The European Physical Journal C最新文献

{"title":"Constraining string cosmology with the gravitational-wave background using the NANOGrav 15-year data set","authors":"Qin Tan,&nbsp;You Wu,&nbsp;Lang Liu","doi":"10.1140/epjc/s10052-025-13998-1","DOIUrl":"10.1140/epjc/s10052-025-13998-1","url":null,"abstract":"<div><p>Multiple pulsar timing array (PTA) collaborations, including the European PTA in partnership with the Indian PTA, the North American Nanohertz Observatory for Gravitational Waves (NANOGrav), the Parkes PTA, and the Chinese PTA have recently reported strong evidence for a signal at nanohertz, potentially the first detection of the stochastic gravitational-wave background (SGWB). We investigate whether the NANOGrav signal is consistent with the SGWB predicted by string cosmology models. By performing Bayesian parameter estimation on the NANOGrav 15-year data set, we constrain the key parameters of a string cosmology model: the frequency <span>(f_s)</span> and the fractional energy density <span>(Omega _textrm{gw}^{s})</span> of gravitational waves at the end of the dilaton-driven stage, and the Hubble parameter <span>(H_r)</span> at the end of the string phase. Our analysis yields constraints of <span>(f_s = 1.2^{+0.6}_{-,0.6}times 10^{-8} textrm{Hz})</span> and <span>(Omega _textrm{gw}^{s} = 2.9^{+5.4}_{-2.3}times 10^{-8})</span>, consistent with theoretical predictions from string cosmology. However, the current NANOGrav data is not sensitive to the <span>(H_r)</span> parameter. We also compare the string cosmology model to a simple power-law model using Bayesian model selection, finding a Bayes factor of 2.2 in favor of the string cosmology model. Future pulsar timing array observations with improved sensitivity and extended frequency coverage will enable tighter constraints on string cosmology parameters.</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"85 3","pages":""},"PeriodicalIF":4.2,"publicationDate":"2025-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-025-13998-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143667866","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":"From the unification of conformal and fuzzy gravities with internal interactions to the SO(10) GUT and the particle physics standard model","authors":"Gregory Patellis,&nbsp;Nicholas Tracas,&nbsp;George Zoupanos","doi":"10.1140/epjc/s10052-025-13938-z","DOIUrl":"10.1140/epjc/s10052-025-13938-z","url":null,"abstract":"<div><p>In the present study, the unification of the Conformal and Fuzzy Gravities with the Internal Interactions is based on the observation that the tangent space of a curved space and the space itself do not have necessarily the same dimensions. Moreover, the construction is based on the fact that the gravitational theories can be formulated in a gauge-theoretical way. In the present work we study the various consecutive breakings through which these unified theories can ultimately result into the Standard Model. We estimate the scales of the breakings in each case using one-loop RGEs.</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"85 3","pages":""},"PeriodicalIF":4.2,"publicationDate":"2025-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-025-13938-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143668344","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":"Elaborating Higgs to dimuon decay from gluon fusion by decorrelation and jet substructure","authors":"Subin Han,&nbsp;Hyung Do Kim","doi":"10.1140/epjc/s10052-025-13988-3","DOIUrl":"10.1140/epjc/s10052-025-13988-3","url":null,"abstract":"<div><p>Discovery of the Higgs boson decay to dimuon is anticipated soon based on the current evidence. Precise categorization of events without affecting the invariant mass shape is crucial in the analysis. Decorrelation of the invariant mass and the output of discriminators (the score of discriminators) is essential for consistent and precise analysis. In this paper, we use distance correlation as an additional loss function to achieve the decorrelation for discriminators and examine various analysis methods. The significance of the Higgs to dimuon signal from gluon fusion is considerably improved by including jet substructure variables.