A spacetime model for the perturbative swing

We present the development of a new colour reconnection model in Pythia where the full spacetime separation between partons constrains the reconnection probability throughout the final-state radiative shower. Building upon previous ideas of a perturbative dipole-based model, our objective is to introduce realistic spatially-based colour reconnections within the Angantyr model for heavy-ion collisions. Previous models were limited to the use of a rudimentary separation measure in the transverse plane to control reconnections. We investigate the impact of this novel scheme on final states in $$\text {e}^+\text {e}^-$$ e + e - , $$\text {pp}$$ pp , and pPb collisions as well as in PbPb collision systems and our main goal in this paper is to achieve a reasonable description of basic multiplicities in systems of varying sizes.