Quantum mechanical string shoving

Sammanfattning

The Lund string model, which is implemented in PYTHIA, describes the hadronization process by representing the color electric field between a quark-antiquark pair as a massless, relativistic string. In the string shoving extension, the strings will have a Gaussian profile and will repel each other when they interact, acting like classical objects. When two strings interact and are positioned perpendicular to the reaction plane, they will produce a negative elliptic flow, meaning the movement will be along the minor axis of the elliptical interaction region. This thesis explores how the string shoving works in a quantum mechanical treatment. In a simplified quantum model, a collision between two strings is represented as a Gaussian wave packet interacting with a Gaussian potential. The Schrödinger equation is solved in both one and two dimensions to find that the strings move differently than predicted by the Lund string model. The simplified model shows that a large effective potential can suppress mobility of the string away from the interaction region. The radial probability current shows angular broadening, with peak structures appearing in certain parameter regions. However, the numerical robustness of these peaks should be studied further. The elliptic flow, calculated in a toy geometry, shows a decreases magnitude compared to the classical case. The work in this thesis motivates further studies of a quantum mechanical treatment of strings in hadronization.