</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"85 3","pages":""},"PeriodicalIF":4.2,"publicationDate":"2025-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-025-13988-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143668360","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":"Collisions and particle dynamics around black holes surrounded by PFDM in STVG","authors":"Isomiddin Nishonov,&nbsp;Javlon Rayimbaev,&nbsp;Saeed Ullah Khan,&nbsp;Muhammad Zahid,&nbsp;Temurmalik Tolibjanov,&nbsp;Inomjon Ibragimov","doi":"10.1140/epjc/s10052-025-13945-0","DOIUrl":"10.1140/epjc/s10052-025-13945-0","url":null,"abstract":"<div><p>Testing dark matter effects on gravity around black holes in the framework of gravity theories through observational data is an essential task of relativistic astrophysical studies. In this work, we first obtain a new spacetime solution for a black hole surrounded by perfect fluid dark matter (PFDM) in modified gravity (MOG). The MOG field is assumed to be a gravitational vector field. We investigate the vector fields with combined effects of PFDM on spacetime properties: event horizon radius, scalar invariants such as the Ricci scalar, the square of the Ricci tensor, and Kretchman scalars. We investigate the circular motion of test particles in the spacetime of the black hole, taking into account the MOG field interaction on the particle geodesics. The energy and angular momentum of the particles corresponding to circular orbits are studied. In addition, we explore how the PFDM and MOG fields change the position of innermost stable circular orbits (ISCOs) and their corresponding energy and angular momentum values. Moreover, we study the energy efficiency rate around the black hole in the Novikov and Thorns thin accretion disc model. We analyze collisional cases of the particles near the black hole and study the effects of the fields on the critical angular momentum in which particles can collide near the black hole and the center-of-mass energy of the colliding particles.</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"85 3","pages":""},"PeriodicalIF":4.2,"publicationDate":"2025-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-025-13945-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143668279","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":"Study of stable dark energy stars in Hořava–Lifshitz gravity","authors":"Krishna Pada Das,&nbsp;Ujjal Debnath","doi":"10.1140/epjc/s10052-025-14059-3","DOIUrl":"10.1140/epjc/s10052-025-14059-3","url":null,"abstract":"<div><p>We study the structure and basic physical properties of non-rotating dark energy stars in Hořava–Lifshitz (HL) gravity. The interior of proposed stellar structure is made of isotropic matter obeys extended Chaplygin gas EoS. The structure equations representing the state of hydrostatic equilibrium i.e., generalize TOV equation in HL gravity is numerically solved by using chosen realistic EoS. Next, we investigate the deviation of physical features of dark energy stars in HL gravity as compared with general relativity (GR). Such investigation is depicted by varying a parameter <span>(omega )</span>, whereas for <span>(omega rightarrow infty )</span> HL coincide with GR. As a result, we find that necessary features of our stellar structure are significantly affected by <span>(omega )</span> in HL gravity specifically on the estimation of the maximum mass and corresponding predicted radius of the star. In conclusion, we can predict the existence of heavier massive dark energy stars in the context of HL gravity as compared with GR with not collapsing into a black hole. Moreover, we investigate the stability of our proposed stellar system. By integrating the modified perturbations equations in support of suitable boundary conditions at the center and the surface of the stellar object, we evaluate the frequencies and eigenfunctions corresponding to six lowest excited modes. Finally, we find that physically viable and stable dark energy stars can be successfully discussed in HL gravity by this study.</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"85 3","pages":""},"PeriodicalIF":4.2,"publicationDate":"2025-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-025-14059-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143668280","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":"Exploring physical properties of anisotropy dependent self-gravitating massive compact stars in (f(mathbb {Q})) gravity","authors":"T. T. Smitha,&nbsp;S. K. Maurya,&nbsp;Baiju Dayanandan,&nbsp;G. Mustafa,&nbsp;Farruh Atamurotov","doi":"10.1140/epjc/s10052-025-14034-y","DOIUrl":"10.1140/epjc/s10052-025-14034-y","url":null,"abstract":"<div><p>In this paper, we present anisotropy-dependent well behaved non-singular solutions for static and spherically symmetric self-gravitating compact objects in the framework of <span>(f(mathbb {Q}))</span> gravity assuming the linear form of <span>(f(mathbb {Q})=-beta _1, mathbb {Q} - beta _2)</span>, where <span>(beta _1)</span> and <span>(beta _2)</span> are coupling constants. In particular, we have considered a physical form of metric potential along with the anisotropy factor dependent on the coupling constant <i>K</i>. The field equations are