The European Physical Journal Plus最新文献

In this study, we investigate the structural properties of the Ru isotopic chain (^88-114Ru) using the Interacting Boson Model (IBM). By analyzing quadrupole interaction probabilities and d-boson occupation, we explore the competition between pairing correlations and nuclear deformation. We classify isotopes based on their agreement with the U(5) dynamic limit. The results reveal a systematic trend: Nuclei far from magic numbers exhibit enhanced quadrupole interaction probabilities, whereas those near magic numbers show increased d-boson occupation, reinforcing the link between nuclear deformation and collective excitation mechanisms. Additionally, the analysis of the second 0⁺ state provides further insights into shape coexistence, establishing its role as a structural indicator in the transition between spherical and deformed configurations. This study not only contributes to understanding Ru isotopes but also lays the foundation for further exploration of nuclear phase transitions and structural evolution in medium-mass nuclei.

Neutrino mass origin remains one of the central unsolved puzzles in particle physics. Leading mechanisms were established by the early 2000s, with limited essential breakthroughs observed in the past twenty years. These approaches often rely on the unobserved Higgs triplet field, non-renormalizable operators or the hypothetical coupling of the left-handed and right-handed neutrinos. In this work, we address these fundamental challenges by proposing a novel low-scale mechanism where neutrino masses are generated through a renormalizable, Higgs doublet-mediated interaction between the SU(2) lepton doublet and the CP conjugate singlet, distinct from the conventional Higgs–Yukawa coupling formed between the lepton doublet and singlet. Through a fresh extension of the Standard Model (SM) where the SU(2) doublet and singlet representations of neutrinos are slightly misaligned with their chiral fields, we were able to provide a theoretically coherent explanation for the Majorana neutrino mass generation without a priori assumption that neutrinos are their own antiparticles. Our model further eliminates the coupling of the left-handed and right-handed neutrinos and meanwhile substantially reduces the fine-tuning of Yukawa couplings. We conclude by highlighting the key implications of our findings, including the minimal mixing between active and sterile neutrinos (consistent with current experiments) and the potential of the present SM extension in decoding the flavor mixing and CP-violating phases.

Beginning with a 2D linear model with the Lagrangian action consisting of the sum between that of a topological field theory of BF-type and that of a system of massless real scalar fields, one determines the general interaction vertex that can be added to the initial theory, while preserving the field spectrum and the range of independent degrees of freedom. The analysis is performed using the deformation technique within the framework of antifield-BRST symmetry, aided by specific techniques of local (co-)homology. In the considered space-time dimension, it is shown that the scalar fields from the BF field spectrum ’generate’ some ’gravitational potential facet’ in the context of the interaction with the considered matter fields.

The transverse momentum spectra of particles coming from high-energy collisions can generally be divided into the lower and higher p_T parts, where mostly the soft and hard processes contribute, respectively. In this paper, we have presented the new combined Tsallis-Hagedorn function with transverse flow in an attempt to describe better the longer range of p_T spectra of hadrons. This new model function combines thermodynamically consistent Tsallis distribution with embedded transverse flow and QCD inspired Hagedorn function, assuming independence of the soft and hard processes, which contribute to the lower and higher parts of p_T distribution. In order to study an influence of the p_T fit range on the values of the parameters and quality of fits, the experimental midrapidity transverse momentum distributions of the charged pions and kaons, protons and antiprotons in ten centrality classes in Pb + Pb collisions at (sqrt {s_{nn} }) = 5.02 TeV, measured by the ALICE Collaboration, have been analyzed using simultaneous minimum χ² fits by the introduced combined Tsallis-Hagedorn function with transverse flow in two p_T fit ranges up to 5 and 8 GeV/c. The results obtained using combined Tsallis-Hagedorn function with transverse flow for kinetic freeze-out temperature and average transverse flow velocity as well as non-extensivity parameter q, and dependencies of these parameters on collision centrality, have been compared systematically with those obtained using thermodynamically consistent Tsallis function with embedded transverse flow. On the whole, both functions have resulted in comparably good fit qualities and similar trends of collision centrality dependencies of the extracted kinetic freeze-out parameters, confirming the important findings of the earlier work in both shorter and longer p_T fit ranges.

This study presents the green synthesis and comprehensive characterization of gold nanoparticles (AuNPs) using aqueous extracts derived from Sorbus aucuparia L. (Rowan berries) harvested in Trabzon province, Türkiye. Initially, 100 g of the dried fruit material were thoroughly washed with deionized water to eliminate dust and surface contaminants and subsequently dried under appropriate conditions. The dried fruits were boiled in 500 mL of deionized water for 60 min to obtain the bioactive extract, which was then filtered using Whatman filter paper. Chloroauric acid trihydrate (HAuCl₄·3H₂O, 99.9%) was used as the gold precursor at three different concentrations: 0.1 mM, 0.2 mM, and 0.3 mM. To each concentration, 0.3 mL or 0.5 mL of the fruit extract was added. The reaction mixtures were prepared by combining the extract and 70 mL of the HAuCl₄ solution and stirred gently to ensure uniform dispersion. Microwave-assisted synthesis was employed using a standard household microwave oven at power levels of 180 W, 360 W, and 600 W, for durations varying between 1 and 15 min. Each experimental condition was repeated in triplicate to ensure reproducibility and statistical reliability. Characterization of the resulting AuNPs was performed using UV–Vis spectroscopy, TEM, FTIR, XRD, and Zetasizer analysis. The optimal synthesis conditions were identified as 0.1 mM HAuCl₄ concentration with 0.3 mL of Sorbus aucuparia L. extract under 360 W microwave irradiation. UV–Vis analysis revealed a distinct surface plasmon resonance (SPR) peak, confirming the successful formation of gold nanoparticles. TEM images showed that the AuNPs were predominantly spherical with a mean particle size of 17.750 ± 3.606 nm, ranging from 10.230 to 28.687 nm. The crystallite size calculated from XRD was approximately 12.38 nm. Dynamic Light Scattering (DLS) analysis demonstrated an average hydrodynamic diameter of 45.25 ± 7.9 nm in aqueous suspension. The zeta potential was measured at − 15.2 ± 7.49 mV, indicating moderate colloidal stability. The polydispersity index (PDI) was found to be 0.581, suggesting a moderately polydisperse system. The produced AuNPs remained stable without significant aggregation or precipitation for a period of 2–3 months when stored under ambient conditions.

