Torbjörn Lundberg

Doctoral Student, Master of Science

Research areas and keywords

UKÄ subject classification

  • Subatomic Physics


  • Lund string model, Event Generator, Angantyr, heavy ion collisions, PYTHIA


I am working in the field of theoretical particle physics. My main topic of interest is thermal quantum field theory and its effect on observables. My master's thesis concerns temperature effects on particle decay rates of processes within a medium. My PhD studies aim to investigate and compare fundamental assumptions of different modeling schemes made in order to simulate heavy-ion collsions. A specific formalism with associated simulation program Angantyr, that relies on the Lund String model, makes up the foundations of my work.

I currently work with Professor Leif Lönnblad with the intent of contributing to the development of event generators for heavy-ion collisions that are based on the Lund String model (mainly PYTHIA8). My first project aims to implement a new type of interactions between pairs av Lund strings. In recent publications, it has been shown that string interactions before the onset of hadronisation qulitatively produces effects conventionally attributed to hydrodynamical flow and we are interested in pushing this 'microscopic' approach further. In parallell, I am involved with a reviewing project under the supervision of Associate Professor Roman Pasechnik where we investigate a naïve Z2-symmetry of the effective pure Yang-Mills Lagrangian and the effect of such symmetry on the value of the cosmological constant.

My master's project was performed under the supervision of Associate Professor Roman Pasechnik and we investigated generic decay rates of (pseudo)scalars and fermions in a thermal medium. Explicit one-loop calculations for Yukawa-type theories were carried out by hand within the framework of equilibrated real-time thermal field theory and fundamental differences for decay rates of (pseudo)scalars and fermions in the medium were identifield. The project resulted in the publication Finite temperature effects on decay rates in the real-time formalism by T. L. and Roman Pasechnik.

I mainly prefer working with well-founded equations when such luxary are available and I enjoy spending time on emerging myself in the line of thinking relevant to any topic. Hence, I often read a lot of material before I am comfortable with developing new thoughts.