solved to obtain the three different classes of solutions for different ranges of anisotropy parameter <i>K</i> as <span>(0le K &lt;1)</span>, <span>(K=1)</span>, and <span>(K&gt;1)</span>. The physical behavior of the solution for all cases is analyzed and explored by inspecting physical features, various stability criteria, energy conditions, mass function, etc. successfully with a graphical presentation. In addition, the present model justifies the existence of observed compact objects with masses in the range [2.08 <span>(M_{odot })</span>, 2.83 <span>(M_{odot })</span>], with the upper value located in the mass gap regime as observed in gravitational wave events such as GW190814 and GW200210. The mass–radius and moment of inertia (MI) relation for all three cases are examined in connection with the observational constraints of the massive stars, which are related to the lower mass gap region. The range of predicted radius of the massive stars involved in GW190814 and GW200210 subject to the three cases are found to be as [11.12 km, 15.72 km] and [11.08 km, 15.55 km] respectively. In connection to mass-gap region, GW190814 (Abbott et al. in ApJ 896:L44, 2020) and GW200210 (Abbott et al. in Phys. Rev. X 13(4):041039, 2023) can possess higher moment of inertia, <span>(I = 6.56 times 10^{45})</span> g-<span>(hbox {cm}^{2})</span> and <span>(I = 7.98 times 10^{45})</span> g-<span>(hbox {cm}^{2})</span> respectively for <span>(beta _1=1.2)</span> and <span>(K=1)</span>.\u0000\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"85 3","pages":""},"PeriodicalIF":4.2,"publicationDate":"2025-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-025-14034-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143668343","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":"Constraining mass–radius limit of gravitationally decoupled binary compact star mergers PSR J0952-0607 and GW200210 generated by dual matter density profiles","authors":"S. K. Maurya,&nbsp;M. K. Jasim,&nbsp;Abdelghani Errehymy,&nbsp;Phongpichit Channuie,&nbsp;G. Mustafa,&nbsp;Orhan Donmez","doi":"10.1140/epjc/s10052-025-13917-4","DOIUrl":"10.1140/epjc/s10052-025-13917-4","url":null,"abstract":"<div><p>In this article, we present exact solutions to Einstein’s field equations through a process known as minimally gravitational decoupling (MGD). Our study posits strange quark matter (SQM) as the initial seed source and introduces pseudo-Isothermal (PI) dark matter (DM) as the new source. We derive the metric potentials, deformation functions, and physical quantities of gravitating compact objects, thoroughly analyzing the MGD effect on these quantities. By applying Herrera’s cracking concept and the adiabatic condition, we demonstrate that the anisotropic stellar system we studied, influenced by two interconnected sources, achieves stable equilibrium. Focusing on models related to the mass gap identified in the GW200210 event <span>((2.83^{+0.47}_{-0.42}))</span> and the “black widow” pulsar PSR J0952-0607 <span>((2.35_{-0.17}^{+0.17}))</span>, the fastest known spinning neutron star in the Milky Way, we constrain the mass–radius relationship and moment of inertia values under the MGD effects within the framework of general relativity (GR). Our findings indicate that the maximum allowable mass tends to increase in the lower mass gap region as the MGD effect parameter <span>(beta )</span> and the central DM density <span>(sigma _1)</span> rise. Conversely, this maximum mass decreases with an increase in the bag constant <span>({mathcal {B}}_g,)</span> which correlates with the surface density of SQM in our model. Interestingly, when the stellar structure undergoes deformation due to MGD, it responds differently to the density profiles of DM and SQM. Specifically, as <span>({mathcal {B}}g)</span> increases, SQM tends to inhibit the formation of supermassive compact stars (CSs) governed by MGD and PI-DM. Notably, supermassive CSs can exceed 2 <span>(M{odot })</span> for values of <span>({mathcal {B}}_g le 62.5)</span> <span>(text {MeV},text {fm}^{-3}.)</span> Finally, we conclude that a maximum mass of approximately 3 <span>(M_{odot })</span> in the mass gap region can be attained by incorporating DM and adjusting the MGD effects within the stellar structure under GR. The elevated moment of inertia values suggests a stiffer equation of state (EOS) for the current anisotropic system.