Kink–antikink scattering-induced breathing bound states and oscillons in a parametrized ϕ4 model

Abstract

Recent studies have emphasized the important role that a shape deformability of scalar-field models pertaining to the same class with the standard [Formula: see text] field, can play in controlling the production of a specific type of breathing bound states so-called oscillons. In the context of cosmology, the built-in mechanism of oscillons suggests that they can affect the standard picture of scalar ultra-light dark matter. In this paper, kink scatterings are investigated in a parametrized model of bistable system admitting the classical [Formula: see text] field as an asymptotic limit, with focus on the formation of long-lived low-amplitude almost harmonic oscillations of the scalar field around a vacuum. The parametrized model is characterized by a double-well potential with a shape-deformation parameter that changes only the steepness of the potential walls, and hence the flatness of the hump of the potential barrier, leaving unaffected the two degenerate minima and the barrier height. It is found that the variation of the deformability parameter promotes several additional vibrational modes in the kink-phonon scattering potential, leading to suppression of the two-bounce windows in kink–antikink scatterings and the production of oscillons. Numerical results suggest that the anharmonicity of the potential barrier, characterized by a flat barrier hump, is the main determinant factor for the production of oscillons in double-well systems.

Emergence of oscillons in kink-impurity interactions

“…Such a natural way for oscillons to appear was recently discovered in the sinh-deformed (1 + 1)-dimensional ϕ 4 model [34], after the application of model deformations [35,36]. It also was found within the parametrized DW potential with a parameterized profile that for some values of the parameter reduces to the regular ϕ 4 potential [37]. Here, we show that oscillons also emerge naturally from collisions of kinks and antikinks in the classical (1 + 1)-dimensional ϕ 4 model without any deformations.…”

“…Usually they are explicitly introduced as an ansatz for the field configuration [32,33]. Besides, they have only been identified in the dynamics of a sinh-deformed (1 + 1)-dimensional ϕ 4 model [34], after applying a model deformation [35,36], and within a parametrized Dikandé-Kofané (DW) potential with a real parameter that controls its shape profile and for some values reduces it to the standard ϕ 4 potential [37].…”

Exotic Final States in the $φ^8$ Multi-Kink Collisions

“…Escaping oscillons, as well as bound states of oscillons, have been observed, e.g., in the sinh-deformed ϕ 4 and the double sine-Gordon models [24][25][26]. Formation of oscillons in kink-antikink collisions was also found in hyperbolic models [27] and in a parametrized ϕ 4 model [28]. In [29] a relation between the oscillational normal modes and the oscillon configurations was demonstrated.…”

Exotic final states in the $$\varphi ^8$$ multi-kink collisions

“…Escaping oscillons, as well as bound states of oscillons, have been observed, e.g., in the sinh-deformed ϕ 4 and the double sine-Gordon models [24][25][26][27]. Formation of oscillons in kink-antikink collisions was also found in hyperbolic models [28] and in a parametrized ϕ 4 model [29]. In [30] a relation between the oscillational normal modes and the oscillon configurations was demon-strated.…”