The European Physical Journal C最新文献

{"title":"Warm inflation in a braneworld scenario","authors":"Sabina Yeasmin,&nbsp;Atri Deshamukhya","doi":"10.1140/epjc/s10052-026-16156-3","DOIUrl":"10.1140/epjc/s10052-026-16156-3","url":null,"abstract":"<div><p>In the literature, many warm inflationary models are formulated. In this piece of work, a warm inflationary model in the braneworld scenario is studied, considering constant and variable dissipation coefficients. Performance of the model has been considered in both strong and weak dissipative regimes. We study the dynamics of this scenario under slow-roll approximation and estimate cosmological observables, viz., the spectral index and tensor-to-scalar ratio. In order to constrain the parameters in our model, we consider data from Planck 2018 and BICEP.\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"86 8","pages":""},"PeriodicalIF":4.9,"publicationDate":"2026-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-026-16156-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148838380","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":"Exact black hole solutions with semi-symmetric vectorial torsion","authors":"Lehel Csillag,&nbsp;Tiberiu Harko","doi":"10.1140/epjc/s10052-026-16189-8","DOIUrl":"10.1140/epjc/s10052-026-16189-8","url":null,"abstract":"<div><p>Semi-Symmetric Metric Gravity extends general relativity by introducing a semi-symmetric connection with vectorial torsion. The modified field equations contain extra contributions from the torsion vector and its derivatives. Assuming a purely radial torsion vector consistent with spherical symmetry, we derive two exact vacuum solutions. The metric depends on two integration constants, defining the Schwarzschild radius and a new cosmological-type length scale. Classical Solar System tests, including perihelion precession, light deflection, and radar echo delay, are used to constrain the new length scale and the associated deviations from general relativity. The thermodynamic properties of the resulting black hole solutions are investigated, and it is shown that the vector perturbation sector is linearly stable.\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"86 8","pages":""},"PeriodicalIF":4.9,"publicationDate":"2026-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-026-16189-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148838381","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":"MoCaNLO: a Monte Carlo integrator for NLO calculations","authors":"A. Denner,&nbsp;D. Lombardi,&nbsp;S. Lopez Portillo Chavez,&nbsp;M. Pellen,&nbsp;G. Pelliccioli","doi":"10.1140/epjc/s10052-026-15752-7","DOIUrl":"10.1140/epjc/s10052-026-15752-7","url":null,"abstract":"<div><p>We present the Monte Carlo integration code MoCaNLO, which computes cross sections and distributions for processes at high-energy colliders like the LHC at leading and next-to-leading order (NLO) in the strong and electroweak couplings. It relies on the <span>Recola</span> package for the calculation of matrix elements and uses Catani–Seymour dipole subtraction for the treatment of infrared singularities. It has been used for several cutting-edge calculations of NLO QCD and electroweak corrections over the last years, such as NLO QCD corrections to off-shell top–antitop-quark production in association with a pair of bottom quarks and NLO electroweak corrections to vector-boson scattering processes.\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"86 8","pages":""},"PeriodicalIF":4.9,"publicationDate":"2026-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-026-15752-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148838176","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":"Krylov complexity for (eta ) deformed superstring backgrounds","authors":"Dibakar Roychowdhury","doi":"10.1140/epjc/s10052-026-16265-z","DOIUrl":"10.1140/epjc/s10052-026-16265-z","url":null,"abstract":"<div><p>We compute the holographic Krylov complexity for a class of strongly coupled Quantum Field Theory (QFT) (with broken scale invariance) in a top down approach, where the dual gravitational counterpart corresponds to <span>(eta )</span> deformed superstring solutions in a type IIB set up. The full 10d solution contains the anti-de Sitter (<i>AdS</i>) as the subspace, along with the dilaton and the background Ramond–Ramond (RR) and Neveu–Schwarz (NS) fluxes. The Krylov complexity in the dual operator picture is obtained by computing the proper momentum of the massive particle along its geodesic in the bulk spacetime. We explore the effects of <span>(eta )</span> deformation on the bulk momentum of the particle, which in turn affects the rate of growth of complexity in the dual QFTs. Our results boil down into the undeformed case in the appropriate limit of the Yang–Baxter (YB) parameter. We also comment on the complexity of the dual quantum mechanical model with broken scale invariance.