Parametric control of electron-positron acoustic solitons: Bridging quantum plasma theory and compact stellar objects

This study investigates the parametric control of electron-positron acoustic solitons (EPAS) in a magnetized four-component quantum plasma comprising electrons, positrons, ions, and charged dust grains. Employing the reductive perturbation technique and small-k expansion method, we derive a modified Zakharov-Kuznetsov (ZK) equation to analyze the nonlinear dynamics and stability of EPAS. The phase velocity, nonlinearity, and dispersion coefficients are critically influenced by plasma parameters such as the ion-to-electron density ratio (δ), dust-to-electron density ratio (μ), positron-to-electron Fermi energy ratio (σ), and effective-to-ion temperature ratio (γ). Our results reveal that compressive and rarefactive solitons emerge depending on the interplay between restoring forces and inertia, with soliton amplitude and width exhibiting distinct trends under varying parametric conditions. The instability growth rate of EPAS is also examined, demonstrating sensitivity to magnetic field strength and propagation angle. These findings bridge theoretical plasma physics with astrophysical observations, offering insights into wave behavior in environments like neutron star magnetospheres and white dwarf atmospheres. The study underscores the role of quantum degeneracy, relativistic effects, and dust-induced charge depletion in shaping nonlinear wave phenomena.