Extracting the top-quark mass and Yukawa coupling from the threshold scan at CLIC

摘要

The Compact Linear Collider (CLIC) is a concept for a next-generation accelerator at CERN, colliding electrons and positrons at energies up to several TeV. One of the main goals at the initial CLIC running stage is the measurement of the top-quark mass and width in a scan of the beam energy through the pair production threshold. However, the shape of the threshold cross section depends not only on the top-quark mass but also on other model parameters as the top-quark width, top Yukawa coupling and the strong coupling constant. We study the expected precision of the top-quark mass determination from the threshold scan. We use the most general fit approach with all relevant model parameters taken into account. In addition, we take the normalisation uncertainty into account as well as the expected constraints on the top Yukawa coupling and strong coupling constant from earlier experiments. We demonstrate that even in the most general approach the top-quark mass can be extracted with statistical precision of the order of 20 to 30 MeV. Additional improvement is expected if the running scenario is optimized. We also address the feasibility of the top Yukawa coupling determination from the threshold scan.