The European Physical Journal Plus最新文献

This study aims to provide new insights into the angular momentum dependence of (^{14})C-decay. To achieve this, we perform a systematic analysis of the radioactive decay of radon isotopes via (^{14})C cluster emission, employing the Wentzel–Kramers–Brillouin approximation and introducing the screened Kratzer–Morse potential as an innovative nuclear potential. While the (^{14})C emission from radon isotopes has not yet been identified experimentally, our study extends the classical theory of (alpha )-decay to predict half-lives and branching ratios for (^{14})C-decay in radon isotopes (^{216-223})Rn. The results of this work indicate that low angular momentum states favor (^{14})C emission, and the predicted half-lives are consistent with previous theoretical studies. On the other hand, the calculation of branching ratio relative to (alpha -)decay allowed us to quantify the probability of (^{14})C-decay channel for different values of l. The branching ratios suggest that radon isotopes belonging to the naturally occurring radioactive series are the most favorable regarding (^{14})C emission, especially the (^{222}_{86})Rn, which is prime candidate for potential experimental detection of (^{14})C emission. Due to limited experimental data on (^{14})C emission from radon isotopes, to validate our model we extended our calculations to other cluster decays with available half-lives, including (^{14})C, (^{20})O, (^{22,24,26})Ne, (^{28,30})Mg, and (^{32})Si emissions from heavy nuclei. Our predicted half-lives values for cluster emission are validated by experimental data, especially for low angular momentum values.

It is well known that any well-defined bipartite entanglement measure (mathcal {E}) obeys (gamma )th-monogamy relations Eq. (1.1) and assisted measure (mathcal {E}_{a}) obeys (delta )th-polygamy relations Eq. (1.2). Recently, we presented a class of tighter parameterized monogamy relation for the (alpha )th ((alpha ge gamma )) power based on Eq. 1.1. This study provides a family of tighter lower (resp. upper) bounds of the monogamy (resp. polygamy) relations in a unified manner. In the first part of the paper, the following three basic problems are focused:

1. (i)

   tighter monogamy relation for the (alpha )th ((0le alpha le gamma )) power of any bipartite entanglement measure (mathcal {E}) based on Eq. (1.1);

2. (ii)

   tighter polygamy relation for the (beta )th (( beta ge delta )) power of any bipartite assisted entanglement measure (mathcal {E}_{a}) based on Eq. (1.2);

3. (iii)

   tighter polygamy relation for the (omega )th ((0le omega le delta )) power of any bipartite assisted entanglement measure (mathcal {E}_{a}) based on Eq. (1.2).

In the second part, using the tighter polygamy relation for the (omega )th ((0le omega le 2)) power of CoA, we obtain good estimates or bounds for the (omega )th ((0le omega le 2)) power of concurrence for any N-qubit pure states (|psi rangle _{AB_{1}cdots B_{N-1}}) under the partition (AB_{1}) and (B_{2}cdots B_{N-1}). Detailed examples are given to illustrate that our findings exhibit greater strength across all the region.

Event-by-event fluctuations of the charged particle multiplicity are studied for a wide range of centralities for Au−Au collisions at (sqrt{s_{NN}} = 200hbox { GeV}), Pb−Pb collisions at (sqrt{s_{NN}} = 2.76hbox { TeV}) and 5.02 TeV using the Pythia8 Angantyr model. The centrality dependence of (omega _{ch}) observable, which quantifies the fluctuations in terms of scaled variance, is studied for different pseudo-rapidity ranges and has been compared with those obtained from a simple participant superposition model. The (omega _{ch}) was found to be lower than the expectations from the participant model. The estimate would act like a baseline for current and future measurements of event-by-event fluctuations in the charged particle multiplicities in systems at LHC energies where no de-confined medium of quarks and gluons are formed.

