Few-Body Systems最新文献

We report on our new models for photoproduction and electroproduction of kaons off the proton and neutron target, focusing first on the (K^+Lambda ) channel and then extending the analysis to (Sigma ) photoproduction channels. For the proper treatment of the exchanges of higher-spin resonances, we opted for the so-called consistent formalism and in order to partially account for the unitarity corrections at the tree level, we introduced energy-dependent widths of nucleon resonances. For selecting the appropriate set of resonances, we used regularization methods known from machine learning, the Least Absolute Shrinkage Selection Operator and Ridge regression.

This study examines the dynamics of the third body in an elliptic restricted three-body problem (ERTBP) framework, taking into account perturbations from radiation pressure, oblateness, and elongation of the primary bodies, as well as disk-like structures. The objectives are to determine the positions and stability of the equilibrium points, assess how these points shift under the influence of perturbations, and evaluate the dependence of their stability on the orbital eccentricity and perturbation parameters. The ERTBP model is modified to include a radiating, oblate primary body and an elongated secondary body modeled as a finite straight segment, alongside perturbations from a surrounding disk. The system’s equations of motion are numerically solved using parameters from perturbed and classical cases. Equilibrium positions are computed over a range of eccentricities and perturbation values, and stability is analyzed using linearized equations and eigenvalue methods. In all cases, we have found three collinear ((L_1), (L_2), (L_3)) and two non-collinear ((L_4), (L_5)) equilibrium points solutions. The inclusion of radiation, oblateness, elongation using a finite straight segment, and disk perturbation systematically displaces each equilibrium point from its classical location, with the magnitude and direction of the displacement varying with the perturbation parameter. Stability analysis confirms that the collinear points remain linearly unstable under all tested conditions. Meanwhile, non-collinear points are stable under a specific condition. We investigate the stability boundary of these points as a function of orbital eccentricity and we found there is a critical range of eccentricity values within which stability is preserved.

Few-atom systems play an important role in understanding the transition from few- to many-body quantum behaviors. This work introduces a new approach for determining the energy spectra and eigenstates of small harmonically trapped single-component Bose and Fermi gases with additive two-body zero-range interactions in one spatial dimension. The interactions for bosons are the usual (delta )-function interactions while those for fermions are (delta )-function interactions that contain derivative operators. Details of the derivation and benchmarks of the numerical scheme are presented. Extensions to other systems are discussed.

We have treated the collision between two hydrogen atoms in the ground states using atomic-orbital close-coupling calculations within the impact parameter method. The cross sections for projectile excitation to 2s and 2p, (hbox {H}^-) formation in the projectile, and projectile ionization are calculated with a larger basis set than previous calculations in the energy range of 1 to 30 keV. The excitation results do not agree with experimental data. The (hbox {H}^-) formation results agree well with experimental data, and the ionization results are also acceptable.

Few-body scattering and loosely bound states in the vicinity of an isolated narrow Feshbach resonance are well described by a conceptually simple contact interaction two-channel model, where an open atomic continuum channel is coupled to a closed molecular channel. However, real systems are often characterized by the multiplicity of both continuum and molecular channels. Here we develop a systematic framework to deal with multi-channel problems within a contact interaction approximation. We demonstrate the differences and similarities of adding a molecular or atomic channel to the two-channel model. By means of direct comparison, we show that while an additional atomic channel makes loosely bound states shallower, an additional molecular channel makes them more deeply bound. This approach facilitates the study of the influence of multi-channel environments on few-body physics in a systematic manner by gradually increasing the level of complexity. Furthermore, we account for real atomic systems whose understanding can benefit from this study.

In this paper, we present the Sakata-Taketani equation within the framework of conformable derivatives. We propose conformable Lagrangian and Hamiltonian densities that incorporate both temporal and spatial conformable derivatives, we have obtained exact analytical solutions for several important physical scenarios: the free Sakata-Taketani equation in both purely temporal conformable and full space-time conformable cases, the confined Sakata-Taketani particle in an infinite potential well with conformable spatial derivatives, and systems subject to power-law external potentials. The solutions reveal how conformable derivatives modify energy spectra, alter wavefunction distributions.

Using representation–theoretic techniques associated with the (mathfrak {su}(1,1)) symmetry algebra, we construct Perelomov coherent states for the Dunkl–Klein–Gordon equation in its canonical form, which is free of first–order Dunkl derivatives. Our analysis is restricted to the even–parity sector and to the regime where the curvature constant ( R ) is much smaller than the system’s kinetic energy. The equation under consideration emerges from a matrix–operator framework based on Dirac gamma matrices and a universal length scale that encodes the curvature of space via the Dunkl operator, thereby circumventing the need for spin connections in the Dirac equation.

In the present work, we predict the existence of new types of hydrogenlike matter, including hydrogenlike atoms ((pi ^+e^-), (K^+e^-), (D^+e^-)), hydrogenlike molecular ions ((pi ^+pi ^+e^-), (K^+K^+e^-), (D^+D^+e^-)) and hydrogenlike molecules ((pi ^+pi ^+e^-e^-), (K^+K^+e^-e^-), (D^+D^+e^-e^-)). By solving the Schrödinger equation, the binding energy of hydrogenlike atoms is obtained as (E_n=-frac{1}{2n^2}). For hydrogenlike molecular ions and molecules, the variational method is employed to calculate the binding energies, i.e., (E_+=-0.587) and (E_0=-1.139) for hydrogenlike molecular ions and molecules, respectively. And the bond lengths for hydrogenlike molecular ions and molecules are also calculated, whose values are 2.003 and 1.414, respectively. Here all the quantities are in atomic units for convenience. In addition, the strong interaction between the two constituent mesons is considered in our calculations, where we find that its influence on the hydrogenlike molecular ions and molecules can be neglected. Comparisons of hydrogenlike molecular ion and molecule with the systems governed by the strong interaction are made, which suggests the possible existence of doubly heavy triquark, hidden heavy-flavor tetraquarks and doubly heavy tetraquarks. Hopefully, these types of matter would be observed in the future with the improvement of accuracy in the high energy physical experiments.

We investigate the plasma sscreening effects on the van der Waals two-body dispersion coefficients, C(_{textrm{6}}), for interactions among heliumlike atoms (Z(=)2-10), using highly accurate correlated exponential wave functions. Two different plasma models, namely, the Debye plasma model and quantum plasma model are considered. The Debye-Hückel potential is used to model the Debye plasma environment, and the exponential cosine screened Coulomb potential is used to model the quantum plasma environment. The dispersion coefficients C(_{textrm{6}})for interactions among screened-heliumlike atoms (Z(=)2-10) in their ground states for different screening parameters, are reported for the first time in the literature.

In this work, we solve the nonrelativistic symplectic Schrödinger-type equation for a two-body system within the framework of symplectic quantum mechanics. By employing a Lie algebraic approach, we obtain an explicit solution for the wave function in phase space. Subsequently, we derive the corresponding Wigner function and analyze its behavior. As an application, we investigate the heavy quark-antiquark system, specifically the (coverline{c}) meson, which interacts through a linear term of the Cornell potential model. The Wigner function is studied to describe the ground state of the meson. Furthermore, our results indicate that small variations in kinetic momentum significantly affect the maximum possible relative quark-antiquark separation q in (textrm{GeV}^{-1}). This suggests the existence of an upper limit for the Wigner function curves of the heavy quark-antiquark pair, dependent on the kinetic energy, as illustrated in our graphical analysis. These findings align with previous results in the literature. We also emphasize that the methodology adopted for the study of this equation is based on the theory of Lie groups for differential equations, and with application in the calculation of conservation laws using the Noether theorem.