\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"86 8","pages":""},"PeriodicalIF":4.9,"publicationDate":"2026-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-026-16265-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148837545","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":"Can UV meet IR in the Swiss cheese?","authors":"Madina Abilmazhinova,&nbsp;Diana Kulubayeva,&nbsp;Hrishikesh Chakrabarty,&nbsp;Daniele Malafarina","doi":"10.1140/epjc/s10052-026-16274-y","DOIUrl":"10.1140/epjc/s10052-026-16274-y","url":null,"abstract":"<div><p>We consider the embedding of regular black holes in an expanding universe and study how the ultraviolet modifications to the Schwarzschild geometry that regularize the black hole singularity affect the exterior universe’s expansion rate. We consider several proposals for the regular black hole geometry and obtain the corresponding Friedmann equations for a universe filled only with dust and black holes. We show that different proposals have different implications which may be distinguished. We then test the hypothesis that the UV corrections to the black hole geometry may be responsible for the current phase of accelerated expansion. To this aim we constrain the value of the regular black hole UV cutoff parameter from observations. Interestingly we find that the best fit is obtained by values of the parameter corresponding to regular horizonless compact objects.\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"86 8","pages":""},"PeriodicalIF":4.9,"publicationDate":"2026-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-026-16274-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148837544","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":"An (A_4) model to accommodate maximal (theta _{23}) and maximal (delta ) consistent with (mu )–(tau ) reflection symmetry","authors":"Rupak Chakrabarty,&nbsp;Chandan Duarah","doi":"10.1140/epjc/s10052-026-16236-4","DOIUrl":"10.1140/epjc/s10052-026-16236-4","url":null,"abstract":"<div><p>In this work, we construct an <span>(A_4)</span>-based flavor symmetry model within the framework of the type-I seesaw mechanism to realize a light neutrino mass matrix consistent with <span>(mu )</span>–<span>(tau )</span> reflection symmetry. The entire framework is based on the Standard Model gauge symmetry extended by the discrete group <span>(A_4 times Z_2 times Z_4)</span>. In general, the elements of the light Majorana neutrino mass matrix are complex. The <span>(mu )</span>–<span>(tau )</span> reflection symmetric texture of the mass matrix can be realized in a generalized CP symmetry limit. In this symmetry limit, the model predicts a maximal atmospheric mixing angle <span>(theta _{23} = pi /4)</span> and a maximal Dirac CP phase <span>(delta = (pi /2) / (3pi /2))</span>. These features are consistent with current experimental observations, including a near-maximal value of <span>(theta _{23})</span>, a non-zero <span>(theta _{13})</span>, and a preference for <span>(delta )</span> close to <span>(270^circ )</span>, as indicated by the T2K and NO<span>(nu )</span>A experiments. Non-maximal values of <span>(theta _{23})</span> and <span>(delta )</span> can be accommodated when one does not restrict to the CP symmetry limit. The model predictions for the mixing angles and the Dirac CP phase <span>(delta )</span> are then controlled by two model parameters. We perform a numerical analysis to identify the allowed model parameter values consistent with current global <span>(3nu )</span> oscillation data. The model successfully reproduces the observed deviations of <span>(theta _{23})</span> and <span>(delta )</span> from their maximal values, while accommodating the observed values of <span>(theta _{12})</span> and <span>(theta _{13})</span>, consistent with current global fit data. We also study the charged lepton flavor violating decays <span>(mu rightarrow egamma )</span> and <span>(mu rightarrow 3e)</span>, whose predicted branching ratios satisfy current experimental bounds.</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"86 8","pages":""},"PeriodicalIF":4.9,"publicationDate":"2026-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-026-16236-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148838082","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":"Effects of the ekpyrotic mechanism on inflationary phase in loop quantum cosmologies","authors":"Christian Brown,&nbsp;Jared Fier,&nbsp;Brian Phillips,&nbsp;Gerald Cleaver,&nbsp;Anzhong Wang","doi":"10.1140/epjc/s10052-026-16275-x","DOIUrl":"10.1140/epjc/s10052-026-16275-x","url":null,"abstract":"<div><p>In bouncing cosmological models – whether classical or quantum – the big bang singularity is replaced by a regular bounce. A well-known challenge is controlling the growth of shear during the contracting phase, as the shear scales as <span>(a^{-6})</span> toward the bounce, where <i>a</i> is the average expansion factor of the universe. A common solution is to introduce a scalar field with an ekpyrotic-like potential that becomes negative near the bounce, giving an effective equation of state greater than one, thereby dominating the shear and allowing a homogeneous, isotropic universe to emerge after the bounce. In this paper, we investigate how the ekpyrotic mechanism affects the inflationary phase in both loop quantum cosmology (LQC) and a modified loop quantum cosmology model (mLQC-I) – frameworks in which inflation is otherwise generic. We consider a potential consisting of an inflationary part and an ekpyrotic-like component. Through numerical studies of various models, we find that the ekpyrotic mechanism can significantly influence the subsequent inflation, even though, for appropriately chosen parameters, it dominates near the bounce (with equation of state <span>(w &gt; 1)</span>) and successfully resolves the shear problem. As time increases beyond the bounce, the inflationary potential eventually dominates, producing an inflationary phase that can be long enough to address standard hot big bang cosmology problems. Nevertheless, our numerical findings suggest that fine-tuning may be required. Because the results are numerical, our conclusions are not definitive, and a more systematic analysis will be necessary to fully assess the generality of the observed behavior.