Using CALYPSO code and DFT calculations, the structures, stabilities, electronic and spectral properties of bimetallic AuMg_n⁻ (n = 2–12) are comprehensively studied. It is shown that AuMg_n⁻ clusters evolved from planar configuration to triangular pyramid-base structure, to triangular prism-base empty cage structure, and finally to filled cage motif. Large-sized AuMg_n⁻ clusters are structurally different from their individual Mg clusters, indicating that doping atoms have a greater influence on their structure. The charge transfer from Mg to Au occurs in the AuMg_n⁻ clusters. Stability analysis suggests prominent stability of AuMg₃⁻ and AuMg₉⁻, which have 8 and 18 closed-shell electronic configurations. Bond length calculations show that AuMg₃⁻ and AuMg₉⁻ have a compact structure, meaning that there is a strong atomic interaction. The multi-center bond and Mayer bond order studies indicate a stronger Au–Mg interaction than the Mg–Mg interaction. The spectral properties based on the PES, IR, and Raman spectra have also been discussed.

Graphical abstract

It has been proved that the conventional cyclic Hopfield neural network (CHNN) with three neurons does not exhibit chaotic kinetics. Recently, a memristive CHNN has been developed to generate chaos by replacing two self-connected resistive weights with two memristor adaptive weights. Can two memristor adaptive weights replace the resistive weights of one self-feedback connection and one coupling connection, respectively? In this study, a two-memristor CHNN (TM-CHNN) is presented to generate chaos and planar homogeneous coexisting attractors. TM-CHNN owns a planar equilibrium set, and its stability is periodically distributed over the two memristor’s initial state plane. Using numerical measures, the bifurcation kinetics and typical attractors are revealed, and the planar homogeneous coexisting attractors boosted by memristor’s initial states and kinetic effects caused by non-memristor’s initial states are studied. The numerical results show that TM-CHNN can exhibit chaotic kinetics, especially produce planar homogeneous three-scroll chaotic and multi-periodic attractors, whose elegant homogeneous basins of attraction have exquisite manifold structures and fractal boundaries, and have complex evolution with the change of the memristor’s initial states and non-memristor’s initial states. Additionally, FPGA hardware device is made for implementing TM-CHNN and planar homogeneous coexisting attractors are acquired experimentally to verify the simulated results.

This paper considers the Darcy–Forchheimer flow over a micropolar nanofluid by using an intelligent backpropagated neural network with Levenberg–Marquardt scheme. The PDEs governing the DFF-MNFM are reduced into ODEs through some appropriate transformations. A reference dataset is prepared from HAM by changing several key parameters, such as the porosity parameter (γ), Reynolds number (Re), coupling parameter (N₁), rotation parameter (Kr), coefficient of inertia (Fr), viscosity gradient parameter (N₂), and Brownian motion parameter (Nb), for all proposed IBNN-LMS scenarios. The estimated solutions of the IBNN-LMS are analyzed and compared with reference results. The results suggest that for high values of the Reynolds number, Re, the fluid velocity is increased at the surface, and with Kr, increasing velocity on the surface of the fluid increases but decreases beyond the surface. A rise in the value of γ enhances velocity closer to the surface while diminishing the velocity beyond the surface distance. The rise of N₁ enhances the speed of the microrotation of fluid closer to the surface. In addition, the higher temperature and concentration profiles enhance the value of Nb. For the validation of IBNN-LMS approach, its efficiency is justified through convergence analysis of MSE, regression indices, and error spectrum evaluations that represent its robustness in solving complicated fluid flow problems.

