The European Physical Journal Plus最新文献

The main goal of the present study is to obtain an approximate analytical solution for a quasi-linear hyperbolic system of PDEs using the power series method. This system of PDEs pertains to the dynamics of propagation of cylindrical shock wave within a rotating axisymmetric nonideal gas. The gas, presumed to be under isothermal condition, is influenced by azimuthal magnetic and gravitational fields. The analysis incorporates variations in density, magnetic pressure, azimuthal, and axial fluid velocities according to a power law with distance from the symmetry axis in the undisturbed medium. The approximate analytical solution is obtained by expressing the flow variables as a power series. The primary focus of the study is on examining the ZOA and FOA to the solutions, including an explicit solution for the ZOA case. Figures illustrating the behavior of the flow variables behind the shock front are presented for the ZOA. Further, the investigation explores the impact of nonideal parameter, adiabatic exponent, shock Cowling number, gravitational parameter, rotational parameter and ambient density variation exponent on the flow variables.

The present study investigates the effects of external fields, including magnetic, electric, and non-resonant high-frequency intense laser fields, on the binding energies of the heavy hole excitons and the (hh1-e1) interband transitions from the ground state energy level of the heavy hole to the ground state energy level of the electron in (text{GaAs}/{text{Al}}_{x}{Ga}_{1-x}text{As}) Gaussian type single quantum well. The study also considers the roles of the well width and the structure parameter. The results obtained show that the geometrical shape of the structure and the applied external fields are very effective tools on the excitonic binding and excitonic absorption spectra. From the results obtained, it was observed that the bandgap of semiconductor materials can be tuned by changing the structural parameters along with the applied external fields according to the purpose. This tunability enables the development of devices with optimized performance and new functionalities, thus driving innovation in various fields of technology.

A novel procedure for evaluating Wigner coupling coefficients and Racah recoupling coefficients for U(4) in two group–subgroup chains is presented. The canonical (rm U(4) supset U(3)supset U(2)supset U(1)) coupling and recoupling coefficients are applicable to any system that possesses U(4) symmetry, while the physical (mathrm{U(4)} supset textrm{SU}_{mathrm{S}}(2) otimes textrm{SU}_{mathrm{T}}(2)) coupling coefficients are more specific to nuclear structure studies that utilize Wigner’s supermultiplet symmetry concept. The procedure that is proposed sidesteps the use of binomial coefficients and alternating sum series and consequently enables fast and accurate computation of any and all U(4)-underpinned features. The inner multiplicity of a (S, T) pair within a single (mathrm U(4)) irreducible representation is obtained from the dimension of the null space of the (mathrm{SU(2)}) raising generators, while the resolution for the outer multiplicity follows from the work of Alex et al. on (mathrm U(N)). It is anticipated that a C++ library will ultimately be available for determining generic coupling and recoupling coefficients associated with both the canonical and the physical group–subgroup chains of U(4).

The article presents an experimental study investigating the nuclear radiation attenuation properties of concretes doped with different percentages (4–8–12–16–20%) of iron (Fe), antimony (Sb), and lead (Pb), prepared using different cement types (CEM I and CEM IV). The samples were irradiated using Am-241 and Ba-133 radioactive sources, and the mass attenuation coefficient (MAC), effective atomic number (Z_eff), effective electron density (N_eff), half-value layer (HVL), and mean free path (MFP) were both theoretically and experimentally calculated. WinXCom program was used for theoretical calculations. The samples were placed between the detector and the radiation source in the experimental measurements, and transmission measurements were taken. In addition, the samples’ Exposure (EBF) and Energy Absorption (EABF) Buildup Factors values were calculated theoretically and their changes according to energy and penetration depth were evaluated. The samples with higher percentages of Fe, Sb, and Pb have higher effective atomic numbers and electron densities, leading to improved radiation shielding performance. The study found no significant difference in radiation shielding performance between concretes made with CEM I and CEM IV cement types. Among the concretes, those with 20% Sb (Sb20) and 20% Pb (Pb20) dopes exhibited the best radiation attenuation capabilities. Sb-doped concretes showed promising results, with a performance close to that of Pb-doped concretes despite Sb’s lower atomic number, making it a potentially more cost-effective and environmentally friendly alternative to lead in radiation shielding applications.

