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Abstract In this work, we investigate the dynamics of a scalar field in the nonintegrable ϕ 4 model, restricted to the half-line. Here we consider singular solutions that interpolate the Dirichlet boundary condition ϕ(x = 0, t) = H and their scattering with the regular kink solution. The simulations reveal a rich variety of phenomena in the field dynamics, such as the formation of a kink-antikink pair, the generation of oscillons by the boundary perturbations, and the interaction between these objects and the boundary, which causes the emergence of boundary-induced resonant scatterings (for example, oscillon-boundary bound states and kink generation by oscillon-boundary collision) founded into complex fractal structures. Linear perturbation analysis was applied to interpret some aspects of the scattering process. We detected the presence of two shape modes near the boundary. The power spectral density of the scalar field at a fixed point leads to several frequency peaks. Most of them can be explained with some interesting insights for the interaction between the scattering products and the boundary.

Abstract We investigate kink-antikink collisions in a model characterized by two scalar fields in the presence of geometric constrictions. The model includes an auxiliary function that modifies the kinematics associated with one of the two fields. An important fact is that one of the fields can be solved independently, being responsible for changing the internal structure of the second one. We performed several collisions and observed the presence of resonance windows for small values of the parameters. Furthermore, we have been able to show the alternation between the appearance of oscillating pulses, as well as the annihilation and formation of kink-antikink pairs when the geometric constriction is more pronounced. The study of kink dynamics in models with geometric constrictions is connected with issues of interest such as domain wall formation and magnetization at the manometric scale.

Abstract We study kink-antikink collisions in a particular case of the double sine-Gordon model depending on only one parameter r. The scattering process of large kink-antikink shows the changing of the topological sector. For some parameter intervals we observed two connected effects: the production of multiple antikink-kink pairs and up to three solitary oscillations. The scattering process for small kink-antikink has several possibilities: the changing of the topological sector, one-bounce collision, two-bounce collision, or formation of a bion state. In particular, we observed for small values of rand velocities, the formation of false two-bounce windows and the suppression of true two-bounce windows, despite the presence of an internal shape mode.

Abstract We study the non-integrable 𝜙6 model on the half-line. The model has two topological sectors. We chose solutions from just one topological sector to fix the initial con­ ditions. The scalar field satisfies a Neumann boundary condition 𝜙 x (0, t) = H. We study the scattering of a kink (antikink) with all possible regular and stable boundaries. For H = 0 the results are the same observed for scattering for the same model in the full line. For H ≠ 0, sensible modifications appear in the dynamics with several possibilities for the out­put depending on the initial velocity and the boundary. Our results are confronted with the topological structure and linear stability analysis of kink, antikink and boundary solutions.

Abstract We study the non-integrable 𝜙6 model on the half-line. The model has two topological sectors. We chose solutions from just one topological sector to fix the initial con- ditions. The scalar field satisfies a Neumann boundary condition 𝜙x (0, t) = H. We study the scattering of a kink (antikink) with all possible regular and stable boundaries. For H = 0 the results are the same observed for scattering for the same model in the full line. For H ≠ 0, sensible modifications appear in the dynamics with several possibilities for the out-put depending on the initial velocity and the boundary. Our results are confronted with the topological structure and linear stability analysis of kink, antikink and boundary solutions. [ABSTRACT FROM AUTHOR]