Jet flavors: From the standard candles to the top quark mass

The LHC began its second run in 2015 with upgraded hardware and software and an increased collision energy. With the higher energy scale the importance of jet physics has grown even larger than before. Jets are collimated sprays of hadrons that are produced in high-energy particle collisions. Understanding jets makes it possible to analyze the proton-proton collisions occurring at the LHC. This work studies jet flavors and their definitions in the context of the CMS experiment. The motivation for this is that the jet energy corrections applied to the CMS data depend on the jet flavors. A jet flavor is typically understood as the flavor of the quark or gluon from which the jet originated. In other contexts, e.g. b-tagging, the meaning of a jet flavor can be slightly different. Focus is given to the study of jet flavor definitions in simulations of proton proton collisions. Due to the structure of simulations the flavor definitions havean algorithmic form. The flavor studies begin by inspecting the robustness of a previously favored jet flavor definition between three different simulation software packages. Here the robustness of a flavor means that the physical properties of each flavor are the same in three different collision event types (standard candle events). Good robustness properties are observed between the software packages, but an excessive amount of jets is left without any flavor tag. A solution for this problem is sought for by developing enhanced flavor definitions. Two prominent new flavor definitions are found in the studies. The knowledge gained in the flavor studies is then applied to the studies of top quark production. The abundance of jets is particularly high in collisions thatproduce top quarks, so jet-related knowledge is important. It turns out that herethe jet flavor properties are somewhat similar to those observed in the standardcandle collision events. However, there are some differences that require further study. To conclude, a simulated measurement of the top quark mass is made.This provides valuable understanding of the practical issues related to a top mass measurement.