The freeze-out parameters are extracted by analyzing the transverse momentum ((p_T)) spectra of (pi ^+) and (pi ^-) measured in proton–proton (pp) collisions at NA61/SHINE Collaboration using the blast wave model with Tsallis statistics (TBW) across various rapidity segments. We extracted the kinetic freeze-out temperature ((T_0)), transverse flow velocity ((beta _T)), velocity flow profile, and the non-extensive parameter (q). We also calculated the initial temperature ((T_i)) of the emission source of the final state particles by the string percolation theory as well as the mean transverse momentum ((langle p_T rangle )) of the produced particles. We have attempted to gain some insights into the expansion parameters of the system formed in the final state of the collision. We observed that the (T_i), (langle p_T rangle ), (T_0), and (beta _T) decrease from mid-rapidity toward forward rapidity region, while the flow profile parameter increases. We observed the kinetic freeze-out to be the reflection of the emission source of the final state particles and mean (p_T). (T_0) along with the (T_i), mean (p_T) and the (beta _T) increases from lower energies up to 8.8 GeV, and after that, they remain unchanged. However, the velocity flow profile has the opposite behavior with increasing energy up to 8.8 GeV. The increment in the temperatures from lower energies up to 8.8 GeV shows the increasing excitation degree of the interacting system with increasing energy, while 8.8 GeV energy is seen to be the energy where the system reaches a critical energy density and the phase transition is supposed to occur. Furthermore, the (beta _T) is related to the equation of states, and its saturation evinces toward the conformal equation of state.

The Extremely Brilliant Source (EBS), the first high-energy 4th-generation synchrotron radiation source, constructed at the ESRF and based upon the novel concept of a Hybrid Multi-Bend Achromat (HMBA), has started user operation on August 25th, 2020. We report here on selected recent scientific results exploiting the greatly improved performances of this novel X-ray source.

Relativistic calculations of the photoionization cross-sections are carried out for the ground state 1s²2p⁶3s² (¹S₀) and first three excited states 1s²2p⁶3s3p (³({text{P}}_{{0,1,2}}^{{text{o}}})) of Mg-like Ca IX ion using the Breit–Pauli R-matrix (BPRM) approach. Configuration interaction method (CIV3) is used to construct the target wavefunctions. A total of lowest lying 21 fine structure levels corresponding to 2p⁶nl (3 ≤ n ≤ 5) configurations are considered for the expansion of target wavefunctions. Reported target state eigen energies of the 21 fine structure levels of core ion Ca X agree with the available data. To assess the accuracy of our BPRM results, we have also performed similar calculations using the fully relativistic Dirac atomic R-matrix code (DARC) for the ground state of Mg-like Ca IX ion. Further, relativistic distorted wave (DW) method is also used for the comparison purpose, and a good agreement has been found with the R-matrix results. The quantum number (n), resonance width (Γ) and resonance energies (E_r) of the 3dnp (³P₁, ¹P₁, ³D₁, ¹D₂), 3dnf (³P₁, ¹P₁) and 4snp (³P₂, ³P₀, ³P₁, ¹P₁) series have also been predicted using Quigley and Berrington (QB) method. We believe that the present results will be helpful for modeling and diagnostics of laboratory and astrophysical plasmas.

Within the so-called scaled quantum theory, the standard bouncing ball problem is analyzed under the presence of a gravitational field and harmonic potential. In this framework, the quantum-classical transition of the density matrix is described by the linear scaled von Neumann equation for mixed states and after it has been particularized to the case of pure states. The main purpose of this work is to show how this theory works for conservative systems, and the quantum-classical transition is carried out in a continuous and smooth way, being equivalent to a nonlinear differential wave equation which contains a transition parameter ranging continuously from one to zero and covering all dynamical regimes in-between the two extreme quantum and classical regimes. This parameter can be seen as a degree of quantumness where all intermediate dynamical regimes show quantum features but are fading gradually when approaching to the classical value.

This research delves into the intricate analysis of the Kaup-Newell equation when affected by multiplicative white noise within birefringent fibers, a topic of growing importance in modern communication systems. This study introduces a novel approach to this model, which is reported in this paper for the first time; the additional impact of the multiplicative white noise effect is also incorporated. Through applying two distinct methodologies, the enhanced direct algebraic method and the new projective Riccati equations method, this investigation illuminates the dynamic behaviors exhibited by this equation under stochastic conditions. The outcomes of this rigorous mathematical exploration encompass the identification of bright, dark, and singular soliton solutions and straddled soliton solutions. Furthermore, the research uncovers Jacobi elliptic doubly periodic solutions and Weierstrass elliptic doubly periodic function solutions. The comprehensive nature of these results advances the understanding of nonlinear wave propagation in birefringent fibers. It provides a theoretical groundwork for future experimental and practical applications in optical fiber technology. This study underscores the significance of integrating noise considerations into modeling optical fiber dynamics, which could have profound implications for developing more resilient and efficient communication systems.

This paper presents a mathematical perspective on constructing the off-energy-shell transition matrix for motion in the Deng–Fan potential. As a basic prerequisite, the Deng–Fan off-shell Jost and physical solutions are derived in their maximal reduced form by considering the differential equation approach to the problem. Because of the nature of the Deng–Fan potential and the considered screened centrifugal barrier, we do some important mathematical manipulations that enable us to find the analytical expressions of these off-shell quantities, which are consistent with certain limiting conditions. To the author’s knowledge, the formulation of the Deng–Fan off-shell T-matrix is new in the literature. The effectiveness of these expressions is tested by computing the phase observables and T-matrix elements of n-p system, which confirms the previously reported findings.