Optimising top-quark threshold scan at CLIC using genetic algorithm

Abstract

One of the main goals of the future e+e− colliders is to measure the top-quark mass and width in a scan of the pair production threshold. Yet, the shape of the threshold cross section depends also on other model parameters as the top Yukawa coupling and the strong coupling constant. In this thesis, the study of the expected precision of the top-quark mass determination from the threshold scan at CLIC is presented. The most general fit approach is used with all relevant model parameters and expected constraints from ear- lier measurements taken into account. It is demonstrated that the top-quark mass can be extracted with statistical precision of the order of 30 to 40 MeV and additional improve- ment is possible if the running scenario is optimized. With the optimisation procedure based on the genetic algorithm the statistical uncertainty of the mass measurement can be reduced by about 25%