Kink-kink solutions in Bogomol'nyi-Prasad-Sommerfield impurity models.

Sławińska, K · Phys Rev E · 2025

basic_science · Level V

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Abstract

We show that BPS-impurity theories may support BPS kink-kink solutions, i.e., an energetically degenerated family of solutions describing two kinks at any mutual distance. This requires a singular impurity. As an example we consider the sine-Gordon and ϕ^{6} models coupled with such a BPS impurity. Interestingly, obtained solutions are identical to double sine-Gordon kinks and Christ-Lee kinks, respectively. We also study the spectral flow on the moduli space. All the modes have an odd number of nodes to cancel the singularity of the impurity.