k-defects as compactons

TL;DR

This paper explores how nonstandard kinetic terms in k-field models can lead to the formation of topological compactons, including domain walls and sine-Gordon solutions, with potential implications for soliton theory.

Contribution

It demonstrates that k-fields with unusual kinetic terms can produce compactons, introduces examples like quartic $ ext{phi}^4$ and sine-Gordon models, and discusses properties of half-compactons.

Findings

Compactons arise in k-field models with nonstandard kinetic terms.

Quartic $ ext{phi}^4$ model admits topological compactons.

Existence of topological half-compactons is established.

Abstract

We argue that topological compactons (solitons with compact support) may be quite common objects if $k$-fields, i.e., fields with nonstandard kinetic term, are considered, by showing that even for models with well-behaved potentials the unusual kinetic part may lead to a power-like approach to the vacuum, which is a typical signal for the existence of compactons. The related approximate scaling symmetry as well as the existence of self-similar solutions are also discussed. As an example, we discuss domain walls in a potential Skyrme model with an additional quartic term, which is just the standard quadratic term to the power two. We show that in the critical case, when the quadratic term is neglected, we get the so-called quartic $\phi^4$ model, and the corresponding topological defect becomes a compacton. Similarly, the quartic sine-Gordon compacton is also derived. Finally, we establish the existence of topological half-compactons and study their properties.