“Study of jet substructure in heavy ion collisions: effect of combinatorial background on the subjet distance $\Delta R_g$”

In this project we chose and studied one observable in the context of jet physics, the subjet distance $\Delta R_g$. A toy model was used together with a Monte Carlo event generator (Pythia) to simulate the effects of the combinatorial background that is present in heavy ion collisions. The combinatorial background is subtracted with the constituent subtraction method. The effect of detector efficiency was studied as well. It was possible to recreate the shape of $\Delta R_g$ observed experimentally using the toy model. In addition, the jets $p_T$ and area distribution are presented in this report, as well as the dependence of $\Delta R_g$ on $p_T$. An interesting difference was found when comparing the event-by-event and the jet-by-jet subtraction methods of the constituent subtraction algorithm. This difference is not yet fully understood; there seems to be no simple explanation of the effect, so we suspect that it is a rather subtle implication of the algorithm that deserves further study.