\u0000\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"85 3","pages":""},"PeriodicalIF":4.2,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-025-13917-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143655353","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":"Prospects for detection of ultra high frequency gravitational waves from compact binary coalescences with resonant cavities","authors":"Aurélien Barrau,&nbsp;Juan García-Bellido,&nbsp;Thierry Grenet,&nbsp;Killian Martineau","doi":"10.1140/epjc/s10052-025-14026-y","DOIUrl":"10.1140/epjc/s10052-025-14026-y","url":null,"abstract":"<div><p>This article aims at clarifying the situation about astrophysical sources that might be observed with haloscope experiments sensitive to gravitational waves in the 1–10 GHz band. The GrAHal setup is taken as a benchmark. We follow a very pedagogical path so that the full analysis can easily be used by the entire community who might not be familiar with the theoretical framework. Different relevant physical regimes are considered in details and some approximations encountered in the literature are questioned. In particular, we carefully take into account the fast drift of the gravitational wave frequency and the associated experimental limitations of different kinds. This has strong impact on sensitivity estimates. We also relax the usual assumption that only the merging phase should be considered. The distances that can be probed are carefully evaluated, taking into account degeneracies between physical parameters. We conclude that any detection in the near future is probably impossible.\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"85 3","pages":""},"PeriodicalIF":4.2,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-025-14026-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143655352","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":"Investigating late-stage particle production in pp collisions with balance functions","authors":"Alexandru Manea,&nbsp;Claude Pruneau,&nbsp;Diana Catalina Brandibur,&nbsp;Andrea Danu,&nbsp;Alexandru F. Dobrin,&nbsp;Victor Gonzalez,&nbsp;Sumit Basu","doi":"10.1140/epjc/s10052-025-14049-5","DOIUrl":"10.1140/epjc/s10052-025-14049-5","url":null,"abstract":"<div><p>Balance functions have been regarded in the past as a method of investigating the late-stage hadronization found in the presence of a strongly-coupled medium. They are also used to constrain mechanisms of particle production in large and small collision systems. Charge balance functions for inclusive and identified particle pairs are reported as a function of charged particle multiplicity in proton–proton collisions simulated with the PYTHIA8 and the EPOS4 models. The charge balance functions of inclusive, pion, kaon, and proton pairs exhibit amplitudes and shapes that depend on particle species and differ significantly in the two models due to the different particle production mechanisms implemented in PYTHIA and EPOS. The shapes and amplitudes also evolve with multiplicity in both models. In addition, the evolution of the longitudinal rms width and that of balance functions integrals with multiplicity (and average transverse momentum) feature significant differences in the two models.\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"85 3","pages":""},"PeriodicalIF":4.2,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-025-14049-5.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143655356","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":"Autonomous systems and attractor behaviors in non-metricity gravity: stability analysis and cosmic acceleration","authors":"Pooja Vishwakarma,&nbsp;Parth Shah,&nbsp;Kazuharu Bamba","doi":"10.1140/epjc/s10052-025-14040-0","DOIUrl":"10.1140/epjc/s10052-025-14040-0","url":null,"abstract":"<div><p>The cosmological dynamics are rigorously investigated through the systematic application of autonomous system analysis to the gravitational field equations in non-metricity gravity. The systematic procedure to analyze the late-time cosmic acceleration in higher-order non-metricity gravity is demonstrated by exploring non-hyperbolic critical points with the center manifold theory. The stability properties of these critical points are also evaluated based on the analysis of eigenvalues and phase portraits. It is explicitly shown that the stable node can be realized. The critical points of each model are individually analyzed, and their corresponding cosmological implications are derived. The stability properties of these critical points are evaluated based on the analysis of eigenvalues and phase portraits, revealing that each model includes at least one stable node. Furthermore, the evolution plots of the cosmological parameters confirm the models’ capacity to exhibit accelerated expansion.\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"85 3","pages":""},"PeriodicalIF":4.2,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-025-14040-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143655357","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}