Getting into the Swing of things in Heavy Ion Collisions

Jun 4, 2020, 12:50 PM

Oral Presentation Jets and High Momentum Hadrons Parallel


Leif Lönnblad (Lund University (SE))


In proton-proton collisions the underlying event is rather well
reproduced by general purpose event generators such as Herwig, Pythia
and Sherpa. The key to this success has been the modelling of
multi-parton interactions (MPI). Since long it has been recognised
that the (semi-) soft partonic sub-scatterings in such a scenario
cannot be treated completely independent and the concept of "colour
reconnections" was introduced, where the hadronising strings in an
event may be spanning partons from several different sub scatterings.

The Anganty model for generating fully hadronic exclusive final states
in heavy ion collisions in Pythia8 originally did not include any
collective effects. Rather it simply stacked a number nucleon-nucleon
collisions from Pythia on top of each other, without allowing any
crosstalk. Nevertheless Angantyr is able to reproduce fairly well
general features of events in pA and AA, such as multiplicity and
transverse momentum distributions of charged particles.

In this talk I will present the so-called Swing model for colour
reconnectsions, which originally was developed for the Ariadne/DIPSY
program. Contrary to the standard reconnection models (eg. the ones
implemented for pp in Pythia), the swing is applied already on the
perturbative level and will also affect jet evolution. This model is
now being implemented in the Pythia8/Angantyr program where it allows
for colour reconnections between partons from different
nucleon-nucleon sub-collisions in pA and AA. This requires a proper
treatment of the space-time structure of heavy ion collisions in
general, and in particular of the jet evolution in such events. I will
present preliminary preliminary results from this model with emphasis
on jet-related observables.

Track Jets and High Momentum Hadrons
Contribution type Contributed Talk

Primary author

Leif Lönnblad (Lund University (SE))


Christian Bierlich (Lund University (SE)) Smita Chakraborty (Lund University) Gosta Gustafson (Lund University)

Presentation materials