We investigate kink-antikink scattering in the $\lambda {\varphi }^4$ model in the presence of an additional scalar field, $\psi$, that is in its quantum vacuum and interacts with $\varphi$ via a $\xi {\varphi }^2{\psi }^2$ term where $\xi$ is the coupling. The final state of such a scattering is either a bound state with eventual annihilation or a reflection of the kink-antikink pair. Without the $\psi$ field, the outcome is known to depend fractally on the initial velocity of the kink-antikink pair. In the quantum vacuum of the $\psi$ field, the fractal dependence gets modified and disappears above a critical interaction strength, $\xi \approx 0.1$.

• Received 13 March 2023
• Accepted 31 May 2023

DOI:https://doi.org/10.1103/PhysRevD.107.116017

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Published by the American Physical Society