Abstract
Recent measurements of collective effectlike signals in small collision systems has highlighted the need for new models to explain these phenomena. One good candidate for such a model is the AMY QCD effective kinetic theory, which is valid for systems in and outofequilibrium. This thesis is a collection of four papers which all investigate how to apply AMY kinetic theory to explain the evolution of small and large collision systems. In Paper I an analytical approach is used to extract collective flow coefficients from the kinetic theory. Paper IIIV then show the main work of the thesis, an implementation of the kinetic theory in the form of an event generator called ALPACA, as well as applications of this event generator to different systems.
Paper I presents results derived from the singlehit approximation of AMY kinetic theory looking specifically at the energy flow response to initial geometrical deformations in a purely gluonic system. It results in a scaling formula for the collective flow coefficients, and a proofofconcept study of the flow response for small collision systems, which gives results that are correct in order of magnitude.
Paper II presents the main work of the thesis, the Monte Carlo event generator ALPACA (AMY Lorentz invariant PArton CAscade). The details of how the event generator is implemented to faithfully reproduce the dynamics of AMY kinetic theory are discussed, and a validation of the framework in the case of an infinite thermal equilibrium is shown.
Paper III show how different systems thermalize and isotropize in ALPACA. Two different scenarios are analyzed; an overoccupied thermal system for thermalization, and isoptropization for anisoptropic Color Glass Condensatelike initial conditions. It is found that the system thermalizes correctly for the overoccupied case, compared to known analytical results.
Paper IV investigates collective flow in small systems using Color Glass Condensatelike initial conditions in ALPACA. Comparisons between the singlehit approach of Paper I and ALPACA are made, and the details of the difference between firsthit, singlehit and allhit are shown and discussed.
Paper I presents results derived from the singlehit approximation of AMY kinetic theory looking specifically at the energy flow response to initial geometrical deformations in a purely gluonic system. It results in a scaling formula for the collective flow coefficients, and a proofofconcept study of the flow response for small collision systems, which gives results that are correct in order of magnitude.
Paper II presents the main work of the thesis, the Monte Carlo event generator ALPACA (AMY Lorentz invariant PArton CAscade). The details of how the event generator is implemented to faithfully reproduce the dynamics of AMY kinetic theory are discussed, and a validation of the framework in the case of an infinite thermal equilibrium is shown.
Paper III show how different systems thermalize and isotropize in ALPACA. Two different scenarios are analyzed; an overoccupied thermal system for thermalization, and isoptropization for anisoptropic Color Glass Condensatelike initial conditions. It is found that the system thermalizes correctly for the overoccupied case, compared to known analytical results.
Paper IV investigates collective flow in small systems using Color Glass Condensatelike initial conditions in ALPACA. Comparisons between the singlehit approach of Paper I and ALPACA are made, and the details of the difference between firsthit, singlehit and allhit are shown and discussed.
Original language  English 

Qualification  Doctor 
Awarding Institution 

Supervisors/Advisors 

Award date  2023 Oct 27 
Publisher  
ISBN (Print)  9789180398176 
ISBN (electronic)  9789180398183 
Publication status  Published  2023 
Bibliographical note
Defence detailsDate: 20231027
Time: 10:00
Place: Lundmarksalen, Astronomihuset, Sölvegatan 27, Lund.
External reviewer(s)
Name: Schlichting, Sören
Title: Professor
Affiliation: Universität Bielefeld, Germany.

Subject classification (UKÄ)
 Subatomic Physics
Free keywords
 ALPACA
 QCD effective kinetic theory
 event generators
 heavyion physics
 Protonproton collisions
 small system collectivity
 phenomemology