The classical no-hair theorem states that stationary black holes in general relativity can be completely described by only a small set of global parameters. Within this framework, no additional geometric structures are expected to persist outside the event horizon. However, quantum vacuum polarization may introduce small modifications to the near-horizon geometry, effectively giving rise to what is known as quantum hair. Such corrections may provide a possible window into the microscopic structure and thermodynamic properties of black holes. In this work, we examine how the quantum hair parameter <span>(gamma )</span> influences the periodic orbital dynamics of test bodies in extreme mass-ratio inspirals (EMRIs) and their associated gravitational-wave emission. We find that <span>(gamma )</span> significantly modifies the characteristic radii and angular momenta of two important circular orbits, namely the marginally bound orbit (MBO) and the innermost stable circular orbit (ISCO), leading to a shift in the allowed region of the energy–angular momentum (<i>E</i>–<i>L</i>) phase space. Based on the rational number <i>q</i> classification, we further show that quantum corrections tend to enhance the zoom–whirl orbital behavior. Within the conservative Numerical Kludge framework adopted in this work, the quantum hair parameter modifies the effective potential and induces small shifts in the fundamental orbital frequencies, which in turn produce cumulative phase differences in long-duration waveform evolutions. These results provide an illustrative example of how quantum-corrected geometry can affect conservative orbital dynamics and waveform phasing, and they offer a phenomenological basis for future, more complete studies of possible quantum-gravity imprints in EMRI signals.\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"86 5","pages":""},"PeriodicalIF":4.8,"publicationDate":"2026-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-026-15715-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147829531","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}