We study the motion of charged test particles around a magnetized neutron star described by the Schwarzschild gravitational field of mass M and a dipole magnetic field characterized by parameter b, representing the ratio of electromagnetic to gravitational forces. The neutron star’s radius is assumed at (R=3M). Circular orbits “in” and “off” the equatorial plane, determined by the dipole field’s symmetry plane, are analyzed based on background and particle parameters; their stability against radial and latitudinal perturbations is established. The existence of chaotic charged particle motion in belts around off-equatorial orbits, influenced by sufficiently strong repulsive magnetic force, is demonstrated. The belts’ distance from the neutron star varies with parameter b for different charged particles. Frequencies of epicyclic oscillatory motion related to “in” and “off” equatorial circular orbits, alongside the orbital frequency, are determined. The magnetically modified geodesic model is applied to fit observational data from twin-peak, high-frequency quasi-periodic oscillations in binary systems containing neutron stars. Rough fitting to the data for circular orbits for particles under magnetic attraction (repulsion) is shown. The possible fittings imply strong limits on the magnetic parameter, (b sim 0.01) ((b sim -10)) for magnetic attraction (repulsion), suggesting minor influence of electromagnetic forces and test particles with small specific charges like dust or plasmoids in strong magnetic fields around neutron stars.

The occurrence of singularities at the centers of black holes suggests that general relativity (GR), although a highly successful model of gravity and cosmology, is inapplicable. This is due to the breakdown of the equivalence principle. Gauss-Bonnet (GB) action is the simplest extension of GR as it possesses second-order equations of motion and is devoid of ghosts. However, in 4-D, the GB action is topological. Recently, Glavan and Lin proposed a mathematical framework that transforms the 4-D GB gravity theory into a non-topological one. However, it has been argued that without a canonical way to choose 4-D from the higher-dimensional space, such a GB gravity is not well-defined in 4-D. Naturally, there has been much interest in having a systematic procedure for making the 4-D GB term non-topological, such as using the counterterm regularization method in 4-D, regularization with the dimensional derivative, and Kaluza-Klein reduction. The current work takes a step in addressing this issue by demonstrating that the rescaling of the GB coupling (alpha rightarrow alpha /(D - 4)) arises from the self-energy correction of gravitons in 4-D using only the established quantum field theoretic techniques. To keep things transparent, we focus on the linearized theory of gravity coupled with matter fields. By computing the one-loop self-energy correction of gravitons induced by the matter fields, we explicitly provide the origin of the prescription provided by Glavan and Lin. We compare the procedure with other regularization procedures like Kaluza-Klein dimensional reduction and conformal scaling regarding the strong coupling problem. Our work naturally opens a new window to considering 4-D Einstein Gauss-Bonnet gravity as the most straightforward modification to GR.

The anomalous scattering of lump waves governed by the Date–Jimbo–Kashiwara–Miwa (DJKM) equation is explored via two distinct methods. The second-order anomalously scattered lump is derived by degenerating the M-lump solution under the limit of infinite phase. Higher order anomalously scattered lumps are obtained through the degeneration of lump chains described by infinite periods, with analyses of two types of degenerate lump chains. A thorough asymptotic analysis is employed to investigate both the dynamic behavior and scattering angles of the anomalous scattering phnomena. Notably, the triangular structures of higher order lumps are found to be closely related to the Yablonskii-Vorob’ev polynomials. These insights may deepen our understanding of the intrinsic characteristics of lump waves.

The spatiotemporal complexity of a system of interacting species, influenced by hunting cooperation and the additive Allee effect, has garnered significant attention within the ecological framework. This study investigates whether interactions among species can stabilize the dynamics of environmental communities and promote coexistence, employing a cross-diffusion-driven species interaction model. The local and global bifurcation behaviour of the proposed system and the stability of all potential equilibrium points in the absence of diffusion have been comprehensively examined. Numerical simulations have been conducted to validate the analytical findings and assess the applicability of the cross-diffusive model. In a two-dimensional plane, the evolution of diffusion-driven pattern generation, known as black-eye replication, around the coexistence equilibrium point has been presented. Furthermore, it has been demonstrated that species interactions within the context of cross-diffusion can exacerbate the instability dynamics of ecological populations by generating spatial patterns. The results underscore the crucial role of cross-diffusion-driven instability in maintaining ecosystem diversity and structure.