In this work, a massive scalar field theory incorporating Lorentz violation is investigated. The symmetry breaking is introduced via a background traceless antisymmetric tensor. Within the framework of Thermo Field Dynamics (TFD), the effects of space-time compactification are explored, allowing the simultaneous treatment of thermal and finite-size phenomena. The resulting modifications to the energy-momentum tensor and Feynman propagator are analyzed, leading to Lorentz-violating corrections to the Stefan-Boltzmann law and the Casimir effect. This unified approach highlights the interplay between temperature, spatial constraints, and Lorentz-violating backgrounds in shaping the behavior of quantum fields.

We embark on computing the longitudinal magnetoconductivity within the semiclassical Boltzmann formalism, where an isotropic triple-point semimetal (TSM) is subjected to collinear electric ((varvec{E})) and magnetic ((varvec{B})) fields. Except for the Drude part, the B-dependence arises exclusively from topological properties like the Berry curvature and the orbital magnetic moment. We solve the Boltzmann equations exactly in the linear-response regime, applicable in the limit of weak/nonquantising magnetic fields. The novelty of our investigation lies in the consideration of the truly multifold character of the TSMs, where the so-called flat-band (flatness being merely an artefact of linear-order approximations) is made dispersive by incorporating the appropriate quadratic-in-momentum correction in the effective Hamiltonian. It necessitates the consideration of interband scatterings within the same node as well, providing a complex interplay of intraband, interband, intranode, and internode processes, offering an overwhelmingly rich set of possibilities. The exact results are compared with those obtained from a naive relaxation-time approximation.

This study investigates the dynamics of tuberculosis (TB) transmission in high-density populations with suboptimal hygiene conditions, focusing on India as a representative setting. We develop a transmission model incorporating both weak and strong kernel functions to represent distributed time delays in TB latency, along with vaccination effects. By analyzing stability around the TB-free equilibrium with respect to the time delay arising from the latent phase, we identify critical bifurcation thresholds for local stability. The model exhibits a Hopf bifurcation at the tuberculosis-existence equilibrium when the latency delay exceeds this critical value, indicating oscillatory disease dynamics. Numerical simulations validate our analytical findings and provide insights into the interplay between vaccination parameters, latency periods, and TB control. The results offer valuable guidance for optimizing vaccination strategies and timing interventions in TB-endemic regions.

The dynamics of a fluid confined between two concentric cylinders are investigated using a novel approach based on recursive equations. First, for a system constrained by no radial mass transfer, an exact analytical solution is formulated. When compared against the classical solution derived from the Navier–Stokes equations, our model shows increasing deviation as the ratio of the outer-to-inner radii grows. Subsequently, the model is extended to permit a radial mass flow, and a corresponding solution is proposed. The solution is enhanced by proposing a variable radial mass flow model, where a comparison with experiment provides the rate of variation. A primary advantage of this methodology is its enhanced accuracy in describing the steady flow profile near the inner cylinder, a region where both Navier–Stokes and our previous obtained solutions with no radial mass transfer can be less precise. The proposed framework is readily applicable and extendable, holding promise for theoretical studies of similar confined flow phenomena.

In this study, we investigate the natural convection heat transfer enhancement capabilities of hybrid nanofluids in curved cooling chambers equipped with four heat pipes. The research focuses on examining the effects of the Rayleigh number (Ra), nanoparticle volume fraction (ϕ), and different heat pipes arrangements on heat transfer characteristics. The findings reveal that increasing the Rayleigh number significantly enhances convective heat transfer, leading to a more uniform temperature distribution within the chamber. Higher Ra values promote vigorous fluid motion, improving heat dissipation and reducing thermal gradients. Introducing nanoparticles into the base fluid increases thermal conductivity, enhancing heat transfer performance. A higher nanoparticle volume fraction is particularly effective in boosting the overall heat transfer rate, indicating potential for optimizing fluid composition for improved thermal management. Among the 14 heat pipe arrangements analyzed, specific configurations demonstrate superior thermal management by maximizing contact area between heat pipes and the cooling chamber, the Case 1 and Case 6 consistently providing high heat transfer performance. The combined effect of optimized heat pipe arrangement and hybrid nanofluids results in a synergistic enhancement of heat transfer capabilities, offering improved thermal conductivity and more effective utilization of chamber space, thus providing advanced solutions for thermal management applications.