\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"86 8","pages":""},"PeriodicalIF":4.9,"publicationDate":"2026-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-026-16275-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148838080","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":"Twist-3 transverse momentum dependent gluon distributions in a spectator model","authors":"Xiupeng Xie,&nbsp;Zhun Lu","doi":"10.1140/epjc/s10052-026-16209-7","DOIUrl":"10.1140/epjc/s10052-026-16209-7","url":null,"abstract":"<div><p>We study the twist-3 transverse momentum dependent distributions of gluons in a nucleon within a spectator model framework. In this model, the nucleon is described as emitting a virtual (time-like) gluon and an on-shell spectator particle, with the spectator mass treated continuously via a spectral function. The twist-3 gluon-gluon correlators, <span>(Phi ^{+i;+-})</span> and <span>(Phi ^{ij;l+})</span>, are parameterized by a set of complex functions, whose real and imaginary parts correspond to T-even and T-odd components, respectively. We numerically check the equation of motion relation for these distributions and find that relation holds fairly well in the spectator model. \u0000\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"86 8","pages":""},"PeriodicalIF":4.9,"publicationDate":"2026-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-026-16209-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148837463","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":"Circular-orbit dynamics and QPO constraints in static Einstein–scalar–Gauss–Bonnet black holes","authors":"Sardor Murodov,&nbsp;Bekzod Rahmatov,&nbsp;Otabek Umarov,&nbsp;Anvar Kurbaniyazov,&nbsp;Faisal Javed,&nbsp;Javlon Rayimbaev","doi":"10.1140/epjc/s10052-026-16256-0","DOIUrl":"10.1140/epjc/s10052-026-16256-0","url":null,"abstract":"<div><p>Einstein–scalar–Gauss–Bonnet (EsGB) gravity provides a physically motivated framework for testing strong-field deviations from the Schwarzschild geometry through scalar hair. We study neutral-particle circular motion and high-frequency quasi-periodic oscillations (HF-QPOs) in static EsGB black holes described by a continued-fraction metric with a single dimensionless deformation parameter <span>(p)</span> on the Schwarzschild-connected quadratic-coupling branch. We determine the effective potential, circular-orbit energy and angular momentum, characteristic radii, and orbital and radial epicyclic frequencies, and apply the relativistic precession model to twin-peak QPO data from XTE J1550–564, GRO J1655–40, GRS 1915+105, and M82 X-1. A source-by-source Markov chain Monte Carlo (MCMC) analysis shows that the observed frequency pairs can be reproduced within their uncertainties and that the radial epicyclic frequency carries the main model-level sensitivity to <span>(p)</span>. However, a controlled prior-sensitivity analysis using uniform and truncated Gaussian priors finds that the marginal posterior of <span>(p)</span> closely follows the adopted prior for all four sources. This reflects the intrinsic underconstraint of fitting three correlated parameters <span>((M,p,r))</span> to two measured frequencies. The inferred intervals therefore represent model-dependent compatibility regions rather than an independent measurement or preferred value of the EsGB deformation. The static results provide a baseline for future rotating and multi-observable tests.\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"86 8","pages":""},"PeriodicalIF":4.9,"publicationDate":"2026-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-026-16256-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148838083","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":"Phase diagram of chiral 2-flavor QCD based on an effective approach","authors":"Edgar López-Contreras,&nbsp;José Antonio García-Hernández,&nbsp;Elías Natanael Polanco-Euán,&nbsp;Wolfgang Bietenholz","doi":"10.1140/epjc/s10052-026-16229-3","DOIUrl":"10.1140/epjc/s10052-026-16229-3","url":null,"abstract":"<div><p>Despite intense experimental and theoretical research, the QCD phase diagram at finite baryon density remains to a large extent unexplored. From the theoretical side, the obvious non-perturbative approach is lattice QCD simulations, which are, however, obstructed by a severe sign problem. Here we employ the O(4) non-linear <span>(sigma )</span>-model as an effective theory for 2-flavor QCD in the chiral limit. The identical pattern of spontaneous symmetry breaking indicates that they belong to the same universality class. We assume high temperature dimensional reduction to the 3d O(4) model, with topological charge taking the role of the baryon number, along the lines of Skyrme’s model. In this effective formulation, the baryonic chemical potential <span>(mu _{B})</span> can be included in the lattice formulation without causing any sign problem in Monte Carlo simulations. This allows us to pin down the critical line, i.e. the critical temperature <span>(T_textrm{c}(mu _{B}),)</span> which decreases monotonically for increasing <span>(mu _{B}.)</span> In the range <span>(0 &lt; mu _{B} lesssim 309~textrm{MeV})</span> and <span>(132~textrm{MeV} gtrsim T_textrm{c} gtrsim 107~textrm{MeV},)</span> we do not find a Critical Endpoint (CEP), although there are hints for it to be in the vicinity of the maximal <span>(mu _{B})</span>-value that we could explore.\u0000</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/s10052-026-16229-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148837732","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}