Speaker
Description
We have extended the so-called QCD colour re-connection model with spatial constraints on the allowed re-connection between the colour strings in the Pythia8/Angantyr model. The Angantyr model uses the Pythia8 event generator machinery with sophisticated stacking of pp-like collisions to simulate heavy-ion events, without any assumption of a thermalized medium of QGP. So far, all sub-collisions are colour reconnected and hadronized independently in the heavy-ion collisions in the Angantyr model. In this work, we introduce a parameter that constrains the allowed colour re-connection between two colour strings based on the transverse spatial separation between the strings. This new parameter now allows us to combine all sub-collisions in a heavy-ion collision event at the parton level in Angantyr and perform re-connections between partons from different sub-collisions. We use the so-called QCD colour re-connection model of Pythia8, because its feature of junction formation enhances the baryon production with increasing multiplicity in collision events. We constrain the re-tuning of our model parameters to the pp collision level, and only parameters introduced in the Angantyr model are re-tuned at the pA collision level. We will show the effects of the spatial constraint in the colour re-connection model on the final state charged multiplicity, and production of identified hadron (and their ratios) in pp and pA collisions.
