2026/07/08 by Yun Feng, Yunguo Jiang
#hep-th #nlin.PS
We study kink-antikink collisions in a (1+1)-dimensional ϕ8 scalar field theory with multiple degenerate vacua. We derive soliton solutions for different vacuum structures labeled by n=p2/p1, and focus on the cases n=2 and n=3. We perform numerical simulations in all topological sectors and for both kink-antikink (K K) and K K orderings. In the (-1/2,1/2) sector, the kink-antikink pair annihilates for all initial velocities. To the best of our knowledge, this full-velocity annihilation regime has not been reported in ϕ8 kink collisions. We also find fractal multi-bounce windows in the (-1,-1/2), (-1,-1/3), and (-1/3,1/3) sectors. Our main result indicates an effective-potential classification of these collision outcomes. We show that the shape of the effective potential is closely related to the final channel. It determines whether the pair escapes, forms a bion, annihilates, or changes sector. When the solitons pass through each other, the effective potential can change suddenly. This gives a possible mechanism for annihilation and sector change. Our results establish connections among topological structure, spectrum and effective potentials in higher-order scalar field theories.